Mountain Biking - New Fuel EX8: Buzzy Juicy Five rear brake

I clock in at 235 lbs. When going down a steep paved slope I have to apply quite a bit of force to the rear brake or the pads vibrate the entire bike. Front brake doesn't do this.

Quick fix? I can take it to the shop I bought from, but would like to develop some understanding about this brake mech.

Thanks

Mike

go to mtbr.com and look up the review for the juicy 5s. There is somewhere between 1000 and 3243254345234 different remedies for the same problem, your success may vary.

Basically you're a big guy, and somewhere in the brake interface something is vibrating which may have to do with bolt/spacer length, rotor alignment, pad alignment, air in the system, rotor size and shape, alignment of the moon, etc.

I had the same problem with my 5s. I really really tried my best to like the brakes, Avid even warrantied mine with a brand new set, but I ended up switching to Shimano and never looked back.

Bahhh!
I had hoped I'd bought a bike that wouldn't require any upgrading but viewing that page it looks like I didn't hit the mark. I'm betting the positive reviews are from "flyweights".

I'm not going to screw around with this. Where can I find the best bargain on a complete XTR setup to replace the Juicy Fives??

Thx

Mike

My juicy fives have been just fine.

My shimano XTs are sometimes a hassle.

I just bought an 07' Specialized Stumpjumper FSR Comp and it comes with the Juicy 5's. I didn't notice anything until just recently after about 4 rides (have had bike 1 week). Now the rear brake vibrates and squels under light to medium pressure. The front brake does too, just not as bad. I have heard of other people having problems with this brake so I'm not sure if your weight has anything to do with it, I have the same problem and I weigh 173lbs. I read that wiping the rotors down with rubbing acohol can help, we'll see, I'm gonna try it.

What a coincidence. I was just reading a review of some brakes (Formula Oro Puro) and came across an interesting paragraph. Emphasis below is mine.



The other noise problem is far worse, but based on my research is not the fault of the brakes at all. The rear K-24 brake on the Trek Fuel sets off a resonance in the frame and the entire carbon fiber structure of the bike becomes a sound board. I can actually feel the vibration in the saddle and grips on steep descents when I am braking hard. And it is LOUD. A quick Google search reveals that most Fuel owners have this problem, hopefully Trek has fixed this in the few years since my bike was made because it is annoying. In trying to troubleshoot it, Greg at Formula USA did share one piece of useful info, even though it turned out not to by my particular issue – he suggested having the disc tabs faced, and said that this solves the majority of the squeal problems that they had seen. Turned out not to solve my problem, but it is good to know. In any case, the other 3 sets of brakes don’t howl so I am chalking this one up as a bike design flaw.

Here's the full article: http://forums.mtbr.com/showthread.php?t=221840

Sounds like it's a Fuel thing more than a specific brake thing. You should definitely head over to Mtbr.com forums to start searching for a solution to your specific problem.

LBS says they will enter a complaint with Avid who will promptly ship out a new rotor and discs. They say this has fixed the problem for some other J5 owners.
I'm not holding my breath, but it costs nothing so we'll see if it works.

Thanks for the input

Mike

My juicy fives have been just fine.

My shimano XTs are sometimes a hassle.

Wanna fight?:p

I really really really really tried to like these brakes, especially since I had so many friends that loved their juicy 7s (I know, they share a lot of the same parts), I just never got the level of performance I expected for the price. I'm not saying they're outright bad, but it seems like it's a pretty hit or miss experience for the consumer.

I stopped by Red Rock cycles while on a business trip today and told them about the problem. I left the bike with them for a few hours and they fitted a pair of Cool Stop pads and the problem seems to be solved.
I'll see if it's a lasting fix. If so I'm a happy camper.

Mike

But I believe the issue of noise is caused by any "play" in the wheel bearings. Tight wheel bearing nothing can resonate, with play the wheel play resonates and makes noise.
Check to make sure you have no play and skewer is tight.
j

but now the chatter is back again. I guess I'll haul the bike back to the LBS and ask them to please make my $1900 bike something that can be enjoyed.

I'm wondering about dremeling some diagonal grooves into the face of the pad. Maybe that would ease the chatter?

Bah!

It won't do a thing.

Switch the rotors to a hayes, shimano, or a hope rotor, and the squealing or vibrating will stop.

So you are saying I can switch the rotor but leave the brake itself as is?

Thx

Yes.

I clock in at 235 lbs. When going down a steep paved slope I have to apply quite a bit of force to the rear brake or the pads vibrate the entire bike.

Do you currently use the Polygon rotors or clean sweep?

Polygon rotors have a pulsating feeling under heavy braking. Lightweight riders won't notice it as much as someone your size b/c there is a great deal more braking force involved.

surprisingly, my Avid Juicy 3 stop squeling, Oo

Switch the rotors to a hayes, shimano, or a hope rotor, and the squealing or vibrating will stop.

Sigh, that didn't help me out at all, though a lot of peole have solved thier problems through this route.

Is your rotor the new G2 CleanSweep rotor? Cause they eliminated the annoying sound that caused many riders complain. Anyway have you check your caliper bolts? It could be loose

Yeah, looks like this one. http://tinyurl.com/2ywrwo

Guy at the LBS took off the new cool stop pads and installed a new set of Avid organic pads. Buzz is gone again, but there are hints of sqealing. I'm thinking the buzz will be back in a short time.

Next step will be to try a new rotor. I'll buy it from the LBS on the condition that they take it back if the problem persists.

A poster above felt that the genesis of the harmonic is in the EX8's chainstay/seatstay design. That's a possibility that is on my mind as well.

Thanks for the replies



Is your rotor the new G2 CleanSweep rotor? Cause they eliminated the annoying sound that caused many riders complain. Anyway have you check your caliper bolts? It could be loose