Vibration during braking, input wanted.

[madsciencenow]

I have a buddy who owns a Ritchey Road Logic frame with an R8000 groupo. He's had several different sets of wheels on the bike from RB AL to CF (Enve 3.4 w/ 2nd gen brake track). On all sets of wheels, at higher speeds, he notices vibration coming from the rear of the bike. Is this a flaw in the design of the frame, normal (I've never experienced this with a steel frame), or something he's doing wrong in the set-up of the brakes? FWIW, he's adjusting the brakes so they are both parallel to the brake track and sitting at the same distance away. Thoughts on how to remedy would be appreciated.

[Mark McM]

Can you describe the vibration a little more? Is it a high pitched, or a low pitched shudder? Does the brake force 'pulse'? Does the frequency of the vibration change with speed?

As the description says that it occurs with multiple wheel sets, then I suppose you should start by looking at the brake calipers. Are the pads new or old?
Have they been toed in? Does/do the pivot(s) have play in them?

(I've had a steel Ritchey Road Logic for many years, and I don't have a rear brake vibration, nor do my other steel bikes, so I'm not inclined to think it is the frame.)

[slambers3]

There’s a lot of info missing here that could be relevant to the question at hand but I will throw out that I’d be highly surprised if the problem was related to with the frame itself. Is he swapping pads? Pivots tight? Brake tight to the frame? Cable/housing the correct length?
I rode a modern road logic for about a year and had zero issues with brake shudder (or any problems at all)

[rowebr]

Agree first have a look at the calipers and pads...maybe the pad holders are flipped upside down, or set up toe-out instead of toe-in?

[jds108]

Two things to do here that will fix this 99% of the time.

1- Toe in the pads (and make sure they're installed correctly)
2- Clean off the rim's braking surface. I'd suggest some kind of cleaning fluid + rag, mild scotch brite, then cleaning fluid + rag again.

[Veloo]

I was getting some shimmying on descents.
Went away when I refaced the head tube. On a CK headset the unevenness was just visible enough.

https://forums.thepaceline.net/showt...=reface&page=2

[madsciencenow]

Originally Posted by slambers3

There’s a lot of info missing here that could be relevant to the question at hand but I will throw out that I’d be highly surprised if the problem was related to with the frame itself. Is he swapping pads? Pivots tight? Brake tight to the frame? Cable/housing the correct length?
I rode a modern road logic for about a year and had zero issues with brake shudder (or any problems at all)

I agree that there is additional info that could be added and I'll try to get some of this. I'm inclined to think it's not the pads as he's had multiple different sets on the bike with different rims (AL and CF).

[Mark McM]

Also, this issue is described as "vibration coming from the rear." Does this mean it only occurs when the rear brake is applied? If so, that probably rules out the fork and headset.

[madsciencenow]

Originally Posted by Mark McM

Also, this issue is described as "vibration coming from the rear." Does this mean it only occurs when the rear brake is applied? If so, that probably rules out the fork and headset.

Yes, no issue on the front brake and I agree, the HS is an unlikely culprit in this case.

[madsciencenow]

Originally Posted by Mark McM

Can you describe the vibration a little more? Is it a high pitched, or a low pitched shudder? Does the brake force 'pulse'? Does the frequency of the vibration change with speed?

As the description says that it occurs with multiple wheel sets, then I suppose you should start by looking at the brake calipers. Are the pads new or old?
Have they been toed in? Does/do the pivot(s) have play in them?

(I've had a steel Ritchey Road Logic for many years, and I don't have a rear brake vibration, nor do my other steel bikes, so I'm not inclined to think it is the frame.)

He says it's low pitched and it increases with speed. Also said pulse is hard to say because he feels the vibration so strongly.

[BdaGhisallo]

Is this a vibration that you feel more than hear?

I've had this on some frames in the past where I could feel the whole top tube vibrating when I applied the rear brake. No amount of brake pad adjustment or changing compound would cure it. Some frames have it and some don't. It was definitely more pronounced on some of the more textured carbon brake tracks like the Enve textured rims and the Bontrager Aeolus XXX.

I had the builder of my next frame build with thicker walled seat stays and I haven't really had the issue on that frame. I can generate a little bit of vibration if I try to do a hard stop with only the rear caliper but the manner in which I normally use the rear and front caliper in combination doesn't produce it on this thicker stayed frame.

I found the issue was worse with newer and stiffer calipers. Frames that created annoying but tolerable vibration with DA 9000 calipers were ridiculous with the stiffer DA 9100 calipers.

[Peter P.]

Okay; so it's your buddy's bike.

Be a pal and swap rear wheels for a test ride down a hill. Doesn't matter if you two run different brand drivetrains; this test doesn't need gears that work, just a rim brake wheel that fits.

If swapping wheels makes the problem go away, then it's a wheel issue, possibly a bulged rim or a rim from wear or impact, or an uneven rim seam.

If the problem remains, examine the brake pads or try replacing them. Check the brake caliper for loose mounting or loose arms. Then check the frame for cracks, particularly in the rear end.

[JedB]

Since it occurs with multiple brands of rims....

If it's a Ritchey with adjustable drop outs, are both sides set for the same distance?

Then I'd move to the rear brake bolt - is the brake bolt through the stay tight?
If no, then tighten, and re-check for vibration.
If yes, then on to the pads.

When he feels the vibration, is there also a pull to the left or right as he brakes?

[rustychisel]

I feel Pete's response gets you a long way towards an answer.

I would check bearing adjustment and preload for the wheel in the first instance, even imperceptibly loose can cause the issue as described. Yes, imperceptibly, so snug the cones or squeeze the preload 'a smidge' tighter.

Then check QR for play.

Originally Posted by Peter P.

Okay; so it's your buddy's bike.

Be a pal and swap rear wheels for a test ride down a hill. Doesn't matter if you two run different brand drivetrains; this test doesn't need gears that work, just a rim brake wheel that fits.

If swapping wheels makes the problem go away, then it's a wheel issue, possibly a bulged rim or a rim from wear or impact, or an uneven rim seam.

If the problem remains, examine the brake pads or try replacing them. Check the brake caliper for loose mounting or loose arms. Then check the frame for cracks, particularly in the rear end.

[madsciencenow]

It's clear that some of you aren't reading the original post and while I appreciate the advice, it's not relevant.

I'll have him give the stepwise instructions a go and will toe in the pads to see if this helps (I don't think it's pulling to one side or the other and the distance to the rim is equivalent on both sides as is the vertical position of the pad on the rim when the brake is actuated). As mentioned earlier, it's not a wheel issue. Three sets of wheels both CF and AL and I owned the CF ones previously and rode w/ no issues. This is most likely a set-up issue or potentially a frame issue but I tend to think it's not as it's a mass produced frame (Ritchey Road Logic size 58) and while it's possible, unlikely that this is the issue.