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I have found an issue with my bike which has Guide R hydraulic brakes. Whenever the suspension compresses a lot the brakes bind slightly which cause the bike to slow down and an annoying squeak to be heard. This happens when hitting bomb-hoes and landing after some drops as shown in this vid:
Does anyone have any recommendations on how to fix this issue?
Thanks
How can you tell the brake is coming on when hitting it? Is it not tyre on frame? It makes a squeak too
Are all the bolts tight? Hose not fouling anywhere?
edit, just seen the video, I reckon that’s frame/tyre. How hard do you run your shock? What frame? Bossnut?
To me that sounds like a brake squeal in the vid, rather than tyre rub.
If you have a rear air shock, can you release all the pressure and bottom it out whilst pushing it along.
Should show the problem if so.
I'd guess it could be a tight hose that pulls the calliper slightly when the suspension is heavily compressed, or even a damaged frame twisting. Would expect a damaged frame to be more evident though.
You'd need to compress the hose a lot to get the brakes to apply!
I'd have thought its more likely to be play in the frame bearings / hub bearings
can't see hydraulics doing that; cable discs maybe
If it is a Bossnut, didn't the early ones have an issue with the rear tyre hitting the seat tube under full compression?
I don't think it is tyre rub as there are no marks on the fork or frame. It's a Specialized Enduro FSR. I think I do have the front and rear shocks running a bit on the soft side. I should maybe try dialling them up stiffer and trying that out?
Or, as posted above, let the air out so you can fully compress them easily and see what is actually going on.
Or just keep guessing and trying things until you nail it - your choice!
I used to have a fork that made that kind of noise when it compressed. Got louder and higher frequency the faster you went too.
But it does sound like a tyre/frame/fork rub to me 😀
Sounds like you need a new bike.
PMSL @NoBeer
#TurningDHintoanadventure
Seems more likely to be the tyre, but if taking the air out doesn't show tyre rub, check there's nothing cracked/loose allowing the wheel to twist under load.
Hub bearings shot?
Maybe try this: grab the frame. Grab the rim.
Now push the rim with force from side to side. There can be quite some deflection - that's fine.
But what's not fine: when you feel "play".
One possible source of "play": the hub bearings. If the bearing is an industrial bearing it might be shot (you need a new bearing then, 6 bucks or so). If the bearings are cup and cone you will be able to adjust them again.
I didn’t mean the hose actuating the brake normally, more along the lines of physically pulling the calliper with it if it is shortened when the suspension moves.
Depends how the hose is routed and if it goes slack or tight under compression of the shock.
Caliper is firmly bolted to the frame. It'd just yank the hose through the guides, or worst case rip it from the union.
Another vote for something rubbing the tyre. If it's that kid on a go pro I suspect it's easily be enough if a ton to make it feel like the brakes are on.
Any cables that could make contact? You really need to let the air it of the rear shock and compress it.
How far back is the saddle on the rails?
How much clearance on the tyre?
Has it always done it, or only recently started?
How far back is the saddle on the rails?
and have you got anything under it (saddlebag, spare tubes,... )?
Does the bike have a coil shock?
That sounds like the rear tyre to me. Do you have any kind of rear guard. e.g. Crud Catcher on your bike? A mate of mines bike used to do exactly that when the suspension compressed and the tyre caught his rear mudguard.
Had a hip surgery recently?
Having the noise only when biking - or also when walking / jumping?
Thanks for all the suggestions everyone. I will have a play around with the bike this weekend to see what I can find. I'm 99% certain it is happening on the front as this video shows it happening as the front hits the bottom of the bump.
The bike has only done about 200 miles since brand new so I hope there is no major defect, however the bearings might be a good shout as the video above shows it doesn't necessarily happen when the suspension is fully compressed.
Nice vid! Perfect trail, perfect weather...
Front:
RockShox Thru axle? Is this thing really "tight"? There is a tiny little hex screw (center, on the side of the "lever" of the axle" where you are able to adjust the "lever force". Thru axle needs to get "locked" and then the lever needs to "feel tight" when pushing the lever to "close". If not: adjust that little, tiny screw.
Bearing play, hubs: very easy to detect.
If play:
200 miles: warranty thing?
If not - and if hubs with thru axles AND "cup and cone": in the case of thru axles the cone nuts are quite big. To adjust these you will need quite big "cone hex keys"...(bike hub axle cone hex wrench). Size? Depends onto the hubs.
Thanks, it was a really good day but very cold and icy in places.
The fork is a RockShox Pike RC 27.5 with 15x110mm Stealth thru-axle. It may not have been mega tight so I will try and ensure it is. The front hub is a Spec Roval Traverse with sealed cartridge bearings so if it is the bearings then I will see about getting them replaced under warranty.
Brand new? I'd head back to the shop with your vid and let them find the issue.
The 'brake squeel' sound could well be a red herring though.
could be that whatever causes the backend to move in one piece (I assume there's a brace of some sort) is snapped/cracked, causing one side of the rear end to move more than the other, and the resultant twist of the wheel is causing the brake to rub? or one of the bolts holding one of the pivots together is gone and it's separated?
edit : having watched the vid - could it be the stanchions rubbing against completely dry bushings? might cause a catch-slip vibration that has the noise. I'm erring towards that as the sound seems the same at any speed, whereas you'd expect it to be different pitches at different speeds if it was wheel-rotation-related
Having access to a couple of Enduros running Pikes but now Lyriks I have had that noise with a new Butcher tyre on the front when landing when the tread has buzzed the fork.
I experienced something similar with an old set of SIDS (i.e. very flexy forks), with a dropout that was slightly off, so the wheel didn't quite sit straight. With anything bigger than a 2.25", the tyre would buzz on the brace/leg with a big hit, which had the effect of applying the front brake at the exact moment you wouldn't want it.
Check for wear to the paint on the inside of the fork legs, and while you're at it do the same on the rear to try and rule it out.
Very bizarre issue...
If you bought it from a local bike shop I would take it in for inspection.
If you bought it online and have a shock pump, I would release the air out of the shock and try and replicate the problem. check everything is tight. Axle, brake disc, caliper etc
Does sound like tyre rub but I guess it's one of a few possibilities.
Have you checked tolerances on your ringpiece?
#tommysqueaker
Hadn't realised it was coming from the front before - how long is the front brake hose? Could it be catching on the tyre when the fork compresses?
Might be worth checking in case the tyre's slowly wearing a hole in it.