Gillparis

Hi all

Apologies for the long post. I have an old road bike that has cantilever brakes. At some point the front brake on the non drive side must have received a knock and was pushed back towards the fork. This meant the back of the brake pad hit the wheel first and caused vibration and noise. I managed to push the braze on post back to parallel to the wheel. However for both sides, when I pull the brakes the back of both pads hit the wheel first, and everything vibrates. The pads look parallel to the wheel before I pull the brakes. I have no problem with the rear brakes.

The cantilever brakes have no way of adjusting the plane of the brake pad. The only way to change the orientation is:
- bend the post
- bend the arm of the cantilever (I haven't succeeded in doing this)
- fashion a washer to tilt the stem of the pad in the holder. I did this with a piece of electrical wire and it worked but I was very concerned that if I had to brake hard it might not hold, leaving the brake pad ineffective.

The other problem is that the replacement pads I have are too wide and I am obliged to align the cantilever arms way below the horizontal to fit them it. I have checked multiple types and they are all similar. I am sure doesn't help the problem. The only pair I have found that fit are on old pair of mafac ones that I have. But I need new brake pads for them, which cost almost as much as my bike is worth 😁

So I wondered if anyone had any idea of what would be the best course of action:
- replace the front cantilever brakes with something modern and adjustable
- try to find an alternative source of mafac pads (any ideas welcome)
- bend the cantilever posts so they are facing slightly towards the wheel so hopefully when I apply the brakes they touch at least parallel. I am really worried about damaging them. Plus that would leave even less space for the pads.
- fashion a washer by filing down one half of a 1 or 2mm one (is this even possible??) I see some washers available but they are larger than the diameter of my holder.
- only use the back brake 😉

Thank you for taking the time to read. My bike is not worth a lot but is lovely to ride and this whole issue is frustrating!

Photos below.
Many thanks
Gill

Back brake

Front brake with arms almost horizontal

Front brake before I bent the post back

Brakes for info
​​​​​​

Kimmo 

What sort of bars? If they're flat, maybe you could swap the brake and lever for a V brake.

andrewclaus

Some posts are replaceable. If yours isn't, look into replacing the fork. Is there a bike co-op near you? They'll have a bucketful of forks, and a bin full of posts.

I wouldn't mess around with cobbled-together parts, or a possibly cracked/fatigued part, especially on the front brake.

After you get that fixed, look at this article on adjusting canti brakes. It looks like your yoke is pretty high, and adjusting it lower will get you better braking. Especially with those plated steel rims.

Gillparis

They are drop bars. I had thought of replacing them at some point with a flat bar. But in the end it would be easier just to change the bike.

I don't think the post is replaceable. It is all one unit attached to the frame. I can check in the bike place for a different fork but I have never really seen any road bikes with cantilever brakes in there. They all have the normal ones. Their suggestion was to bend the posts.

Thank you for the article. I do have a shorter wire so I could also swap it if I solve the problem first.

JohnDThompson 

You could replace the calipers with ones that allow toe-in adjustment.

sovende

I have very near the same brakes on my '85 Miyata that I'm in the process of rehabilitating. The original pads (now 35 years old) are rock hard. I've purchased generic pads and will be installing them in the near future. I too, am anticipating installation issues. On mine, there are convex washers that I believe will facilitate setting the pads with a bit of "toe-in". I'm not seeing a washer of any kind on the ones in your pics. I'm going take pics of my installation and will eventually post the pics and a narrative (if and when I achieve success!)

ClydeClydeson

1. Your story of bending the canti post to align the brakes is giving me heart palpitations. THe brake posts are a structural part of your frame and fork. Bending them is not desirable.

2. Other models of old high-profile canti brakes came with a bevelled washer that went under the post of the pad, and rotating this washer before tightening the pad down would change the angle of the pad.

3(a). My experience is that old 'high profile' cantilevers are pretty much crap compared to newer low-profile cantilevers, and complete crap compared to V brakes or mini-v brakes (direct pull brakes).
3(b) I recently overcame my chronic cheapness and replaced the MAFAC cantis on the rear of my bike with a cheap (like $12) set of Tektro mini-vs. Night and day difference. You would experience a similar improvement with a set of modern inexpensive Shimano low-profile cantis, which are much easier to set up as well, compared to your old Di-Yeung brakes from the bottom of the ugly pile. The new brakes also come with new pads, and are only slightly more expensive than a set of aftermarket pads alone.

https://www.bikedoctor.ca/product/sh...e-374611-1.htm

Gillparis

Thank you everyone.

sovende I will look forward to seeing your success story.
ClydeClydeson I gave myself heart attack and stopped that sort of messing about as soon as I left the bike place. I feel like replacing the calipers as they are in fact very ugly and a nightmare to set up properly. Thank you for your suggestions - I will have a look at the options. Quick question - are all posts the same diameter? So if I replace them will the spring and bolt that hold the calipers to the frame fit on my ancient model? I also understood that older forks are narrower and there can be difficulty in fitting new cantilevers.

Thank you everyone!
Gill

ClydeClydeson

New brakes will fit on the posts and will come with their own springs. Probably new bolts as well.

oldukbkr 

Like a couple of other comments above, I’m a bit concerned at metal fatigue from bending the post. You might consider replacing the brakes with side pull calipers, thereby taking the posts out of the equation. But you’d need to check there is room to fit them around rack and fenders and make sure you get long enough drop to reach the rim.

Gillparis

I had considered this. I will keep an eye on it for now, thank you for the reminder. The bike is probably older than me and will most likely still be here after me!

Gillparis

So sadly the bicycle will not be here after me, except in pieces. A close look at the cantilever post showed that it was very weak from the impact and being bent back so I decided to call it a day.

For information I tried the Shimano Altus cantilever brakes but the front fork is too narrow and they don't fit.

I will sell the bike for spares having removed the front brakes. Somebody could decide to change the fork, and I might check at the local bike co-op first to see if they have anything. Should I also break off the canti-post to be sure nobody tries to sell it on to an unsuspecting person?

Thank you for all your advice.
Gill

sovende

Moving on is/was prolly a good decision! While I had mentioned that I had a bike with a "similar" cantilever system, it's clear that the cantis on your bike have little, if any, "adjustability! Torquing on frame components is never a good idea. Cobbling up a solution might have worked but proceeding as you have will be better in the long run. Good luck!

Geepig

Drop the forks out and scrap them, then try to sell the frame - checking that the frame is not bent. I am afraid that I wrote off my brother's Sun in 1980, running it into the back of a car, but while it looked alright the guy at the bike shop showed me that it was bent.

It was a nice bike shop, just outside the gates of the former Norman bicycle factory.

I never told my brother, just scrapped it quietly.

Andrew R Stewart 

The basic issue with this fork is that the canti posts are (were?) too close together for the rim width and the thickness of the pads. One attempt of a solution I've done in the past is to grind down a pair of pads so the rubber insert is aprox half as thick. Andy

63rickert

In third photo there is some sort of flange/washer/nut on back surface of pad holder and it is hanging up on the thick washer of the eyebolt. Move the post in towards the rim one millimeter and alignment will immediately improve by five degrees. The thick washer can be filed with a small round file. File a groove at an angle and the pad post can be at any angle you wish without bending anything. That is why that washer is there and that is why it is thick. Also the straddle cable is way too long.

There are enough small problems here to disqualify the owner of this bike from being his own mechanic. DIY is like a religion, time to leave that church before an accident occurs. Many riders will do 99% of braking with rear brake only, it remains that the front brake is the powerful one. No front brake, no safety.

The story about bending the brazed post is terrifying. No way to know if that post is still safe except a hands on inspection by a mechanic. Preferably an employed mechanic with general liability insurance. The post might be fine. It might be possible to add some brass or the post could be re-brazed. With no inspection but by photo and observers far away the safe plan is a new fork.