Should I be worried about rear BB7 caliper breakage?

[goose]

Hi All,

I'll start off with a bit of backstory:

I tried using rear disc with a Therapy Adaptor on my Norco. Rear Avid BB7, 8". Loved the feel, therapy broke my Vbrake mount
http://www.observedtrials.net/vb/showthread.php?t=13288&highlight=king+therapy
and
http://www.observedtrials.net/vb/showthread.php?t=13807&highlight=king+therapy

Knight Cycles (yay) is making me a custom steel frame with a simtra-esque +40mm IS dropout with a nice brace bar. I was planning on using a rear BB7, 8". Just recently, though, I found that Mattyv8 and DEMOLITIONMAN have broken BB7s. Prior to this, I was unaware that the BB7's had any weaknesses other than cable friction! Should I be looking for another option, or is it likely that matty and demolition dude are just really strong/intense on their hardware. I'm a sport level rider, and haven't broken any parts since i switched to ISIS and bmx chains.

For alternatives, I like hope, but I don't want the trials brake, as I'd prefer not to have an ON/OFF switch. I would prefer Mono or M4 maybe? Do hope brakes suffer from bad pad play?

Thanks everybody!

goose

[Ali C]

for me, its a case of when they break, rather than if.

If it was any other brake, that would be enough to stop me using them, but seeing how bloody amazingly they work, I can cope.

[RomanC]

The BB7s are very cheap as well so that it will not be a financial strain. Also the rider's weight and types of moves are important parts of the equation.

[goose]

I take it you two both run Avids in the rear?

for me, its a case of when they break, rather than if.
If it was any other brake, that would be enough to stop me using them, but seeing how bloody amazingly they work, I can cope.

You're right, they are fantastic brakes. Perhaps I should just give it a try... Gound rims are sortof disposable, so now it's calipers that are disposable. I just hope they last more than a few rides. I suppose this experiment will be quick.

The BB7s are very cheap as well so that it will not be a financial strain. Also the rider's weight and types of moves are important parts of the equation.

I agree that they are among some of the cheaper brake calipers. But replacements cost 130, so that's not cheap if you break them twice a season. I agree that style/strength/weight are an important factor here! I'm 200lbs, but I don't ride 'that' hard.

I'm thinking that a first step is to use a more substantial adaptor. The one that come with avids are very thin, and I wonder if their whimpy looks have anything to do with the calipers breaking near the adaptor attachment.

[RomanC]

I've been on dual disc Simtra from June. I've had a 7'' with a modified adapter and now I am using an 8'' Avid polygon rotor. The power is just awesome and the fact that I don't have to dick around with it. The only trouble I face is that the disc adapter on my king universal gets loose occasionally. I am about 150 and ride it pretty hard.

[va_tick]

So...since were on the topic I'm trying to finish a build for a Sat ride. I have a new bb7 with 203mm rotor but I ordered it with the rear mount...no LBS carry the front 203 mount.....any suggestions besides ordering the correct mount which has been done, however, I didn't know if there was another compatible mount??

[goose]

I've been on dual disc Simtra from June. I've had a 7'' with a modified adapter and now I am using an 8'' Avid polygon rotor. The power is just awesome and the fact that I don't have to dick around with it. The only trouble I face is that the disc adapter on my king universal gets loose occasionally. I am about 150 and ride it pretty hard.

Thanks for that info.

About the disc adaptor. I know king doesn't recommend it, but are you using any thread locker on the disc adaptor splines, or on the bolts tha hold the adaptor in place??? I've been using teflon tape lately as a threadlocker. It's super cheap and not messy. Perhaps try that if you haven't already.

So...since were on the topic I'm trying to finish a build for a Sat ride. I have a new bb7 with 203mm rotor but I ordered it with the rear mount...no LBS carry the front 203 mount.....any suggestions besides ordering the correct mount which has been done, however, I didn't know if there was another compatible mount??

THREADJACKER! Hahahah, just kidding.

You might try using a rear hayes 8" rear adaptor. I've got a spare one here, and I just held up my avid against it, and I'm quite sure that an avid caliper would fit in it just fine. They use the same mounting spec, so I can't think of a reason why it wouldn't work. Lbs is much more likely to stock that one...

[va_tick]

So you held against an adapter for a 203mm avid? or 180-160?

[RomanC]

So you held against an adapter for a 203mm avid? or 180-160?
This will also be rotor dependant. I highly recomend going with the correct adapter as otherwise there might be small but annoying alignment issues.

[RomanC]

Thanks for that info.

About the disc adaptor. I know king doesn't recommend it, but are you using any thread locker on the disc adaptor splines, or on the bolts tha hold the adaptor in place??? I've been using teflon tape lately as a threadlocker. It's super cheap and not messy. Perhaps try that if you haven't already.

I just put grease on the little bolts that hold the adapter so that I could tighten them very tight. Although it is very easy to strip the heads and the it will be a PITA to get them out. Also king charges $1 per little bolt! I might try the teflon tape to see if it works, once I get the desire to mess with the bike.

[goose]

So you held against an adapter for a 203mm avid? or 180-160?

no no no. I have a hayes rear 8" IS adaptor. The only test I did was to see if there is sufficient clearance for the avid to fit. and there is plenty of clearance to fit the avid caliper into the hayes adaptor. I've done some mixing and matching before, and at the 185mm/160mm, hayes calipers don't fit in avid adaptors cause they're very chunky. At 203mm, there is no reason why rear hayes 8" adaptor shouldn't work with an avid caliper (use the CPS washers too). You only need this for tomorrow right? I've use and avid caliper on a 8" hayes IS mount once when I busted my hydro line.

picture of my ghetto measurement:
http://www.observedtrials.net/otn3/Hayes203Adaptor_AvidCaliperSMall.JPG

[va_tick]

Yeah just for tommarrow, I guess its a question of where the rotor sits in relation to the caliber not so much wether the caliber will mount with it?? Making any sense?? Sorry?

[va_tick]

doesnt matter.....the LBS dont carry that either.......wtf at our LBS....I've been mail-order parts since 88 (bmx days) because none of the shops around are worth a shit....I'm gonna go cry about it now and rub one off....:rant2: :wuteva: .

[goose]

Yeah just for tommarrow, I guess its a question of where the rotor sits in relation to the caliber not so much wether the caliber will mount with it?? Making any sense?? Sorry?

You make sense, but you don't gotta worry about it. Avid and Hayes use the same mounts and can share adaptors except for clearance issues, of which there are none for the 203mm rotor case.

doesnt matter.....the LBS dont carry that either.......wtf at our LBS....I've been mail-order parts since 88 (bmx days) because none of the shops around are worth a shit....I'm gonna go cry about it now and rub one off....:rant2: :wuteva: .

I suppose it's moot if they don't stock hayes adaptors. I've had to order lots of avid parts, but most bike stores around here have lots of hayes stuff. Too bad:(

Anyways, back to rear avid bb7 breakage. Any thoughts from all you rear avid users? Anyone else managed to break one? During what move???

[Acolyte]

Caliper will mount to Hayes, gauranteed, they're all 74mm(post mount Manitou). You'll just have to worry about the spacers in the Avid caliper, they may make the caliper to tall/short for the rotor, but not by much.

It WILL function, but alignment won't necessarily be perfect.


Edit: Hayes 8" adaptors are thicker than the 6" adaptors too, so that's another concern.

[goose]

spacers are not a problem, those seem to be required to meet post mount spec. Take a look at the picture with the avid attached to my old norco at the top of this thread. That's an 8" post mount therapy adaptor, designed and tested with both hayes and avid brakes. With the CPS washers, the avid lines up PERFECTLY with the 8" rotor. PERFECT I SAY! :)

So, anyone had problems breaking rear BB7s??? How? What conditions? During what move?

Do hope disc brakes have bad pad play??

[Giant1118]

I heard a bit about this. People saying the the calipewrs were weak or something. Ive had the same front avid for prolly a year and a half and I dont even have a bit of pad wobble.

But you're asking about rear bb7's so i dunno if thats getting a ton more force or not, I guess it is a little bit. But like I said, my front has lasted super long, still solid as ever, and i would say i prolly do more front wheel moves then most people.

[Giant1118]

btw, u getting v mounts put on anyways? just incase something happens...or is this disc only no matter what?

[goose]

btw, u getting v mounts put on anyways? just incase something happens...or is this disc only no matter what?

I haven't decided on the V-mounts. I'm tempted to to disc only all the way, as the disc mount will be uber strong. I've got spare disc brakes around, like an old hayes hmx-1, and 8" hayes mags. I prefer the look of disc only, and I want to use a mavic 729 rim, which is disc only (and baller). I suppose that it would be best to add vmounts "just in case", but that's not my inclination. I want to live on the edge a bit!

Still, lots of people use hope brakes, and marta's are popular now too. How do those feel in terms of pad play?

[Giant1118]

not too sure what u mean by pad play but i assume its the pad wobble thing people seem to always talk about. Ive never experienced it (pad wobble) So i couldnt even tell you what it feels like.

I know BrettM from bc is using martas (or was) on his red trials bike. Maybe wait fro him to post or pm him for some more specific details...thats prolly your best bet as hes been running rear disc for prolly 5 years now. So basically pm him either on here or on bt.ca or i think i have his email somewhere.

where u getting it made?

[goose]

not too sure what u mean by pad play but i assume its the pad wobble thing people seem to always talk about. Ive never experienced it (pad wobble) So i couldnt even tell you what it feels like.


play = wobble in this instance, you're right. Sorry, that's a good call. In the machine shop, we'd say that a bearing or bushing has developed 'play' or 'slop', meaning that it's not a tight fit and the parts are wobbling or moving around. I never knew what pad wobble felt like until I ran rear disc. It is there, but slight with avids. With hayes, it's bad. It just feels like little increments of brake slipping, because the pads can move a couple millimeters in the calipers, even while the wheel is locked. It makes small thunking noises, and is generally annoying.


I know BrettM from bc is using martas (or was) on his red trials bike. Maybe wait fro him to post or pm him for some more specific details...thats prolly your best bet as hes been running rear disc for prolly 5 years now. So basically pm him either on here or on bt.ca or i think i have his email somewhere.


I am eagerly awaiting for him to chime in, yup! I'll ask before too long.

where u getting it made?
Jerry Knight aka Knight Cycles is in Seattle. I put the down payment on it at xmas when I was home in vancouver. He does fillet brazing, just like peyto.

[guumer]

what will the geo be?

[goose]

what will the geo be?

It's a scaled up zebdi for a tall guy. Longer seat tube and wheelbase. All other geo should be the same. 15.5" seat tube, 1050mm wheelbase, 71deg head angle, 15.5" stays, +10mm BB, +40mm IS mounts with megamo/simtra-like bracing. All measurements with a 3" susp fork. Should be off the hook, I can't wait:)

I'm just a little worried, about the rear BB7. As you and Dan know, I'm starting to ride a little harder now, and when a rear brake slips, it can lead to bad bails. I bet if it breaks, it'd lead to a bad bail too:(

[carnagr]

Zebdi had 15.75" stays if I remember correctly.

[goose]

Zebdi had 15.75" stays if I remember correctly.

not mine, they measures around 15+7/16". MK5 has 15.5" stays fo shizzle

[carnagr]

Well I had an MK5 and it definitely had 400mm stays, which is 15.75".

[goose]

Well I had an MK5 and it definitely had 400mm stays, which is 15.75".

OK man, I didn't mean to insult. I'm dead serious, though. BB axis to rear axis is a hair under 15.5" on mine. I just measured it again. That's some bad tolerancing on a production frame, if the chainstays vary by 0.25". Anyways, i fail to see how this has anything to do with either rear BB7 failure, or hope pad wobble, which is all I'm looking for in this thread:)

[goose]

so no word on Hope's Pad wobble?? I'm sure SOMEBODY must know:)

[THEDEMOLITIONMAN]

I use to run avids on my megamo dual and I broke two of them in less 3 months. I love the stopping power of an avid brake, they just need to beef them up a bit.







G-luck,

THEDMAN

[guumer]

what part broke do you have any pics?

[toyota200x]

If you are a lighter weight person(150 or so) I would think you would have that many problems with breaking the BB7.

[goose]

I use to run avids on my megamo dual and I broke two of them in less 3 months. I love the stopping power of an avid brake, they just need to beef them up a bit.

G-luck,

THEDMAN

I'm going to go on the assumption that you're a higher level rider that does more big moves than I. I'm sortof an old schooler. I love skinnies, max 6 foot gaps (if I'm lucky), 1-2 foot side ups, pedalups, and I'm starting to do spin moves more now.
I am considering making my own avid brake caliper. Using their internals and lever arm, I'm sure that one could make a stronger caliper block without too much trouble. Theirs is cast with some form of white aluminum, so it's not that strong, and the part that connects the round piston part to the 74mm mount could easily have more material for. It's an aggressive project, though.

If you are a lighter weight person(150 or so) I would think you would have that many problems with breaking the BB7.

6'4", 200lbs. So I wouldn't say i'm lighter weight. I ride sport, pretty smooth, not big moves. I'm might try the BB7 for a while, and if it brakes, start replacing it with something else. I have two spare hayes mags, and an I'd consider trying a hayes mech, hope, or magura. I don't want this to be pure on/off feel. I quite like the progressive feel of discs.

what part broke do you have any pics?

I've found this picture from an older mattyv8 thread, showing the locations of the breakage on a simtra st-1. The red arrows denote the locations of failure. Twice on the caliper, and once on the adaptor. I'm also wondering if making a stiffer adaptor could help. The avid adaptors appear to be cast, and pretty thin. A stiffer adaptor could help reduce these BB7 failures. BrettM's discs never failed, and the only difference there is a steel postmount, rather than a cast aluminum one. I'm sure his mount has less flex!

http://www.mattvenhuizen.com/avid_caliper.jpg