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Old mountain bike rim brakes


Question

I have old mtb which has v-brakes.

The rear wheel just wouldn't brake, I tried different pads, adjusting them, cleaning the rim with surgical spirit, but there is no effect. 

The wheel is from a newer bike which had a disk brake on it before, so braking wasn't an issue. The rim is quite thin. It's usual alloy material which had paint on it, now rubbed off by the brake pads. 

When I try to brake, even when when pressing really hard, the wheel just slides. 

Is it something to do with the rim material or width? Is it possible to get a pad with a different compound that will work? 

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Some wheels have 'dual duty' rims, these were sometimes fitted on disc hubs and were suitable for rim brakes.

Disc specific wheels are not suited to rim brakes as they are usually tapered rather than flat faced.

Brake shoes can also be a problem as the rubber material and rim combination can be a bit fussy along with the setup.

My old 1990s MTB is a bugger for this as I get very  little brake effort and a lot of noise.

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Posted (edited)
25 minutes ago, Chewing Grass said:

Some wheels have 'dual duty' rims, these were sometimes fitted on disc hubs and were suitable for rim brakes.

Disc specific wheels are not suited to rim brakes as they are usually tapered rather than flat faced.

Brake shoes can also be a problem as the rubber material and rim combination can be a bit fussy along with the setup.

My old 1990s MTB is a bugger for this as I get very  little brake effort and a lot of noise.

Thanks. There is some tapering but not much. Just wondering if there are any pads that are good for problem cases like this one.  

I've been using the bike mainly on towpaths so didn't really care about the brakes, but decided to resolve this after almost running over a dog that run out of bushes right in front of me

Edited by Bear Hug
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Your rear wheel does bugger all braking in the grand scheme of things. If you're only cruising around towpaths, take the caliper and lever off altogether and call it good.

Edited by AWW
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My money would be on a corroded or unravelling inner or poorly routed cable housing to the rear brake, so the force from the lever is not getting to the brake shoes.
A rim made for rim brakes doesn't have much extra meat to allow for wear compared to a disc-only wheel....just look at the depth of wear indicator on some new rims. And I've worn holes through rims and they were still functioning OK when I noticed. If you were using a disc-only rim and the rim walls were curved or not parallel with each other, that might reduce your braking ability a bit, but not by much (cos theta sort of effect) and the pads wear to conform. I'm using a rear wheel at the moment that came off a disc-braked bike. The braking surface was anodized but has now partly worn off. Anodizing is exceptionally hard and I wasn't sure it was intended for rim braking, but I don't like wasting money, and rim/brake combination has stopped me successfully for several years.

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1 hour ago, Nippy said:

My money would be on a corroded or unravelling inner or poorly routed cable housing to the rear brake, so the force from the lever is not getting to the brake shoes.

 

I had to replace the cable and cable housing on the rear brake of my 1990's mtb last Autumn for a similar reason. The cable housing was just gunked up and the cable a bit rusty. The noodle was gunked up as well - I cleaned that out but it would have been easier to have replaced it for a couple of quid in hindsight.

I bought a kit with all the needed bits from Wiggle for about £6.

https://www.chainreactioncycles.com/lifeline-essential-brake-cable-set-mtb/rp-prod155216

https://www.chainreactioncycles.com/jagwire-v-brake-noodle/rp-prod168230

The only thing with replacing the cables to think about is that you need a proper pair of cable cutters - wire cutters will not do it. I bought the basic Wiggle ones for £11 IIRC. Feck, £15 now.

https://www.chainreactioncycles.com/lifeline-pro-cable-cutter/rp-prod10187

If you go down this route - and have never bought from Wiggle / Chainreaction - you usually can find a code for £10 off a first order over X. They give free delivery over X anyhow so it often makes sense to buy all the bits you need in one go.

Edited by The Masked Tulip
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It made my eyes bleed buying the special cutters for cutting the cable and housing, but they are quick and convenient. Prior to that, I used a Dremmel cuting wheel to do a nice job of cutting and squaring the end, but it isn't quick, and it is fairly easy to melt the plastic.

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On 01/07/2020 at 22:44, Bear Hug said:

The rim is quite thin. It's usual alloy material which had paint on it, now rubbed off by the brake pads. 

 

Dedicated braking surfaces don't have paint on it from new. This is a disc brake only wheel and the rims are not suitable for rim brakes - you must get another wheel.

 

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1 minute ago, 201p said:

Dedicated braking surfaces don't have paint on it from new. This is a disc brake only wheel and the rims are not suitable for rim brakes - you must get another wheel.

 

I meant to update a while back but better late than never...

I tried a different (definitely not disc brake only but still quite narrow unfortunately) rear wheel and braking was only marginally better.

The brakes are old, they are calipers mounted on the frame, not even v-brakes.  As I have another bike that I use for trails with tyres so thick that they touch its old v brakes, I have upgraded that bike's vs to a newer bigger model, and I have taken the vbrakes from that bike and installed them instead of calipers. 

It's much better, even with the unsuitable disc brake wheel. Cheap clarks brakes set fits perfectly to my trail bike. I did have to replace the caliper brake handle for the dedicated v brake handle as the caliper brake handle doesn't pull sufficient length of cable to be used with vbrakes. 

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21 hours ago, AWW said:

Your rear wheel does bugger all braking in the grand scheme of things. If you're only cruising around towpaths, take the caliper and lever off altogether and call it good.

I have been over handle bars and on the ground at least 4 times after braking too hard with front! I have a slight preference for using rear ones

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On 24/07/2020 at 19:16, Bear Hug said:

Just clarify, the bike had caliper, not v brakes stated in the original post. I just didn't know the difference, now I do

No,  you still don't!  I doubt you could upgrade a bike with calipers to V-brakes. An old 1990s MTB would have cantilever brakes. These are actually pretty decent when set up right.

Caliper brakes aren't seen on MTB, and they look like this:spacer.png

 

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42 minutes ago, Nippy said:

No,  you still don't!  I doubt you could upgrade a bike with calipers to V-brakes. An old 1990s MTB would have cantilever brakes. These are actually pretty decent when set up right.

Caliper brakes aren't seen on MTB, and they look like this:spacer.png

 

Yes, sorry - cantilever! That's the one. 

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