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Mod bike- rim or disc in rear?

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Discussion Starter · #1 · (Edited)
Hi all-
I’m returning to bike trials after about a 20 year hiatus with life. I used to ride pro- mod and stock- when we all used rim brakes (Magura HS33) on 4-post mounts. Some guys started riding discs, but they were known to be unreliable, and not lock up consistently enough for true pure trials riding. So you’d see them on 26” fronts mostly in the early 2000’s.

Now the only options I see for mods are disc in the rear- so I bought an Echo Ti with disc rear (and due to shipping error, rim brake front).

The big question: HOW THE HELL do you all ride Mod with a Disc?? I’ve fallen on my ass more than I ever thought possible because they simply don’t lock like a rim grind and rim brakes. I modulate my ass to the ground far too routinely.

Yes - sure I’m old. But I can still wheel hop and table gap my dirt jumper- so I’m kinda thinking this is a disc brake issue?? I ditched the cheesy Echo Czar single piston for Magura MT7 quad piston disc with 160 Magura rotor (the heavier one) and the DH (grabbiest) gold pads.

Is it that I haven’t properly broken them in? What all do you guys do? I poured water on them and dragged the brake, repeatedly, and can still pedal through it after several days/sessions of braking in.

I see videos with pros now and they’re all running mod disc rear, and I don’t even feel confident enough to rear wheel off a picnic table let alone hit the local sections.

thanks in advance —
Andrew
 

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tda
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Is this THE andrew Fulton!!!?

I’m not sure on the disc thing, charlie rolls shreds insane... you shouldnt be slipping thats for sure !!!! Super silent bite and modulation? not much modulation with trials pads in there.

hs33 takes time to grind, some still prefer it... I run hs33 rear and disc front, but honestly wouldnt mind f/r disc
 

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tda
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For some reason I prefer disc on mods and rim brakes on stocks
Sounds like you got something amiss
Rub some tar on those rotors
ahhh homie probably doesnt even have a grind on them rotors!! Just a light one, not as brutal as rim grinding... thats the pro secret, tar can get bad in d rain.
 

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Discussion Starter · #8 · (Edited)
ahhh homie probably doesnt even have a grind on them rotors!! Just a light one, not as brutal as rim grinding... thats the pro secret, tar can get bad in d rain.
Y’all wildin’… haha. I can appreciate some poor bastard actually tarring or grinding a disc. Haha.
man— the good ol’ days when I used to carry a small lump of tar in my pocket for that added grip on a street section. All wrapped in a torn-off piece of plastic bag- looking far more nefarious than it ought to.
 

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Discussion Starter · #10 ·
not sorted as of yet. Busted my ankle pretty badly with the disc not locking up and tried to catch myself when falling back quickly.
As of now- definitely don’t trust disc nearly as much as I would/did rim brake.
Im certain it’s a “me” issue— but frustrating none the less as the discs still don’t lock— more come to a mid/slow stop.
 

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tda
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not sorted as of yet. Busted my ankle pretty badly with the disc not locking up and tried to catch myself when falling back quickly.
As of now- definitely don’t trust disc nearly as much as I would/did rim brake.
Im certain it’s a “me” issue— but frustrating none the less as the discs still don’t lock— more come to a mid/slow stop.

what kind of disc/lever/rotor situation??

im a big fan of trialtech disc pads, most pads available don’t give the bite we enjoy
 

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There was some packing tape stuck to one of the rotors. When i peeled it off it left glue. Rubbed that off with a clean handkerchief soaked in isopropyl, did the same to the other rotor too cause i had accidentally touched it with a slightly greasy finger. Then i followed tarty instructions for bedding in and after 10min the braking surfaces were shiny and the rear was holding on backhops, front holding on endos. Havent gone full trialsin yet but seems like everything will hold great. Hope brakes and rotors.
 

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not sorted as of yet. Busted my ankle pretty badly with the disc not locking up and tried to catch myself when falling back quickly.
As of now- definitely don’t trust disc nearly as much as I would/did rim brake.
Im certain it’s a “me” issue— but frustrating none the less as the discs still don’t lock— more come to a mid/slow stop.
Sucks about the ankle! Hopefully it's just a light tweak rather than anything too serious.
When I first went to disc on a mod from rim brake it did take a bit of time for me to get confidence in it. When you're expecting a rowdy, bitey brake it's weird to go to a silent one that doesn't feel quite as aggressive, but once they're set up they shouldn't feel too dissimilar.

Which brakes are you using on there? If they're the Echo ones, they aren't really all that great. Echo chose to use a super hard steel for their rotors - they're noticeable harder than Hope ones, and take forever to bed in. In my experience they don't really give the same kind of performance ultimately either.

Until they're fully bedded in, disc brakes will suck too. You need to shoot for there being a mirror-like finish on the braking surface. That's when they're really bedded in, and you should be getting most performance.

Are you getting any honking from the brakes either dry or wet? If you do, quite often that can mean that they're contaminated which would explain the lack of performance. They can be pretty sensitive to contaminants (even touching your rotors with your skin can be enough to do it with some setups), so if they've happened to have any contact with anything either during production, assembly or riding that could be a factor.

Other than that, changing to some better rotors and upgrading the pads would be a good way to go. If you want to split the cost you can do just one of those things, but it's worth bearing in mind if you suspect that there's a chance the existing setup is contaminated then you will then be contaminating your new rotor/pads if you fit them with the existing pads/rotor.

In terms of why mods switched to discs, there are way better options out there than there used to be. Hope Tech 3 Trial Zone (now Tech 4 Trial Zone) brakes are miles ahead of what used to be on the market, as are things like either the two-piston or four-piston Magura brakes. There are better rotors out there now too, along with more trials-specific disc pads that give way better bite than normal MTB orientated pads. With discs you get a lot more consistent power, less maintenance (no need to grind rims regularly and dick about with pads), much better modulation than a rim brake and amazing hold. As before, a well set up disc brake should feel very grabby too. For comp dudes there should be less of a drop in performance in wet or muddy conditions too.

They haven't really taken off on 26" comp bikes in the same way for a few reasons - spoke flex, the extra weight of needing to run large rotors to get enough power, and most likely the extra weight needed for a disc mount and suitable reinforcement on a 26" frame. It's a little different on a street trials setup as the pros outweigh the cons, so that's why you'll see them on things like the Inspired Hex.

EDIT: One thing I forgot to mention before, disc brakes are really, really sensitive to caliper alignment and piston centralising. It makes a huge difference. I thought my brake needed a bleed and there was something seriously wrong with it to it working perfectly just by centralising the pistons. This video explains it pretty well -
It's worth taking the time to make sure that the caliper is set up perfectly square, and that your pistons are contacting evenly and at the same time.
 

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Discussion Starter · #16 ·
I appreciate the advice everyone! So I busted the ankle badly enough to warrant staying off it for a few weeks- and kept me shy on riding for a few months. In that time- I built up my old rim brake pro mod, and it’s was instantly like being at home. Made a few picnic tables for practicing ups and gaps in the yard… which were put to use with the old bike.

Still struggling with the disc setup on the new Echo. Definitely did the tons of fresh water and dragging the brake cycling. No significant honking, so I’m skeptical the pads are contaminated, as I’ve replaced once already.

BRAKES: Magura quad piston MT-7 front and rear
ROTOR: with a Magura storm HC 160mm.
PADS: Magura 8.R (downhill race compound said to be their grabbiest)

anyway- thanks for the advice. I’ll keep messing with it… but in my “old man shakes fist at cloud” way- I still wish Mods came with rim brakes! Haha… thanks everyone!
 

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tda
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man I dunno about magura hydros… and maybe 160 is ok on a mod i wouldnt use anything but 203 on stock, and trialtech/jitsie pads… usually stock pads, even made for race, are shit beyond for trials. We need instant bite, stock pads are made to give “bite” but last long on downhills.
 

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As said above it would try out some Trialtech or Jitsie pads with them and get it set up as close to perfectly as possible. I know a few people running Magura MT5/7s and have no issues at all, quite the opposite in fact!

Disc is perfect for a mod bike, modulation and oodles of power/hold (and i love the silence!), on the front a HS33 might have the edge; i've just switched from running dual Maguras for 6 years to dual Hope Tech 4 Trials and don't see me changing back :D
 
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