prototype mod bike being built...

[BikeTrialGuy]

how many of you would buy and ride a mod with the geometry of an echo team, but made out of Reynolds 853 steel, with vertical drops and an eccentric b/b.

i am in the process of making this bike so i can run disc brakes and not have to deal with the disc alignment/horiz. drops problem. let me know what you think!

-josh-

[TTownJon]

Sounds like a really cool bike.... But I just bought a new stock, so it will be a while.

Just out of curiosity though, why no have horizontal drops with the most inner position being the spot were the disks line up? Would allow people who want to run disks to do so easily and people who want the benefits of a horizontal dropout can still tention easily.

Also curios, how would an eccentric bb work on a trials bike?

[BrettM]

Sounds like a really cool bike.... But I just bought a new stock, so it will be a while.

Just out of curiosity though, why no have horizontal drops with the most inner position being the spot were the disks line up? Would allow people who want to run disks to do so easily and people who want the benefits of a horizontal dropout can still tention easily.

Also curios, how would an eccentric bb work on a trials bike?
It's nowhere near that simple. Got any idea how much that rear wheel will slide with adding or removing 2 links? Even a half link and chain wear will give problems. There are ways around it but they are complicated, time consuming, heavy usually, and adding more crap is shady.

[hydroboy]

What is wrong with running slots in the disk tab like this:




http://www.observedtrials.net/otn2/diskmountmodidea.GIF



Clearly its a shit diagram that took me 2 seconds, but hopfuly you get the idea.

[Simonk]

alex pv: the new sydney nolan

(famous australian painter sydney nolan:
http://www.scoop.co.nz/stories/images/0107/f30f46fe2695a1b7a05a.jpeg

wouldnt ned kelly shaped slots not be too great on a disk because there would be quite a lot of force there, causing it to move around?

[hydroboy]

Well i was thinking if you put it further towards the bb, the force the disk provides will be striaght down. Not sure if you get what i mean, but yeah.

[tomacropod]

Ned Kelly shaped slots would attract altogether too much police attention, although you would have a chance of being martyred outside a pub.

- Joel

[Ed Gildea]

bianchi had a good idea for single speed disc drop outs. go check it out.

[DangerousDave]

I haven't been able to find a pic of that bianchi single speed mount. I've only found pics of the full bike. Anyone have a more detailed pic?

[oicdn]

Well, freeriders seem to have no issues with this drop-out.....

http://www.abikeonline.com/images/hotshottoydropouts.jpg

That's the le toy and pornking dropout...... Why not make it like that and alleviate any shit having to do with oval disc slots and the such? Plenty beef....

[tomacropod]

I've often thought that the sliding dropout type designs from FR hardtails have lots of potential for trials bikes.

of course the above pictured dropout couldn't cope with trials disc forces...

- Joel

[oicdn]

You don't think so? 4 Bolts is alot of "locking" pressure.

[Darren]

I think the area around the top hole on the disc mount would be likely to snap right off. the bolt system would probably be fine

[MegamoMidwest]

what makes you think an eccentric hub would be any better at coping with discs than vertical dropouts. its essentially the same thing? the wheel has so much more leverage with a disc brake, that system would break really quickly.

[Elan]

eccentric bb sounds like an arse to be botherd wit m8. but go for et. interested to see how it becomes

[DanBowhers]

wait wait wait i got it, use a rim brake....

[BikeTrialGuy]

here is the deal:

-all tensioning of the chain will be done through the eccentric b/b, the only reason i would build this bike is so i can use disc brakes on a mod. i would design the frame to be ran with the standard gearing, whatever it is now. the option of running other gear configurations would be non-existent. ehh..whatever, im just going to build it. show you pics when im done.

[DangerousDave]

biketrialguy: Why wouldn't you jsut use regular horizontal dropouts on it?

[Tanner]

how many of you would buy and ride a mod with the geometry of an echo team, but made out of Reynolds 853 steel, with vertical drops and an eccentric b/b.

i am in the process of making this bike so i can run disc brakes and not have to deal with the disc alignment/horiz. drops problem. let me know what you think!

-josh-


I'd pay as much as it costs me to buy the steel and TIG weld it myself. But that's just me. I'm with DangerousDave on this one, whats wrong with regular horizontal dropouts that have been used for years? Maybe I'm just too strict to the "if it ain't broke, don't fix it" adage, but, I would like to hear why you think the horizontal dropouts wouldn't work fine.

[trialsbug]

Does your frame have 135mm spacing for the hub, or are you getting a 110mm eccentric hub made?

I have been working on this same problem, but I have gone in a different direction. I have an adapter from Therapy Components that has post mount holes. I am having a 110mm hub made that has a thread for a 12t cog on one side and a disc mount on the other side. The advantage of the Brake Therapy mount is that it is mounted on the axle, so the caliper always lines up with the disc.

[pav]

What is eccentric bb, i know bb but not eccentric, and i know i am retarted.

[tomacropod]

I think an eccentric BB on a mod would be fine because you have a frame mounted bashguard. On a stock I think the bashing forces would shift the BB around or destroy the eccentric sleeve. I've been thinking about this, an eccentric BB on a stock which actually has notches into which it can be seated and tightened would be a much better design. Of course I've never actually seen/used an eccentric BB in real life so perhaps I am misunderstanding the design. Does anyone know where I can get a schematic or cut-away look at an eccentric BB sleeve?

Echo made a disc hub in 110mm, and I think you can retrofit CK ISO shells onto their BMX hub a la the Dman (*grin* - I'll do it THIS way) and there's the megamo/gas gas hubs as well...or WERE...running discs and horizontal dropouts is just...too difficult...

- Joel

[BrettM]

If I was to ever design and build a mod with a rear disk I would use vertical dropouts like on mtbs and a derailleur hanger mounted chain tensioner. I don't care how often you might land on it, it is still ten time less hassle than any adaptor, eccentric bb, chain tensioners, or anything else would be.

I mean seriously. Steel bike, make a slightly thicker hanger for it. You will never break it. There are a few tensioners that are designed strong enough to be grinded on. You could even do your own. Mount it right onto the frame. Actually if you want I'll get a pic of how its done on my 1970 something Schwinn tandem. Its extremely simple and would probably be very effective in this situation.

[oicdn]

http://www.243racing.com/sites/racing234/uploads/product1big4.jpg
I know when I had my .243 Fox told me "those disc tabs are as beefy as they get, I'de like to see one get broken" when I was asking about trials usage....

http://www.243racing.com/sites/racing234/uploads/sl.frame.comp.site.jpg

Look at the disc tabs on his street frame...I'm betting same goes for those tabs as well. .243 doesn't have a shitty policy about warranty on everything except disc brake tabs....I remember him telling me about his riders, he has a 250lb tester that has a trials oriented style, and his rear tabs have never failed....

[tomacropod]

If I was to ever design and build a mod with a rear disk I would use vertical dropouts like on mtbs and a derailleur hanger mounted chain tensioner. I don't care how often you might land on it, it is still ten time less hassle than any adaptor, eccentric bb, chain tensioners, or anything else would be.

I mean seriously. Steel bike, make a slightly thicker hanger for it. You will never break it. There are a few tensioners that are designed strong enough to be grinded on. You could even do your own. Mount it right onto the frame. Actually if you want I'll get a pic of how its done on my 1970 something Schwinn tandem. Its extremely simple and would probably be very effective in this situation.
you're probably right. Simpler, lighter, stronger. That's whole point of SS to start with I guess...I've never ever had a problem with my Surly singleator, and if you use half links you can often get the chain tension "close enough" to use no tensioner anyway. Anyone got any info on retrofitting CK ISO shells onto BMX axles? Accessing the collar bolt on the HD axles seems to be a problem with ISO shells...the standard axle come in a 110mm width? If you're using vertical drops then a QR would be fine.

It's starting to sound easier to just use 135mm dropouts and have an array of hub choices. Plus if you have a mech hanger on there you would be able to have a geared mod...redundant perhaps...but a cool option...

- Joel

[MikeTheBike]

What is eccentric bb, i know bb but not eccentric, and i know i am retarted.
Eccentric refers to a situation wherein the bottom bracket's spindle is not in the exact center. As such, you can rotate the bottom bracket which increases and decreases the distance from the spindle to the rear hub, allowing the chain to be tensioned.

[Ed Gildea]

i found a picture just beef it up a bit and its good ;)

http://www.bikecult.com/works/archive/03bicycles/bianchicussEhu.JPG

[digby]

I dont know why your making this so much harder on your self than need be. Eccentric anything does not sound like a good idea for anything trials related. Go look at the megamo dual disc mod, nothing wrong with that design expect the chainstays are too long. I had one with avid discs and 18/12 gearing and it worked perfectly, no problems at all.

It seems like your building this bike around an encentric hub/bb. Why not get your normal parts together, stick horizontal dropouts on there, get the gearing/chain length figured out and build around that. If your going custom you may as well instead of dicking around with this encentric nonsense.

Yes it works fine for singlespeeders whatever, but they do not even come close to putting in the amount of short bursts of torque that trials riding puts on your equipment.

[Ebon Dragon]

No problems so far...brakes work fine throughout. Been like 5 months disc mounts are pretty beefy. But i guess it doesnt see too much abuse.

[/url]
http://www.observedtrials.net/album/data/500/358Dscn7483.jpghttp://www.observedtrials.net/album/data/500/358Dscn7480.jpg[url="http://www.observedtrials.net/album/data/500/358Dscn7483.jpg"] (http://www.observedtrials.net/album/data/500/358Dscn7480.jpg)

[trialsbug]

Echo made a disc hub in 110mm, and I think you can retrofit CK ISO shells onto their BMX hub a la the Dman (*grin* - I'll do it THIS way) and there's the megamo/gas gas hubs as well...or WERE...running discs and horizontal dropouts is just...too difficult...

- Joel
The CK option is expensive. I know about the Megamo and Echo hubs, but I can not find one anywhere.

A hub like the Echo rear hub (Quando), but with a disc mount is very simple. It will be interesting to see what it costs me to get one made. The first one is nearly done, but it is hard to say what the cost will be until the machinist has streamlined the machining process.

[tomacropod]

well If I were to run a mod I'd use a king rear hub, that's just me, I'd try the thread-on hubs first though. I'm sure that the echo and megamo hubs would uber expensive too...

doesn't monty have a mod with a rear disc now? Just using one of their hubs could work...

- Joel

[durkie]

The CK option is expensive. I know about the Megamo and Echo hubs, but I can not find one anywhere.

A hub like the Echo rear hub (Quando), but with a disc mount is very simple. It will be interesting to see what it costs me to get one made. The first one is nearly done, but it is hard to say what the cost will be until the machinist has streamlined the machining process.
does streamline the machining process mean producing several hundred of them? if so, you might want to look in to getting it from taiwan, because it probably does exist over there somewhere...(although i don't think i saw anything on the quando website - http://www.ktgroup.net, but the spacing wasn't clear)

[tomacropod]

trialsbug, if you're prepared to put some initial capital into it you could get 500 made at a low unit cost and sell them gradually. It would be in your interest to make a long, disc compatible mod frame available then :-)

I'm always keen to try new things, I think a 160mm avid disc on a mod would be interesting to try. Enter Naysayer.

- Joel

[s.s.king]

an 853 steel mod sounds great,I ride a brisa b20d. The only problem i have with the disk set up is finding a caliper to fit in the frame. I race a single speed moutianbike, the frame is custom made by True north cycles in Ontario Canada.I asked about a getting a trials frame made he told me about 2000.$ unless I found 5 or more people to by one.Hugh at true north uses eccentric b.b.s he charges more for singlespeeds made with rear entry fork ends.
good luck with your prototype,try to use 135 spacing hub you have lots of options.

[oicdn]

I'de try out the Mod if it were disc....I'm always down to try anything. I'm kinda wanting a mod too, just not quite to the point where I'm ready to drop the cash....."exploring options" LOL.

[BrettM]

A mod has a ton of potential for the rear disk to work for trials use. Way more than a stock. One of the ideas I've toyed with, but won't use would be to run a tiny tiny rotor. On a mod it would just need to be barely bigger than the bolt pattern for it. Then mount yourself some crazy 6 piston or whatever dh caliper. That would give you a ridiculous amount of power to stop that tiny wheel.

Personally I would never ever run a mod with horizontal dropouts. I would run a single speed tensioner just as you would on a mtb. I don't have a single problem hitting a much bigger derailleur or disk.

I'm too lazy to actually take a pic of how they do it on a 40 year old tandem, but basically there is a flat bar welded from the chainstays towards the ground with a slot in it. You than attach a derailleur pulley to that and slide it up and down to bring the chain up to the proper tension. So simple and useful its ridiculous.

[BikeTrialGuy]

alright, i'm a frame builder, i make custom beach cruiser/choppers from sccatch. i thought it would be cool to make a eccentric b/b mod bike. end of story. who cares how troublesome it would be, who cares if it would even work well. its all about trying new things. who knows what new things i will learn or techniques i will improve on by building this bike. everybody...take a chill pill. see, i have ridden and broken two echo em2's while running dual disc and i freakin loved it. i NEVER had an issue with stopping. best setup ever, i could ride in the pouring rain, in the mud wherever and not worry about it. the only problem was that the disc rotor didnt get full pad contact because of the chain tension. i fixed it by machining some gnarly chain tensioners that worked with those flimsy dropouts, then i had to run really wierd gearing. i thought enough, if moots can do it on their mt. bikes, than i can do it with a trials bike. besides, if it works, i will have a home made one of a kind trials bike. so blahhhh. peace.

[Trialsaddict]

alright, i'm a frame builder, i make custom beach cruiser/choppers from sccatch. i thought it would be cool to make a eccentric b/b mod bike. end of story. who cares how troublesome it would be, who cares if it would even work well. its all about trying new things. who knows what new things i will learn or techniques i will improve on by building this bike. everybody...take a chill pill. see, i have ridden and broken two echo em2's while running dual disc and i freakin loved it. i NEVER had an issue with stopping. best setup ever, i could ride in the pouring rain, in the mud wherever and not worry about it. the only problem was that the disc rotor didnt get full pad contact because of the chain tension. i fixed it by machining some gnarly chain tensioners that worked with those flimsy dropouts, then i had to run really wierd gearing. i thought enough, if moots can do it on their mt. bikes, than i can do it with a trials bike. besides, if it works, i will have a home made one of a kind trials bike. so blahhhh. peace.
Well said. Keep me posted.

[oicdn]

Nobody doesn't want to make stuff that might work, cause lots of people don't appreciate a broken face from failed stuff.....or it being in the stand more than it is between your legs....

[goose]

Found this picture, which I assume many have seen, WRT mod disc usage. Does anybody know if the therapy mout will stand up to rear disc usage better than say the usual disc mount??? Is it possible to use a Therapy mount on a stock. Their site says that only make adaptors for a few hubs.
Sorry if this is a tool-ish question.
http://www.teamplanetx.com/Team/team%202003/trials/Phil/pictures/my%20bike.jpg

[Cryo-Cube]

who in here is a math genius?

How much more power (%) would you get from running, lets say a 160 disc on a mod compared to a Stock ?

[trialsbug]

Found this picture, which I assume many have seen, WRT mod disc usage. Does anybody know if the therapy mout will stand up to rear disc usage better than say the usual disc mount??? Is it possible to use a Therapy mount on a stock. Their site says that only make adaptors for a few hubs.
Sorry if this is a tool-ish question.
I will let you know when the machinist gets my hub done. Brian @ Therapy components made a special bracket for me that uses a post mount instead of the IS mount. I plan on using a 6" Avid in the rear. I already have the bracket from Therapy components and it looks like it will work. I plan on posting pics once I get the hub and get everything installed.

[chronic]

I think you get something like 25% more power out of a 19" wheel opposed to a 26" as the wheel is smaller, and there is less leverage obviously.

[Bloodhound]

do rim brakes generally work better, worse, or the same on mods compared to stocks?

[felix]

do rim brakes generally work better, worse, or the same on mods compared to stocks?

worse

[Cryo-Cube]

do rim brakes generally work better, worse, or the same on mods compared to stocks?i say the same

imagine a 26" wheel where you try to spin the wheel but a friend is pushing to the other direction
now imagine a 20" wheel where you are trying to spin it and your friend is pushing here too.
you will need the same power to spin it because both of you are pushing on the same diameter.

its different on a disc brake because the disc has not the same size of the rim. the bigger the rim, the weaker your disc brake will be. The smaller the rim, the better it will work.

[goose]

Hi TrialsBug, I would ask you by PM, but I think some others may be interested. Why are you trying to use a brake therapy adaptor? Is it just because your bike doesn't have disc mounts, or is it because you figure the therapy mount will stand up to trials use better than a regular IS mount? Does anybody think a therapy mount would hold up to trials disc usage better? It's a good sign that several pro's were using them for their mods, I guess.

I would really like the option of using a therapy mount with my norco team trials, because it doesn't have a disk brake adaptor. This however, is not the case if I would have to use an XT hub, or buy a Hugi/Onx or whatever the few hubs they support. How thick is the brake therapy mount? Can you think of any way that a brake therapy mount could be added, say, to a Chris King ISO???

Just something I've been thinking about. I really love the modulation associated with discs, and now that I grind for grip, I can't wheelie nor manual as well (not that I could do it well before, but now it's pathetic). Thinking maybe a rear disc could fix my woes. I would LOVE to get a post mount frame like BrettM's, but that's kinda 'spensive.
peace,
goose

[Donkay]

http://www.gripsport.com.au/images/uploaded_images/47369993X-Lite%20disc%20mount9.jpg

I guess it works fine for Horizontal Drop outs, and yeah...I thought Monty did make new Mod Disc rear hubs too

[hophopsnap]

http://www.biketrials.com/comp/2004-01-18-Fontana/Stephen_Maeder/IMG_0915.JPG

:bigthumb:

[Elan]

~%30 more effectiveness on the mod versus the stock

[lowside]

i say the same

imagine a 26" wheel where you try to spin the wheel but a friend is pushing to the other direction
now imagine a 20" wheel where you are trying to spin it and your friend is pushing here too.
you will need the same power to spin it because both of you are pushing on the same diameter.

its different on a disc brake because the disc has not the same size of the rim. the bigger the rim, the weaker your disc brake will be. The smaller the rim, the better it will work.Wrong. The farther out you are braking, the easier it is to brake as you have better torque.

Think about why bigger disc rotors stop better.

[Elan]

jesus christ lowside, yo uarent even arguing about hte same subject. apples and oranges. no one is comparing rotor sizes, the whole topic is wheel size versus rotor size. if you have any brain cells in your canadian head, you will know that a 20" wheel with X mm roitor will be easier to decellerate than a 26" wheel with the same rotor.

[chronic]

Its ok, I am canadian!

I figured that one :naughty:, But lowside...forshame!

[trials king]

What kind of welder are you going to use?

[afrobot]

Jb weld will work as well as anything with a concentric BB. Some experimentation is good, the sexual kind for example. Your bike is going to fall apart ,or just plain suck.

Not to discourage you or anything.:dunno:

[goose]

Hey hophopsnap,

where did you get that picture, and do you know much about the setup? Please do tell!!!

[hophopsnap]

its from biketrials.com

Bike belongs to Zak Maeda

I have no idea on anything about that setup

[trials king]

If your going to weld the frame us a tig welder, no not mig a tig welder.

[hydroboy]

Magura would work about 1% better on a stock then a mod. Due to tyre hight to wheel size ratio.

[lowside]

Wrong. The farther out you are braking, the easier it is to brake as you have better torque.

Think about why bigger disc rotors stop better.jesus christ lowside, yo uarent even arguing about hte same subject. apples and oranges. no one is comparing rotor sizes, the whole topic is wheel size versus rotor size. if you have any brain cells in your canadian head, you will know that a 20" wheel with X mm roitor will be easier to decellerate than a 26" wheel with the same rotor.Are you fucking retarded? I'm not talking about rotor sizes, I'm using them as a comparison. The topic was whether an identical HS33 would have more stopping power on a 20" or 26" wheel. I said 26" as it has much more leverage to slow the wheel down.

Choke on a Canadian dick.

[Boo_Berry]

can u possibly post "work in progress" pics?

[felix]

Are you fucking retarded? I'm not talking about rotor sizes, I'm using them as a comparison. The topic was whether an identical HS33 would have more stopping power on a 20" or 26" wheel. I said 26" as it has much more leverage to slow the wheel down.

Choke on a Canadian dick.

I agree!

For those saying a rim brake has equal power on both bikes:
Imagine you do the same move on a mod and a stock.
Both times you weigh the same/have the same movement and the brake has to lock the wheel.
26" wheels have a 30% bigger diameter, thus the lever (distance between hub axle and brake) is longer, as well.
This lever is smaller on a mod, this is why the brakes are not as powerful as on a stock.

I always experience that when I switch from mod to stock.
For example a HS33 with Coust pads on a ground 26" Try All rim works amazing. On my mod I run the same setup, but the brake is only average.

[thetart20]

Both times you weigh the same/have the same movement and the brake has to lock the wheel.
26" wheels have a 30% bigger diameter, thus the lever (distance between hub axle and brake) is longer, as well.
This lever is smaller on a mod, this is why the brakes are not as powerful as on a stock.Thats correct - but the torque that the wheel applies to the brake is less on a mod too - since the wheel is smaller.

However, as Hydroboy said, a bigger percentage of overall wheel size on a mod is the tyre, so rim brakes dont work as well on a mod.

[Cryo-Cube]

felix you are forgetting that due to the smaller 20" diameter you are applying less torque on the same move!
As long as the brake is on the same diameter as the rim, the braking power should be the same. no matter if 26" 20" 90" or 5"

again, just imagine the brake is you trying to hold the rim with your hand, and the force(the trials move) is your other hand trying to spin the wheel.
no matter which diameter the wheel is. As long as your hands are on the same diameter, you will need the same force to spin/hold the wheel

http://mitglied.lycos.de/digitalglove/wheel.jpghttp://mitglied.lycos.de/digitalglove/wheels.jpg

if you spin a 26" wheel the torque is higher comapred to 20" but the brake is also farther away so it will be the same.
if you spin a 20" the torque is lower compared to 26" but the brake diameter is lower too so it will need the same power to stop the wheel

http://mitglied.lycos.de/digitalglove/wheel.jpg

[felix]

felix you are forgetting that due to the smaller 20" diameter you are applying less torque on the same move!
As long as the brake is on the same diameter as the rim, the braking power should be the same. no matter if 26" 20" 90" or 5"

again, just imagine the brake is you trying to hold the rim with your hand, and the force(the trials move) is your other hand trying to spin the wheel.
no matter which diameter the wheel is. As long as your hands are on the same diameter, you will need the same force to spin/hold the wheel

http://mitglied.lycos.de/digitalglove/wheel.jpghttp://mitglied.lycos.de/digitalglove/wheels.jpg

if you spin a 26" wheel the torque is higher comapred to 20" but the brake is also farther away so it will be the same.
if you spin a 20" the torque is lower compared to 26" but the brake diameter is lower too so it will need the same power to stop the wheel

http://mitglied.lycos.de/digitalglove/wheel.jpg

You win!
I always forget to consider this torque stuff!

[Elan]

i thought wewere talking about a 160mm rotor on either wheel, where did anyone say anything about hs-33s? i thought this whole topic was about disc brakes.

[Elan]

who in here is a math genius?

How much more power (%) would you get from running, lets say a 160 disc on a mod compared to a Stock ?
lowside- where the fuck did rim brakes come into the debate?

[Cryo-Cube]

when bloodhound asked the question DUDE
http://www.observedtrials.net/vb/showpost.php?p=126301&postcount=44

either way, now we got it covered

[BrettM]

Hi TrialsBug, I would ask you by PM, but I think some others may be interested. Why are you trying to use a brake therapy adaptor? Is it just because your bike doesn't have disc mounts, or is it because you figure the therapy mount will stand up to trials use better than a regular IS mount? Does anybody think a therapy mount would hold up to trials disc usage better? It's a good sign that several pro's were using them for their mods, I guess.

I would really like the option of using a therapy mount with my norco team trials, because it doesn't have a disk brake adaptor. This however, is not the case if I would have to use an XT hub, or buy a Hugi/Onx or whatever the few hubs they support. How thick is the brake therapy mount? Can you think of any way that a brake therapy mount could be added, say, to a Chris King ISO???

Just something I've been thinking about. I really love the modulation associated with discs, and now that I grind for grip, I can't wheelie nor manual as well (not that I could do it well before, but now it's pathetic). Thinking maybe a rear disc could fix my woes. I would LOVE to get a post mount frame like BrettM's, but that's kinda 'spensive.
peace,
goose
I had a brake therapy setup on a norco with a Chris King hub. They will make it for whatever setup you want. The guys at Therapy are really nice and really good at their work.

The downside is weight. Its gotta be 3 pounds just for the deal. Its really meant for if you have no brake mount when applying it to a hard tail. The system will be stronger than running it on a regular disk mount on a regular bike. If you got a trials specific mount probably not, I dunno. It is also quite expensive.

It is a replaceable system as well. If you break a piece on it you can buy the replacement, not the whole system. I have no idea how well it keeps the forces off your frame tho. A norco isn't meant to handle a disk force. If those forces make their way into that seatstay your frame is done.

[BrettM]

felix you are forgetting that due to the smaller 20" diameter you are applying less torque on the same move!
As long as the brake is on the same diameter as the rim, the braking power should be the same. no matter if 26" 20" 90" or 5"

again, just imagine the brake is you trying to hold the rim with your hand, and the force(the trials move) is your other hand trying to spin the wheel.
no matter which diameter the wheel is. As long as your hands are on the same diameter, you will need the same force to spin/hold the wheel

http://mitglied.lycos.de/digitalglove/wheel.jpghttp://mitglied.lycos.de/digitalglove/wheels.jpg

if you spin a 26" wheel the torque is higher comapred to 20" but the brake is also farther away so it will be the same.
if you spin a 20" the torque is lower compared to 26" but the brake diameter is lower too so it will need the same power to stop the wheel

http://mitglied.lycos.de/digitalglove/wheel.jpg

I disagree I think??? Why is it that a bigger rotor has more stopping power than a smaller one then??? I'm terrible with reasonings, but I know that is a fact. I can't think of differences when applying that thinking to the size of the wheel.

I think a bigger wheel with a rim brake will brake better than a smaller wheel with one like Felix originally said. It even feels that way to me as well.

[BrettM]

I know the dude and some others don't wanna hear this but here it is anyways. The simplest, lightest and strongest way to run a rear disk on a mod is to used vertical dropouts and a chain tensioner. 160 rotor or smaller even and you are laughing.

[felix]

I disagree I think??? Why is it that a bigger rotor has more stopping power than a smaller one then??? I'm terrible with reasonings, but I know that is a fact. I can't think of differences when applying that thinking to the size of the wheel.

I think a bigger wheel with a rim brake will brake better than a smaller wheel with one like Felix originally said. It even feels that way to me as well.

I'm totally confused now.
What Tarty and Cryo-Cube said sounds logical, but my experience tells me that rim brakes work much worse on a mod than on a stock.

[BrettM]

I'm totally confused now.
What Tarty and Cryo-Cube said sounds logical, but my experience tells me that rim brakes work much worse on a mod than on a stock.
I think they are half right. I think they messed it up right here.

"if you spin a 26" wheel the torque is higher comapred to 20" but the brake is also farther away so it will be the same."

I don't think they exactly cancel each other out if that makes any sense. Just because the torque is higher but the brake is farther away, doesn't just make it the same. I don't really know how you can just say its the same. I'm sure there is some sort of equation, and I'm pretty sure if you did it they wouldn't match up. I'm pretty sure the dude just said they were the same. If you believe they are the same then it makes sense. I don't think they would end up the same tho.

[Cryo-Cube]

I disagree I think??? Why is it that a bigger rotor has more stopping power than a smaller one then??? I'm terrible with reasonings, but I know that is a fact. I can't think of differences when applying that thinking to the size of the wheel.

I think a bigger wheel with a rim brake will brake better than a smaller wheel with one like Felix originally said. It even feels that way to me as well. argh
its tottaly different with disc brakes BECAUSE you are applying the force on a wider diameter (the rim) but braking with a much smaller diameter (the disc)

on rim brakes, you apply the force on nearly the same diameter you are also braking

here is a wrench analogy
http://mitglied.lycos.de/digitalglove/wheels2.gif


i have a little theory why mods "seem to" brake worse
i´ll write it later, it seem pretty logical to me.

[Cryo-Cube]

I think they are half right. I think they messed it up right here.

"if you spin a 26" wheel the torque is higher comapred to 20" but the brake is also farther away so it will be the same."

I don't think they exactly cancel each other out if that makes any sense. Just because the torque is higher but the brake is farther away, doesn't just make it the same. I don't really know how you can just say its the same. I'm sure there is some sort of equation, and I'm pretty sure if you did it they wouldn't match up. .
dude
you apply the force to the rim, and since THE RIM and THE BRAKE are nearly on the same diameter, the force you need to stop the brake has to be the same.

if you were right you could try to turn a wheel your STRONGER friend is holding but wouldnt succeed, but on a smaller wheel you would suddendly be succeed.
But thats wrong.
if a stronger friend is holding a wheel and you try to spin it and fail because he is stronger, you would still not suddendly be able to spin it when you both are using a smaller wheel

[BrettM]

argh
its tottaly different with disc brakes BECAUSE you are applying the force on a wider diameter (the rim) but braking with a much smaller diameter (the disc)

on rim brakes, you apply the force on nearly the same diameter you are also braking

The rim size is constant tho. Forget rim size it has nothing at all to do with the disk brake deal.

Why does a 200 mm rotor stop better than a 160 mm rotor on the same size rim??? I believe it is the same reason that makes a 26 inch wheel stop easier than a 20 inch wheel.

Just before attacking my whole theory could you answer this separately just so I can figure out if I agree at all where you are coming from.

Why does a 200 mm rotor stop better than a 160 mm rotor on the same size rim?

Thanks

[BrettM]

K I'm killing my mind here 2 hours after I woke up and I think I'm trying to start to understand what you are saying. I still believe that something is up as to why it feels like a stock brakes better than a mod. I'm interested in hearing that.

I think its got something to do with in a real trials situation on both bikes there is different amounts of torques applied to get the same distance lets say on both bikes, which would make it feel like one bike brakes better? Something along the lines of if its constant forces for both it would be equal performance, but there are different forces on each and thats what gives the different feel?

[Cryo-Cube]

the bigger the diameter where you are applying the force to stop the wheel, the higher the torque/force.

look at the first drawing http://mitglied.lycos.de/digitalglove/wheels2.gif
the bigger the little wrench gets, the higher the torque you apply-->the stronger your brake would be.

when you are rolling on the street you apply the force on the widest diameter-->the tire/rim.
when you have a

[Cryo-Cube]

K I'm killing my mind here 2 hours after I woke up and I think I'm trying to start to understand what you are saying. I still believe that something is up as to why it feels like a stock brakes better than a mod. I'm interested in hearing that.


like i said, i have a little theory why a mod rim brake feels less powerfull then on a stock
i´ll post it tomorrow along with pics so people get what i mean

[Ebon Dragon]

Does your theory have anything to do with how brakeslip is felt because of the length the pads would travel to the amount of degrees it travels?

[trialsbug]

Hi TrialsBug, I would ask you by PM, but I think some others may be interested. Why are you trying to use a brake therapy adaptor? Is it just because your bike doesn't have disc mounts, or is it because you figure the therapy mount will stand up to trials use better than a regular IS mount? Does anybody think a therapy mount would hold up to trials disc usage better? It's a good sign that several pro's were using them for their mods, I guess.

I would really like the option of using a therapy mount with my norco team trials, because it doesn't have a disk brake adaptor. This however, is not the case if I would have to use an XT hub, or buy a Hugi/Onx or whatever the few hubs they support. How thick is the brake therapy mount? Can you think of any way that a brake therapy mount could be added, say, to a Chris King ISO???

Just something I've been thinking about. I really love the modulation associated with discs, and now that I grind for grip, I can't wheelie nor manual as well (not that I could do it well before, but now it's pathetic). Thinking maybe a rear disc could fix my woes. I would LOVE to get a post mount frame like BrettM's, but that's kinda 'spensive.
peace,
goose
I am using the Therapy adapter for a few reasons.

First, my mod (Echo Team) does not have a disc mount.

Second, I agree with what Brett said. The easiest way to mount a disc on a mod would be with vertical mounts and a chain tensioner, but I don't have vertical mounts. The Therapy adapter gets around this by locating the caliper off of the axle. When the axle is moved to tension the chain, the caliper and disc will still be aligned.

Another reason to use this adapter is so that if I do have a failure I can just replace the adapter (unless my seat stay breaks.)

The parts are all at the machine shop. If I had them here I would post pictures. This bracket looks much nicer then the clunky looking adapter in the picture that was posted. That adapter looked like Zak's set-up, which was a prototype. This adapter looks much better because it was based on another design that Therapy is also working on.

Therapy can make these brackets to work with many different hubs, but there are some hubs that are easier to use then others. This bracket sits between the hub and the dropout, so the spacer on the axle has to be replaced with a spacer that allows the brake adapter to be properly held in place. He has already done an adapter for a King, but I am not sure if that was with MTB or BMX spacing. I believe that you need 14mm between the dropout and the hub bearing in order to fit the adapter, but I am not positibe about that number. I would have to look back at my notes.

I don't want to get into the mod brake vs stock brake argument, but if a mod rim brake worked as well as a stock rim brake I would not be going thru all this trouble to put a disc on the rear of my mod.

[goose]

Brett and TrialsBug,

Thanks very much for your input RE a brake therapy for my Norco/King setup.

Brett: For the Therapy/Norco/King setup you had, you though it was a bad idea because the canti mount would likely be broken? Would it help if a booster was added so both canti mounts were stressed (somewhat). Is there anythine else that would be an issue? Did yours break? If so, how long did it last? Which axle did you have at the time? How much did it cost? (sorry for so many questions, I'm just thrilled you've done it before).

Trialsbug: Please do post all your information when you get your parts back. I'm really into this idea of a rear disc via Therapy. Saves buying a new frame, and really allows you to use any frame and still get a really strong disc mount. My guess would be they did it for the solid axle version of the King. I wouldn't think that all those disc tourques on the King QR axle would be a good idea.

Thanks so much for sharing the info, sweeeeeeet.
goose

[BrettM]

Brett: For the Therapy/Norco/King setup you had, you though it was a bad idea because the canti mount would likely be broken? Would it help if a booster was added so both canti mounts were stressed (somewhat). Is there anythine else that would be an issue? Did yours break? If so, how long did it last? Which axle did you have at the time? How much did it cost? (sorry for so many questions, I'm just thrilled you've done it before).
I'm not really sure if it would be a bad idea or not. I have no idea where the stresses go. If any make it to the frame its a bad idea. A frame is designed and built to take the stress of what it was made for and what gets put on it. The Norco frame has no disk tab, therefor it isn't made for a disk. I considered the booster idea as well, I don't think it would work that great.

I actually only put it on and tried it out, thats as far as I got. Around that time was when I learned of Peyto. I tried it and it worked tho.

At the time I had a regular King qr axle. I'm not sure if the design has changed but basically they machine you a piece for your axle and then you swap them. I completely forget cost. 200ish maybe? It was a real long time ago.

If you wanted to email Therapy components go for it. When I did they were really fast and answered all my questions. You can also keep asking away here if you want.

[Tanner]

If your going to weld the frame us a tig welder, no not mig a tig welder.

Could gas weld it too. But, if you're using 4130 - TIG WELD IT ONLY. The haz using mig/smaw will be too much for 4130 to take and you'll crack it.

[afrobot]

I'm totally confused now.
What Tarty and Cryo-Cube said sounds logical, but my experience tells me that rim brakes work much worse on a mod than on a stock.
Mod brakes often suck because the rider is mechanically inept:bowrofl:

But seriosly folks.... Technically mod brakes should under identiacal grind/ pad/brake/adjustment work better as there is less leverage opposing the braking power. A larger rotor would in essense be the same as decrasing your wheel size.
Another reason mod brakes should potentially work better is there is less chainstay
resulting in less flex.

Can we go back to ragging on this guys mod now.:dunno:

[Cryo-Cube]

Technically mod brakes should under identiacal grind/ pad/brake/adjustment work better as there is less leverage opposing the braking power..:dunno: im gonna say it for the last time. They work the same!
Yes there is less levarge opposin the braking power but the brake itself has less leverage too, its mounted further in because of the smaller wheel

[WhiteRavenKS]

bwahahahahha. i just read this thread and laughed. print off a copy and go take it to a physics teacher and they will laugh too. at least someone got it right towards the end.

[afrobot]

I now concede. They are equal.



"""Can we go back to ragging on this guys mod now. :dunno:"""

[envcons]

Why does a 200 mm rotor stop better than a 160 mm rotor on the same size rim? Here we go Brett, I hope this makes sense.

There are two ways I'm going to try and explain this the easiest way is for you to think of the disk not as a solid disk but as many levers coming out of the axel. I'm sure you realize that a longer lever will give you more mechanical advatage because you are applying the force over more distance (ever cracked a vice? I'd bet you had a pipe over the handle when you did it). So the same reasoning can be used for the disk, bigger disk = more mechanical advatage.

If you didn't follow that let me try another way of explaining.

The only reason to use a larger disk is that it increases the amount of disk that moves through the caliper for each rotation of the wheel. The caliper slows your wheel by converting the rotational energy of the wheel into heat from the friction between the pads and the disk, this is why downhillers get discolored disks. However, a given caliper/pad combination can only convert so much rotational energy into heat, here's the important part.

The amount of heat that a caliper can create is proportional to how much disk moves through it in a given time.

So it follows logically that using a larger disk, therefore moving it more quickly through the caliper you can create more heat.

However, this only applys to wheels in motion. I may be able to use this line of thinking to explain why mod rim brakes feel less powerful than stock counterparts. Bear with me.

When a wheel is locked there is no conversion of rotational motion into heat, yet the wheel wants to stay locked, clearly this is due to friction between the pads and the rim. However, there are two kinds of friction, static friction and kinetic friction. Static friction is the friction between things that are stationary (think of it as resistance to motion). While kinetic friction is between things in motion (this friction is what was creating the heat in my disk explination) I'm bringing this up because of one interesting fact.

Static friction is ALWAYS stronger than kinetic friction, always.

This means that if you exert enough force to start something moving, then it will keep moving untill you take off quite a bit of the force, usually about 15%. Or, put another way, once you "break the lock" on your wheel you will have to put around 15% more force on your brakes to "relock" it.

This differance in static and kinetic frictions means that if you bridge the gap from static to kinetic your brakes will perform worse untill you get the wheel locked again. What this could be doing is amplifying the differance that Hydroboy mentioned between mod and stock wheels (the distance from the edge of the tire to the rim is a larger component of overall wheel size for a mod).

Just some thoughts, sorry for writing a book.

If anyone understood it all maby you could elaborate on the complicated parts that I sorta skimmed over.

[BrettM]

Here we go Brett, I hope this makes sense.

There are two ways I'm going to try and explain this the easiest way is for you to think of the disk not as a solid disk but as many levers coming out of the axel. I'm sure you realize that a longer lever will give you more mechanical advatage because you are applying the force over more distance (ever cracked a vice? I'd bet you had a pipe over the handle when you did it). So the same reasoning can be used for the disk, bigger disk = more mechanical advatage.

If you didn't follow that let me try another way of explaining.

The only reason to use a larger disk is that it increases the amount of disk that moves through the caliper for each rotation of the wheel. The caliper slows your wheel by converting the rotational energy of the wheel into heat from the friction between the pads and the disk, this is why downhillers get discolored disks. However, a given caliper/pad combination can only convert so much rotational energy into heat, here's the important part.

The amount of heat that a caliper can create is proportional to how much disk moves through it in a given time.

So it follows logically that using a larger disk, therefore moving it more quickly through the caliper you can create more heat.

However, this only applys to wheels in motion. I may be able to use this line of thinking to explain why mod rim brakes feel less powerful than stock counterparts. Bear with me.

When a wheel is locked there is no conversion of rotational motion into heat, yet the wheel wants to stay locked, clearly this is due to friction between the pads and the rim. However, there are two kinds of friction, static friction and kinetic friction. Static friction is the friction between things that are stationary (think of it as resistance to motion). While kinetic friction is between things in motion (this friction is what was creating the heat in my disk explination) I'm bringing this up because of one interesting fact.

Static friction is ALWAYS stronger than kinetic friction, always.

This means that if you exert enough force to start something moving, then it will keep moving untill you take off quite a bit of the force, usually about 15%. Or, put another way, once you "break the lock" on your wheel you will have to put around 15% more force on your brakes to "relock" it.

This differance in static and kinetic frictions means that if you bridge the gap from static to kinetic your brakes will perform worse untill you get the wheel locked again. What this could be doing is amplifying the differance that Hydroboy mentioned between mod and stock wheels (the distance from the edge of the tire to the rim is a larger component of overall wheel size for a mod).

Just some thoughts, sorry for writing a book.

If anyone understood it all maby you could elaborate on the complicated parts that I sorta skimmed over.
I thought I explained in a post above that I understood why a bigger rotor had more power and why rim brakes regardless of rim size had the same power?

[envcons]

Ok I didn't notice that, it might still help someone else. And it may help explain why mod brakes feel worse.

[goose]

Cool cool!

Brake Therapy emailed me back and said that they make kits for the Chris King ISO disc hubs, just as you said Brett. They also said that Zak Maeda has been using his Disk Therapy unit for 5-6 years with no problems. Hmmm, I'm thinking of taking the plunge... With this setup, I could have essentially the perfect bike, w/o having to spend 900 bucks and wait 5 months for a Peyto (even though I REALLY want one, can't really afford it).

Question: King HD axle, is it worth it? In all honesty, with the disc brake forces that will be put on the axle with a therapy adaptor, my inclination is to use the HD axle. I know the funbolts have been questionable, and the tightening of the cone with the odd allen key size has also been questionable. Any opinions out there?

thanx,
goose

[Ed Gildea]

why is this thred still alive. and what happend to the "prototype mod"..

[Ed Gildea]

just trying to stay on topic. but guess thats not what we do is it?

[Simonk]

This differance in static and kinetic frictions means that if you bridge the gap from static to kinetic your brakes will perform worse untill you get the wheel locked again. What this could be doing is amplifying the differance that Hydroboy mentioned between mod and stock wheels (the distance from the edge of the tire to the rim is a larger component of overall wheel size for a mod).


This makes absolutely no sense? Can you explain it better/logically?

[envcons]

No, because I'm pretty sure I'm wrong.

[Simonk]

fair enough :rofl:

[BrettM]

Cool cool!

Question: King HD axle, is it worth it? In all honesty, with the disc brake forces that will be put on the axle with a therapy adaptor, my inclination is to use the HD axle. I know the funbolts have been questionable, and the tightening of the cone with the odd allen key size has also been questionable. Any opinions out there?

thanx,
goose
Yes the HD axle is worth it I think. I don't know if it was coincidence or not but I broke my regular axles when I rode with a disk. Never without a disk tho. Probably coincidence. I've been riding a HD for well over a year, probably two now. Regular ones lasted 6 months.

I personally like the funbolts. They are a pain with rear derailleurs because they are a bit big. Thats why I have custom laser cut dropouts on the new bike tho with the derailleur pushed back a tad tho I guess. Not completely necessary. The allen key deal is a pain. I've had to do it just once. Build it up, break it in, when its loose soak the allen key and threads on the adjuster in blue loctite and re assemble. Worked for me. Also make sure you use the right allen key. Most people don't know that its not a mm size and end up wrecking it. 3/32" I believe.

[goose]

So Therapy says that they haven't made an adaptor for the HD axle, and it could be costly. They can readily make the QR. So, I'm not sure I really want to use the QR axle with the Therapy mount unless I can use the HD axle, it just seems smarter. The threaded axle can't possible resist as much radial loading, and the Therapy mount translates the rotational load of the disk and puts it on the axle and vbrake mount. So, I'm not sure if it's a good way to go, by putting extra load on a threaded axle. Any opinions? How frequent have people had problems with King Q/R adaptors and discs? I guess if you frequently check that the axle is tight, it shouldn't be 'too much' of a problem.

g

[rush]

No, because I'm pretty sure I'm wrong.
:bowdown:

Just about the only display of honesty ive ever seen on the intrawebs. Very nice.

[aj_the_first]

felix you are forgetting that due to the smaller 20" diameter you are applying less torque on the same move!
As long as the brake is on the same diameter as the rim, the braking power should be the same. no matter if 26" 20" 90" or 5"

again, just imagine the brake is you trying to hold the rim with your hand, and the force(the trials move) is your other hand trying to spin the wheel.
no matter which diameter the wheel is. As long as your hands are on the same diameter, you will need the same force to spin/hold the wheel

http://mitglied.lycos.de/digitalglove/wheel.jpghttp://mitglied.lycos.de/digitalglove/wheels.jpg

if you spin a 26" wheel the torque is higher comapred to 20" but the brake is also farther away so it will be the same.
if you spin a 20" the torque is lower compared to 26" but the brake diameter is lower too so it will need the same power to stop the wheel

http://mitglied.lycos.de/digitalglove/wheel.jpg


Actually Cryo-cube, for rim brakes, power is not the same on mod and stock. You were wanting to post a theory about why it "feels" like a mod bike has less power? Here it is in simple math:

Felix is right on the rim brake power being better on a stock bike because the thing you need to consider is that the brakes are applying pressure to the rim and the ground is applying the opposing force to the tire, SO, it is actually the difference in ratios between rim and outer tire diameter (not including tire compression).

Therefore:
A 26" wheel actually has a rim diameter of 22" and with a 2.5 tire it has an outer diameter of 27", thus the ratio in difference is only 1.227

A rear mod wheel has an actual rim diameter of 15" and with a 2.5 tire it has an outer diameter of 20", yeilding a difference ratio of 1.333

While they both have a constant 2.5" difference between the outer and rim diameter, they are different overall diameters, and therefore different ratios between the outer and rim diameters.

So, 1.227 divided by 1.333 = 0.92
Meaning that a mod bike has only 92% of the power on the rim brake as a stock bike.
Or, inversely: 1.333 divided by 1.227 = 1.086
Meaning that a stock bike has about 8 1/2% MORE power on the rim brake than a mod.

Nominal, but it's something.

It is the same as dropping down four teeth on both cogs. Even though the difference in teeth between the two cogs is the same, the gear ratio has changed.
Example: the "normal" stock bike ratios have changed from a 22t-19t to a 18t-15t. Both set ups are only three teeth different, but the 22-19 is a lower gear than the 18-15 ... I'll skip the math on this one.

On the disc brake with the same rotor diameter:
Since the outer diameter of a 26" wheel with a 2.5 tire is actually 27", the difference is 27 / 20 = 1.35, or 35% more power on a mod bike.
30% more power on a mod holds true when compared to a 2.0 tire (26" outside diameter) on the front of a stock bike.


Anyway, as a tip to the builder of this mod (I'm excited about this bike: I LOVE steel and I love all things dual disc):

I had a friend who went to the frame building class at the bike academy and since then has been building somewhat shitty frames on his Hank James Jig, but he was always a bit of an inovator when it came to doing stuff the simplest way he could think of.
He built a single speed frame with horizontal drops and disc brakes. What he did was build the entire frame on his stand with horizontal drops, assemble the drive train with a pre-stretched chain and the gear ratio he wanted while still in the jig, and then he used the disc on the hub and the caliper clamped to the disc (the brake lever was being pulled by a couple rubber bands) as his disc tab jig. He carved the tab a bit until it fit flush on the seat stay, and welded it on.
Presto! He had to use the same gear ratio and the same amount of chain, but as long as he did, the tab was always in the right place.

On a mod I assume you will know your gear ratio and how much chain you are going to use, so the wheel will be in the same spot, but rather than figure it out before hand and try to get the tab in the right spot, just do it the "Orange County Choppers way" and figure it out with the actual parts in place and no measuring.

[THEDEMOLITIONMAN]

Josh is a damn good welder and bike builder, he made my megamo expert mod into a disc mod.








Still holding up today after 3 years..

THEDMAN
PS- Josh this winter isn't that cold, so you won't have to go back early..lol

[Rudy]

Aj_the_first, thanks for being the first person to make any fucking sense out of this argument. I thought I was gonna have to draw a diagram.

[Ross]

Unfortunately, I do not think josh will be making this frame...he quit riding trials about 5 or 6 months ago. :( He was the only other rider in Norman, too.

[desvio2000]

I used to be the biggest disc brake fan in the universe but now i refuse to use them for several reasons (this is when i ran a rear bb7 for 2 years) on 3 disc frames. Megamo, revell, and monty

1) you drop the bike and it bumps the edge of the caliper bending tha adapter and you need a new one. This happens on a weekly basis

2) rotor bends and rubs beyound all belife and drives you insane after about 2 days

3) always fooks up and needs constant adjustment

4) weight

5) it randomly slips. Ive had some really bad injuries cause of that, but once in a blue moon it just slides a couple mm which moves the wheel like a foot.

6) Too much play. Eventually everything develops play and the wheel can move half an inch before the brake fully engages

[Mango]

desvio those are all mechanical problems on your side which you as a rider should have serviced. Rotors dont bend beyond all belief just from riding, they bend when you hit them on somthing. Discs arent that heavy, they are the same weight as a v brake with a booster.

[Nuckfut]

Here, I thought this thread was bout someone building a prototype mod.....

[desvio2000]

it is im trying to say rear disc mods arent that great. Verticle dropouts are nice though. Ive riddedn with both and I can say verticle are a lot less hassle.