Cantilever Brake Masterclass

[Iwasgoodonce]

I’m in need of one! I went mountain biking yesterday. It was an eventful ride. I had some issues, all of them cantilever related. I remember them being quite good back in the day. They could bring me and my bike to a skidding halt with minimum input. I would adjust them and they worked.
That is a long time ago. I’m fully aware that I weigh a “little” more these days but that can’t be the only reason. Yesterday they rubbed from the off on the rims retarding even further my feeble forward motion, only one side would move much despite much wielding of a 2mm Allen key and, when applied only minimally slowed me down. Oh, they also went through the sidewall of the tyre. D’oh. In my defence this occured too far into the ride to have been rubbing from the start. I heard a rock like CLANG and then rub, rub, rub, BANG!
I think setup is the problem. It isn’t because I am used to modern disc braking. I still haven’t got around to trying them. Dual pivot road brakes and V brakes on my sort of touring bike are as up to date as I have. Someone (thanks Carl) set these up for the Cannock Turkey Twizzler. That one brutal ride saw off any adjustments he made.
I thought this thread could be a resource of advice and tips. God knows I need them; others might benefit as well. Here is what we’re starting with. The front:



And the rear:



Different straddle arrangements. I remember having the rear set up previously. I always wanted those CND style hangers but couldn’t afford them. Haven’t seen them in a while.
Over to you guys. I don’t do MTB enough to avoid every brake setup being my first in ages. Brakes are 1990 XTII and are the very brakes I had back then. Levers are Suntour XC Pro. I do believe the front cable is an original 2mm cable from way back too. Thanks all.

 

[FluffyChicken]

Wide profile canti's, I'm not so familiar with getting the best out of them low profile are easy though.

So I don't like straddle hangers as you can see they have slack (curves) that just take power (really modulation) away ;-)
Did you follow the instructions as provided. That's you first step.
The V brake style heads are thinner,. So you need to adapt them for the thinner heads.

That rear doesn't look like it likes the wide profile setup,. With the normal blocks, the blocks are near tight up against the block head, ( low profile are the opposite), is this the tyre rubbing one, I've forgotten and on mobile so looking backs a pain

It could be your springs are also buggered, they also have an slr/normal position which really just alters spring tension. SLRs have return springs in the levers..

Have fun.
Once that's done you can tweak straddle height to get the modulation you like.

Of course clean pads, rims...

Some thoughts, can attach the instructions if you want.

There

 

[FluffyChicken]

.Looking at the rear

Get a new cable when you can, you can see twists and bends and flat clamped parts
Move the fix length down a notch.
You can see the brake is at the wrong angle as it's bending the head.
Clamp the pads further in.

XC Pro have a return spring in the lever, iirc. But I would try it in the normal position at the back of the canti.
Clean everything.
You can always try a low tension later for a better light usage

Front
Avoid this, it's subtle, but keep at as straight as possible when it goes in.

 

[FluffyChicken]

I'm sure others will have other opinions too.

 

[Takingabreak]

Pulling up a chair, I'm woeful at setting up cantis despite good advice given on this forum. My first thought was that this topic has been covered in depth multiple times over the years on this forum but the search engine doesn't seem to find them

 

[JCS]

Check out the Park Tool cantilever brake tutorial on YouTube - it’s really helpful and easy to follow.

 

[R-V]

Very beautyful frame, what is that?

 

[legrandefromage]

As the self appointed God of Cantilevers I have to ask, what brake levers are you using, what cable stops etc

 

[Iwasgoodonce]

Thanks everybody. I’m about to order some new blocks. I’m going for Koolstop Eagle 2s. Any good? I remember the brakes working well with shorter blocks.
The bike is a Saracen:



Which at this vintage used full length internal outers for the rear brake. Ignore the rear tyre, something more suitable (and narrow) is on order. XC Pro levers @legrandefromage

 

[hamster]

There are two issues with cantis - firstly loss of force and secondly mechanical advantage (leverage).

Canti cable tensions are higher than Vs and a smooth cable run with gentle curves really makes a difference in reducing frictional losses. For example, shorten that rear outer into a smooth curve from frame stop to the seatstay. At present it's an S-shape - 3 curves giving frictional losses when you only need one.

The mechanical advantage one is more subtle and the reason most people ditch cantis. The cable pull needs to draw the cantis together, and the longer the straddle cable the more effort goes into pulling the cantis up rather than apart. Consider a tensioned car towrope - it's still quite easy to pull it upward, so a high tension has little sideways effect. Thinking in reverse, if the canti straddle is too long, then very little of that cable tension force is actually squeezing the pads together. Those fixed length straddle wires are awful. They were made to avoid the risk of an unattached straddle cable locking the wheel. Fit a cable yoke system and then set the straddle cable low. However, you cannot avoid the problem of the pull changing as the pads wear. Easiest is to fit v-brake pads in post mount holders, then you have thinner pads.