Cyclocross - Cantilever Problem - Does this bike shop really know what they are doing?
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04-14-10, 10:42 PM
I took my bike into a shop down here in southern California for a complete tuneup - 150 bucks. They supposedly clean and check everything, re grease etc, true the wheels, their best package. I paid 20 bucks extra for new shifter cables and housings.
First off I notice the tire pressure is way too high, but that's nothing too bad. Secondly I notice that it is auto shifting when in the small cog....could be cable stretch.
As I'm walking out the guy tells me "O, and the brakes shudder, nothing you can do about that!"
So I check the brakes when I get back and they squeal and shudder like crazy, both front and back, both cantilevers. The brake pads were actually toed the OPPOSITE way (so that the end of the pad contacts first). Finally the cable coming down to the yoke had been significantly shortened, and cut so it cannot be lengthened anymore. I think this may be the problem for the fronts. For the rears however, they wrapped a small piece of wire tightly around the transverse cable to stop the yoke from moving farther down:
Is this even safe?! I almost crashed riding it home because of the front brakes not working, but now I'm worried if I should even trust these guys to work on my bike again (they supposedly guarantee their work). Do they just not know how to adjust cantilevers or am I missing something?
Front Brake Setup (is the yoke too high?):
Also, are the larger spherical washers supposed to be on the outside or inside of the cantilever arm? I previously had them inside (next to the brake shoe) but they have it setup the opposite....
04-14-10, 11:47 PM
Kudos to you for going to a local shop. But when you aren't happy, well you should go back with it. If they can't or won't fix it after all you've spent, never go there again.
First off it looks like you have two different types of brakes front and rear. Tektro on the front and Avid on the rear. Nothing wrong there. However, the front type straddle cable is different for each. The one on the front is dangerous type, whereas the Avid labeled one in the rear is the safety type. If I were you I would switch the staddle cable rear to front. If the cable slips on the front the way it is set up, the cantilever springs will make the straddle cable stretch across the tire, lock up the front wheel as it catches the tread and cause an endo. It should be possible to swap the straddle cable.
To fix that you would need some tools. It looks like they did cut the brake cable short on the front, so readjustments are limited though. The Avid branded safety straddle system uses the brake cable, the same cable that pulls from the bar lever, as one half of the straddle. The idea is that is the cable pulls though or breaks in two, the cable will not rest on top of the tire.
If that happens on the rear tire, you will not endo. It will just slow you down, or stop you. On the front, this is a problem. This is only one reason why linear V-brakes are better, imho.
As for what that rivet looking thing is on the cable in the red star photo, I have no idea. My geuss is that it is supposed be inside, or behind (as the case would be from the phot point of view), the round cable holder (the round thing marked Avid). It may be possible to slip it up the cable and around the flange so it can set in there. Maybe it functions to guide the cable and reduce friction. I've never seen this thing before.
If the front brake is not working, is it becasue the pads do not contact the rim? It looks like the cable may have slipped as there is a kink in it above the clamp. Since we cannot see the rim-brake pad area, we cannot see the alignment and clearance. It looks like they might be working. If the brakes are juddering badly, it could be many things. If there were certain spacers missing from the mounts or if the brake mounting bolts were not snug then the cantilevers might wobble and judder. The spacers look right to me. They come with the brake when new in box just so that you have them. They are meant to be shuffled around so you can get the better fit of all proper combinations. Distance to the rim from the brake studs vary from bike to bike and fork to fork. The front brake "yoke", what i call the straddle cable, is not looking too high. Consider that many people put fenders between the tire and the cable, and that is a benefit of cantilevers.
On the rear brakes you mention a small piece of wire to keep things from sliding. I presume you mean a section of cable housing? That's part of the saftey feature.
Well, I can't help more. I sort of hate cantilever brakes. They can work. I have them as rear brakes only on my commuter, and a tandem (with a drum brake), and on my wife's cross bike. The front brakes are all V-brakes on thos three bikes. The front brake is the most important one. If you put a V-brake on the front you will probably need a travel-agent to make it work on the Redline's presumably Tektro road levers.
Welcome to the hassles of cantilever brakes! You will learn a lot of good stuff.
04-15-10, 02:12 AM
Dunno what that 'star' thingy is, but it's a std. way of setting up canties.
The brake-wire goes through the coin shaped thingy, through the tube (to get a fixed length) and bolts to the cantie.
The other wire 90 degrees on is fixed on the coin shaped thingy and goes on the other brake.
You have different lengths for different spaced canties (type 'c' type 'd' etc.)
As for the spherical washer being on inside or outside?... Inside might increase stopping power, but might also increase chatter.
I'd RTFM before flaming too many ;)
Auto shifting in the small cog? Tune up fail. It's not hard to "pre-stretch" the cables to get most of the new cable stretch out of them before they leave the shop, and totally prudent if one wants their adjustments to last more than a ride. Even so, I would look to the high-speed limit screw as the culprit here, or far too much cable tension. I do my major derallieur adjustments in this order: Limit screws, attach cable, cable tension, whole bunch of shifting with pushing hard against the low-speed limit (shifting hard into the easiest gear), release cable, pull slack through, re-attach cable, cable tension again, then B-tension screw.
Backwards toe-in? Tune up fail. Anyone paid to wrench on bikes should know how to do this. 1-2mm gap at the back of the pad is often good. I put a thick piece of paper between the back of the brake pad and rim, squeeze lightly, then tighten it all up. With V-brakes and V-brake pads I always try no toe-in first just to see if I can get away with it. I hear the fork mounted brake hangers can help with properly set-up front brakes that still chatter.
Uneven brake pad set-up on the front brake? Tune up fail. I would also set up the pads so that the thicker pair of washers in inside the brake arm. This will spread out the brakes and give more power (but mushier feel).
Sheldon has a good article on setting up brakes, it's a good read for de-mystifiying brake issues. http://sheldonbrown.com/canti-trad.html
As far as the hangers go, I've never had problems with the type you have on the front, and actually prefer them as they let me change the straddle cable height for tuning the brake feel and performance. The type you have on the rear is "foolproof". Take that for what it is!
04-15-10, 11:52 AM
Yea ive done extensive research with cantilevers in the past (setting them up myselves) and these guys basically have them setup the OPPOSITE of what I usually did. I got the front straddle cable instead of the link wire specifically for the purpose of adjustment, if I endo then its my fault for not setting up the cables right. The rear piece of metal really looks unsafe, maybe the picture doesnt show it, but its literally just a piece of wire they bent around the cable (it was NOT on my bike when I took it in, and looks quite ghetto).
As for the front, the yoke is definitely too high ( I used to have it set much lower for more power) and while there is sufficient pad clearance the pads immediatly contact the rim and then have no real power to them. I tried toeing in the brakes the correct way and it has seemed to help a little, but the front brakes were tightened so hard the spherical washers were actually now deformed and I cant get them off the post (they get stuck on the threads)!
Pretty shoddy workmanship if you ask me.....especialy for 170 bucks. Im going to take the bike back in soon, but I am quite worried that these guys really dont know what they are doing. Might have to have a talk with the manager.
Yep, proper set-up is what you're paying for. I'd talk to the manager, at the very least so they know what's up. I'd be pretty wary about having them work on my bike again, that's for sure.
04-16-10, 03:46 PM
Yea, brakes are quite important to me.....and now they dont work at all! I guess even bike shops have trouble with cantilevers, yeeesh.
04-22-10, 02:04 PM
I would ask for my money back.
04-22-10, 03:47 PM
They did clean and lube the whole bike (supposedly) and do everything else, so I can hardly see how I can ask for my money back. The only thing that was really screwed up was the brakes ( I was having some gear shifting problems before I took the bike in). Im definintely going to be bringing the bike back in and see what they produce, if it is still sub-par after a second inspection then we will really know!
04-23-10, 04:05 PM
They owe you a longer front brake cable so you have the option of lowering the yoke.
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