Cantilever brakes - excessive pad wear

[nez]

Thanks. My Galaxy has drops and brifters so I think mini Vs are out. I have shaped out the Oryx for better cantis (tektro 720 - I've checked) and of course the setup is critical.....

Tektro 720 will only be more powerful than a badly set up Oryx. A well set-up Oryx (with matching lever) ought to be almost as powerful as a V brake.

Depending on the model of STI you have, they might be better suited to cantis or mini-Vs.

cheers

you’re too polite to say ‘operator error’. I’ve had a look at the rather brilliant Park video at setting them up, have taken them off and cleaned them and am now off to try them out. Since I live on top of a big hill this might be my last post

[mcshroom]

Looking at pictures, I think the 2008 Super Galaxy had Tiagra-4503 shifters, so I think that's SSLR?

I did find the NSSLR R2030 lever worked better with the mini-v than my older 2303 ones. I was pretty happy with the 2303/RX5 braking though. The improvement was in pad clearance of the rim and how fiddly the set up was.

[nez]

Thanks Mcshroom
Well, following the Park video the brakes are much improved and I'm alive and kicking. So I'll be sticking with the 720s. The problem seems to have been having the spacers on the wrong side of the mount so the pad/arm wasn't horizontal at the beginning of the pull. In fact this puts everything slightly out of whack and leads to the rim pressure from the pad lacking a tiny bit - enough to make them hard work. I write this here so anyone else having the same problem can find it. The video is at [youtube]https://www.youtube.com/watch?v=G_tDym0G6zo[/youtube]
ps what's SSLR mean?

[mcshroom]

Glad to hear it
I thought 720's looked nice on a touring bike, I just wish I could have solved the judder.

SSLR is Super Shimano Linear Response. NSSLR is New Super Shimano Linear Response.

As I understand it, NSSLR levers pull a bit more cable when braking than SSLR ones.

[nez]

Glad to hear it
I thought 720's looked nice on a touring bike, I just wish I could have solved the judder.

SSLR is Super Shimano Linear Response. NSSLR is New Super Shimano Linear Response.

As I understand it, NSSLR levers pull a bit more cable when braking than SSLR ones.

Yes I don't get judder, it's just that the first thing I do when I leave home is stop on a steep give way with a busy road. One of the videos I watched suggested judder was more likely when the brake hanger was a long way from the cross strop between the cantilevers. Apparently arranging them so you can shorten that distance stops it. Maybe you can get long brake hangers - I don't know.

[pwa]

Glad to hear it
I thought 720's looked nice on a touring bike, I just wish I could have solved the judder.

SSLR is Super Shimano Linear Response. NSSLR is New Super Shimano Linear Response.

As I understand it, NSSLR levers pull a bit more cable when braking than SSLR ones.

I replaced Orycx with 520s (like 720s now that I have slide-in brake pads) and the key to judder-free front braking was an uphanger bolted onto the fork crown instead of a downhanger at the top of the headset. The 520 is a neater, classier looking thing than the orycx and it works well for me. I'm using non-STI levers so maybe that makes a difference.

Something like this should fix the judder. https://www.sjscycles.co.uk/brakes/rale ... le-hanger/

Spa sell the same item and say it can reduce or eliminate brake judder.

[cycle tramp]

[quote="brooksby"]My latest acquisition has centre-pull cantilever brakes (threadless). My previous bike had V-brakes.

I'm not aware of using the brakes any more than I do on my other bike and have only done maybe 500 miles on these pads, and yet the rubber has pretty much gone on one of the front pads (which seems really low). [/quote)]

H'mmm... apologies, I've put your word 'one' in italics just so I fully understand the situation.... from how it is written I understand that just one of your front pads is wearing at a higher rate than the other...
...which is less than ideal. If that is the case then it could be something to do with how the brakes may have been set up. Cantilever brakes can be more finicky than some others (trust me I've wasted more than a couple of hours in the garage attempting to set them up so that they behave in a reasonably manner*)
If one pad is wearing faster than the other then we could be looking at something like uneven spring tension.
Any chance of some photographs?
And would you mind trying something, pop out to your bike and give the front brake a squeeze, when you do so is one pad making contact with the rim first? And when you let go of the brake lever, do both pads move away from the wheel rim?
.....(* in the end I gave up and bought a nice set of drum brakes.... not as powerful as discs but perhaps less demanding to maintain........oh the controversy)

[mcshroom]

Yes I don't get judder, it's just that the first thing I do when I leave home is stop on a steep give way with a busy road. One of the videos I watched suggested judder was more likely when the brake hanger was a long way from the cross strop between the cantilevers. Apparently arranging them so you can shorten that distance stops it. Maybe you can get long brake hangers - I don't know.

I tried a few different heights, but it just didn't want to go on that bike unfortunately.

I replaced Orycx with 520s (like 720s now that I have slide-in brake pads) and the key to judder-free front braking was an uphanger bolted onto the fork crown instead of a downhanger at the top of the headset. The 520 is a neater, classier looking thing than the orycx and it works well for me. I'm using non-STI levers so maybe that makes a difference.

Something like this should fix the judder. https://www.sjscycles.co.uk/brakes/rale ... le-hanger/

Spa sell the same item and say it can reduce or eliminate brake judder.

That was another item I was thinking of trying, but I had a fork crown mounted dynamo light, and I couldn't see a way of getting everything to play together nicely using one. As it is, I cracked the down tube on that bike, so it's no longer usable I'm currently musing over the replacement, including canti/mini v & STI or bar ends and V brakes or discs, but I should probably start another thread on that

[Brucey]

uphangers work to stop judder not because of the shorter distance per se, but because the flexing of the steerer is taken out of the equation.

FWIW if you have juddery cantis, it significantly increases the risk of the frame cracking and the place it is most likely to crack is the down tube.

FWIW brake block wear can be caused by a piece of grit/flint/metal trapped in the brake block; this wears the rim and the rim in turn wears the brake block. Often the piece of flint is driven further into the brake block as the brake block wears, so the only sign it was ever there is that the brake block (and the rim) are badly worn on one side (or both).

cheers

[9494arnold]

What Brucey said. I periodically check my blocks and dig out the stray bits of metal/ stones that get embedded . Particularly if the pads have grooves, surprising how much detritus can gather there. And it might be worth checking your rim, particularly at the joint. I have on more than one occasion sanded a step out of the joint. Which improved braking no end. And there's another thread about the Mechanical Advantage and how high or low you should have the straddle carrier. It's a minefield. I run fairly old school cantilevers on Trikes (2 Brakes in front wheel) and have pretty good results. I use Aztec and Kool Stop Pads .

[Brucey]

IIRC there might be such a thing as a combined uphanger and dynamo light mount....?

cheers

[LuckyLuke]

IIRC there might be such a thing as a combined uphanger and dynamo light mount....?

cheers

Hi,

I've not seen a combination of the two. Would've helped me out on one build. I used a light mount like the one below in conjunction with a separate uphanger.

https://www.sjscycles.co.uk/lighting-sp ... er-brakes/

On the bike I fitted it to there was just enough space for the straddle wire hanger, between the bottom of the uphanger and the top of the light bracket. This was on a tourer with 38 mm wide tyres and guards. Brakes were shimano mid profile cantis, which work well IMHO.

The uphanger had a barrel adjuster built in which was useful. Worth seeking out.

Best wishes,

Luke

[brooksby]

For those completists out there, the conclusion to my story:

I've taken the front brake blocks off, and I can now clearly what the problem is/was.

Badly fitted brake pads ie. "User error"

The right side brake pad was closer in than the left, and (therefore) much, much more worn than the left, and is much more worn at the front than the back (to the point where what I had thought might be a piece of metal embedded in the pad is actually the exposed carcass of the brake block itself!). The wheel rim looks fine, as far as I can see, luckily.

I know that this was the first time I'd fitted canti brake blocks, and I remember trying very hard to set the toe-in, and I suspect that I've toed-in a bit too far...

So: clearly a case of (serious) user error, and I promise that I will try to learn from my mistake

(I've now replaced both pads, and tried to take a bit more care over it...).

[Brucey]

IIRC there might be such a thing as a combined uphanger and dynamo light mount....?

cheers

Hi,

I've not seen a combination of the two. ...

I've looked and I'm dashed if I can find one now... maybe it was wishful thinking....

To me, the 'canti' type B&M lamp mounting looks like it won't last forever; the stresses are very high at the first bend and I suspect this is where a crack might start (I've seen shorter, beefier-looking U-section brackets fail just there). It almost makes you want to tie the lamp bracket to the uphanger somehow...?

cheers

[mcshroom]

From experience that's exactly where they crack. In my case it chose to happen when I was riding downhill in the dark.

I switched to the mini v around the same time as replacing the mount. The mini v allowed the use of a normal 'bent wire' style mounting bracket.

PS: Brucey - yes the judder might affect the down tube, but not as much as putting your bike on the roof of a car and driving into a multi-story car park The crack started from the dents I put in then. The frame did last another 4 years after that incident though.