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Basically, whilst out today I was getting a loud buzz on landing drops / jumps. It dies sound like the tyre rubbing the frame but guess it could also be the disc? The bike is an on one codeine and I'm running the standard 2.4 chunky monkey on the front. The obvious guess is that the wheel / tyre is deflecting upon impact and buzzing against the forks, although on quick inspection it doesn't appear to have left any marks.
What could cause thus? Badly tensioned wheel? Tyre pressure?
I'm guessing the tyre is fouling the fork brace.
My old chunky munky 2.4 on revs did the same.
might the rear be fouling the seat-tube when the suspension compresses ?
either way, take a look and you should see the marks
Buzzing the crown when the fork bottoms out maybe?
I'm almost certain it's the front. I'll have to take a better look tomorrow for marks. Would running low pressure make this worse?
The only time I had this a broken axle was the cause.
I wondered about the axle, I did tighten it slightly before the last descent but weirdly I couldn't say if it was better or not. Sounds daft but I just didn't notice if it was still doing it. I did have the front wheel off a day or two before the rude so could be a possibility. It's a maxle.
I had this exact problem a few weeks ago . I was convinced it was the front and it turned out to be the rear wheel flexing and slightly touching the chainstay . I had the spokes re tensioned and its been spot on since
Should have mentioned that both front and rear have slight buckles. I'll defo have to inspect it tomorrow and see if there are any marks
you don't by any chance have a neoprene mud guard stretched from crown to brace?
No, I did have a mucky nutz on there and that dud catch from time to time, but it bulges out and was very close to the tyre. I took it off a day or two ago before thus ride. Maybe it was masking the tyre buzz
My guess is you'll have tyre marks under the fork crown.
Not that then! Had that on my old Kona shit myself everytime it happened!! Cant say Ive ever had any issues with tyre buzz on my Codeine so I'm not going to be any use to you 😥
If it is catching the Crown what would the cause be?
Got to be the crown
If it is catching the Crown what would the cause be?
The simplest reason (Google for Occam's Razor) is that your tyre is bigger than the free space available when the fork is fully compressed.
So if you have a fairly large tyre, perhaps with chunky tread, it may be right at the same point as the "reasonable assumption of tyre size" that the fork designer made.
I have a "frankenfork" Rockshox that does this, but in that case its because it has a Judy crown and SID lowers which makes the free space on full compression a bit smaller than if it was a SID crown. I did quite a lot of riding with it, which was fine when I rode that bike a lot because I got used to it. Once it became a more occasional ride it would do my head in and I ended up swapping the fork.
Do you have a dropper post with an externally mounted cable? I got this on my bike initially. I even suspected a dodgy shock and sent it back under warranty - they did find an issue with the shock but I still got the buzzing when it was re-fitted. Anyway eventually traced it down to the tyre rubbing on the Reverb hose as it drooped down when the saddle was down.
You mentioned low tyre pressures. Sometimes if I'm running my front soft it can make a buzzing sound if the tyre completely deforms on landing. Especially if the landing is off-camber for example. But that would be more of a one off rather than every time on full travel.
Assuming you've got an air fork deflate it and see if the crowns fouls the tyre.
The tyre came as specced with the bike. It's a pike so I'll let put the air and see what happens. I don't understand why the space would be any less under compression though? the lowers are only piece and the wheel shouldn't move in it? Maybe I'm missing something?
Front brake cable sliding in guide and buzzing the tyre as forks compress (one random possibility)
Which way do you run the brake cable, inside or outside the stanchion? As said, compress can slide the cable through any guide to balloon out and rub.
Another one is don't cable tie the cable to the top of the fork. Done that and wondered what the rubbing noise was.
Other than that I had rubbing with a Neoguard.
It's a pike so I'll let put the air and see what happens. I don't understand why the space would be any less under compression though?
You're confusing buzzing against the underside of the steerer with the brace. Obviously if it was buzzing the brace, something real bad would be happening.
Letting the air out should at least let you know if it is the steerer/crown assembly that is the source. The hose issues are a plausible alternative reason.
I had a similar problem with my Fox 36's.In my case it was the brake hose guide on the crown turning slightly & just touching the knobblies on the outside of the tyre.
Do you have a dropper post with an externally mounted cable? I got this on my bike initially. I even suspected a dodgy shock and sent it back under warranty - they did find an issue with the shock but I still got the buzzing when it was re-fitted. Anyway eventually traced it down to the tyre rubbing on the Reverb hose as it drooped down when the saddle was down.
This is what it was for me when I had a similar issue. I was convinced it was the front too, took off the mudguard, etc to try and isolate it but turned out to be the rear tyre when the shock was compressed!
I do have a dropper post so could be this, although it has not rubbed before?
And the winner is..... dropper post hose. I've let all the air out if the forks and there is still plenty of space and can find no rub marks at all. Brake cable is also tight and doesn't get close to tyre. Dud the same at the back and the reverb hose dies touch if you rotate the hose guide. As thus is mega loose it's totally possible that thus us the issue. Only thing is there doesn't seem to be any marks on it but it was only on landings. Really odd as I was CERTAIN it was the front. Will only tell on my next rude but thanks guys!
dud thus rude 🙂
No worries, happened out of the blue for me too after ~6 months of riding!
No, I did have a mucky nutz on there and that dud catch from time to time
is it zip tied to the stanchions? 😀
Take a file to all the bits of the bike that are close to the tyres just to be on the safe side.
EDIT 😉
Do you have one of those inner tube mud shields between your fork brace to the crown? When I used to do that, landings would compress it then make a really loud buzz as the wheel tried to pull it under the brace.
The speed of sound is much higher in solids than in gases, so it's very common to think you're hearing a problem at one end of the bike and it's actually at the other!
neoprene mud guard? cable hose?