ARC and discs

[mik]

OK, been meaning to ask this for ages.
I have an 03 ARC. Ran it with V brakes for ages, but I was finding that my v's weren't really doing it for me, lacking in power... dunno, poor setup, pads/rim friction, not sure never had a problem before... so easy excuse to buy new stuff and future proof parts for a new frame...
Anyway I managed to get some Avid juicy 5's and some mavic wheels off a mate for cheap and they gave me better stopping power than my V's but they gave a terrible vibration through the bike. I put this down to the avids, tried fiddling with them no end but nothing worked. Was driving me crazy, was about to buy new brakes but my guy at the lbs had a look and discovered that all it was was the seatstay was flexing under the load causing the vibration when it sprang back.
Pulled the brakes off, put them on my zaskar, no issue. (160mm front and rear sized disc)

So I am about to buld up my xizang with the v-brakes and was thinking i can either buy new v-brakes for 1 or the other, or new discs and wheels for the arc... but if they are flexing then it will be useless...well not useless, just noisy and... very uncomfortable for any part of my legs/neither regions touching the bike.

Has anyone else had an issue like this?

[FF]

Hi Mik,

I have a 98 ARC with entry level mavic wheels and Avid Juicy 7 brakes with 160 rotors and don't have an issue.

My older frame has the extra 'detailing' at the top of the set stays which may help reduce / eliminate vibration of course ? I think this feature had disappeared by 03 and the frame was back to a conventional looking seat stay setup.

Not sure that is much help to you though !

Fred

[Andrew]

I had an 04 which was essentially the same as an 03, never had any issues.

[mik]

hmmm doesn't help at also it was only more a problem when draging the brake or mid power, think it was fine when you really wanted to stop.

[Andrew]

My big top does that. I changed the pads and all ok.

Try getting the bike shop to face the disc mount face.

[Andrew]

That's the mount on the frame.

Did you try a different disc brake?

Pulling the brake on stationary should not make the stays flex. Unless one of the pistons is sticking, or you have those budget one piston brakes from Hayes or similar.

[mik]

Um. I mean that when you put the brake on, and then move the bike forward, the stay would flex.

[Andrew]

That's odd.

[mik]

maybe i'm just too hardcore (fat)...

[bagpuss]

Or maybe your frame is bent and needs truing! Sounds like the stays aren't aligned and the rear triangle is flexing.

[YetiPaul]

Had exactly the same issue with rear disc and avids on 2010 ARC, went with new pads and a full bleed remounted and all has been ok since,

[mik]

well years later built up my ARC again, transfered some XT brakes onto it, and no issues whatsoever, so yay... now to put a proper drivertrain on it and get it back into action...

even set a PR on a strava segement and I haven't jumped this much in eons haha...