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Weird Back Wheel.


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So I hadn't even TOUCHed the wheelbuilds since I bought it complete in January.

Jesus... Doesn't seem like a year :|

...Anyway - a couple weeks back, every time I put some power down, I got this horrid grinding noise.

Moved the pistons out and just bunged the TPA all the way in for the rest of the ride.

Leave it over Christmas, as I forgot it was dying - and then came to ride it the other day.

I tightened everything evenly, (why did no-one inform me it's so soothing to sort a wheel out? I really enjoyed the process this time around :) ) and even got that elusive buckle out that was there, then not, and then there, then not... etc. [/2nd_ramble]

It feels infinately better. I hadn't realised just how bad a shape it was in. Feels more springy, flicky, and controlled :) All from a tighter wheelbuild, and a few extra PSI.

Now - the problem is, I'm still getting the grinding noise every now and then. Not NEARLY as often, but when I really go for it...

The spokes are tight enough that I wouldn't want to tighten any more, for fear of stripping the threads.

Slave prongs are both about 2mm away from the rim, which is now absolutely buckleless (to me - within 1mm... hell - I'll bend over and blow my trumpet - HALF A MILLIMETER).

Now it's not really a problem, as I can go full out for a sidehop, and it's fine - just occasionally on starting a rolling gap's runup. (Rollup/rideup?)

Before you cunning little buggers point it out - I know it's time for some new pads... But I'm skint :P These ones that are so dead are KoolStop Reds that I found in the bottom of my spares box, and I only moved onto them 'cause my Magura Blacks suffered the same fate. Heh :$

Any help offered would be very well recieved :)


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Sounds like the wheel's flexing over a little bit when you pedal. Usually happens with bigger wheels.

All I can think to do is tightne the spokes up a little more. I have mine tight enough so when you squeeze a pair, they barely move! :P

You could cut the prongs down a bit too, as long as they still hold the pads in place, it shouldn't be a problem!

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Most people have the pads set about 2mm from the rim, and not get rubbing on the pads when they pedal hard.

Most people don't run pads worn enough to allow the guide forks on the piston to stick beyond the surface of the pad. Chances are you've had to move the slave pistons in closer to the rim than they'd be able to get with new pads to deal with the wear too, so that's the second part of how wear is contributing to the grinding...

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prongs are both about 2mm away from the rim

Chances are you've had to move the slave pistons in closer to the rim than they'd be able to get with new pads

Unless I'm missing something, that's not what I meant.

The pads are about 3.5/4mm from the rim - loads of TPA to make it work.

I'll check my dropouts for cracks when I get home.

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If the prongs are 2mm from the rim and the pads are 3-4mm from the rim then the prongs are the first thing the rim touches when the wheel flexes over. Most people don't notice this flex because if the rim touches a brake pad the noise and drag aren't that noticeable compared to the metal on metal sound of a prong hitting...

Edited by psycholist
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Take off all your tpa and "over bleed" your brake, set your slaves quite far out so they are nowhere near the rim, when bleeding the brake squeeze the syringe(sp?) so the pads come furthur out and put allen keys inbetween the pads and the slaves, unscrew the bleed kit, put all the bolts in places, take the allen keys out and your pads should stick out, this will work, but not for long, just get new pads :P.


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i allways used to grind down the prongs on the magura pistons, to allmost half the length, they still work fine and dont get the grinding noise, be carefull not to take too much off though because sometimes the backings come off you pads, and it hurts, ! lol


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