Strange rear v-brake judder

[MountainSide]

Suddenly started happening. When using the rear brake, it will start/stop judder. So i'll be moderately braking and rear will suddenly lock-up.

I've checked the wheel, looks to be reasonably trim. I've had problems in the past with out-of-trim and broken spokes so I know what that feels like - I just have to release the cable and adjust accordingly but it still would brake properly and not judder.

The pads are only about 1/2 worn. One side has a bit of an unworn bottom edge as if they were not seated properly. I sanded down the edge a bit and cleaned the rims but it still judders. Again I have had the unworn edge before but only noticed when they were totally worn as they also haven't previously caused a judder.

The cable and brake arms are all centered and returning properly and there aren't any loose bolts.

Unfortunately, I didn't have any spare brake pads to replace so have ordered some. However, i'm not convinced they are the cause of the judder. Does anyone have any other suggestions to check or is it most likely to be the pads?

Thanks.

 

[iluvmybike]

Sometimes when pads get a lip on them from running slightly under the rim then they can stick on. Might be worthwhile fitting a new pair. Odd that they lock up though - is the cable jamming somehow?

 

[Illaveago]

I was wondering if there might be some wear in the brake pivots which may cause them to jar when applied. Are the pivots greased well?

 

[MountainSide]

I was wondering if there might be some wear in the brake pivots which may cause them to jar when applied. Are the pivots greased well?

Probably not greased well. Although they do seem to be returning properly. I did have a problem with them sticking a while back and took them apart and cleaned which worked then - didn't cause judder then, just impossible to get the left/right balance (spring adjustments) to prevent pads rubbing until cleaned. Will give them another clean and look into where it needs greasing.


It's a hybrid/mountain bike by the way. Hope to get the new pads tomorrow.

Will provide update. Thanks for replies. Just hoping the wheel is ok as it's not that old. Just had a huge amount of fun extracting TWO spoke nipples from inside the rim that would rattle at low speed. When I removed the tyre pressure they got caught and no longer rattled, so were difficult to remove - removed the 1st one put everything back together only to realize there was a SECOND one! (and yes all the spokes still have their own nipples and the bike shop that made the wheel normally know what they are doing!!)

 

[MountainSide]

Sometimes when pads get a lip on them from running slightly under the rim then they can stick on. Might be worthwhile fitting a new pair. Odd that they lock up though - is the cable jamming somehow?

Bingo! Just had another look. The lip was causing the pad to slip down the rim slightly and stick temporarily when the brake was applied moderately. I just filed off the lip completely and again strip down, clean and greased all the brake parts. In doing so I remembered greasing them last time, so no problems there. Now working great. Will fit the new pads as soon as they arrive regardless.

So not so strange after all! Thanks everyone.

EDIT: Oh and it is great not having the spoke nipples rattling around inside the rim anymore too.

 

[MountainSide]

Realized that although it was better it still wasn't 100% even with new pads so took it to the local shop. They trued the wheel even though it wasn't out by much but this still made no difference. May or may not be a coincidence but when applying the brakes, it is at exactly the point on the rim where the tube valve passes the brake pads that the brakes will lock. (Maybe that was a weak point?) Is as if the rim has bulged out very slightly at the point of the valve hole, so it pushes more against the brakes on BOTH sides at the same time. They did say it wasn't as bad when the tyre pressure is released. So either live with it or get a new rim or they did say I could try sanding down the rim a little?! Anyone heard of this problem before, with a Mavic rim?

I do wonder if one of the spoke nipples that was loose inside the rim at some point got into a certain position that caused something to bend slightly either when the tyre was inflated or deflated? (They only tended to rattle around when the tyre was pumped up)

 

[MountainSide]

Having read numerous blogs about these Mavic rims cracking around the valve hole, I decided to check mine. Big crack either side of the valve hole. (in the metal that sits under the rim tape) Obviously enough to move the rims far enough apart to lock the brakes up after just a few hundred miles of light duty. Contacted their so called "customer support" only to be told they have logged it for me but there is nothing they can do as Mavic rims fail for "a number of reasons" as others have also described in the blogs. Not even an apology for any inconvenience.

 

[Ajax Bay]

Perhaps you could share what type of 'Mavic rims' these are? Rims have a finite life and my rear MA3 622-15 rim failed with several cracks around about 3 of the spoke holes (rear wheel). I replaced (and relaced) the rim (with a Mavic Open Sport (now styled Open Elite)). But I agree that cracks from the valve hole seem odd - there should be no stress there (cf spoke holes).