unexpected rolling with locked brakes

[Capricorn]

Heyall

 

Not sure if this is normal, but I only noticed it after I felt a 'weirdness' in the rear end during a DH session:

when i lock the rear brake, i can still rock the bike backwards and forwards. I'm pretty sure that previously, I couldnt do that, but I'm not 100% if I'm remembering correctly.

Is this normal or is something the matter?

[Capricorn]

ok. had a thought about it, and i'm 100% sure it didnt happen when I just had the rear hub replaced. The rotor doesnt move a stitch, but the hub turns a little. Any ideas anyone?

[Johan Bornman]

The bolts or the centrelock that holds the disk on the hub is loose or damaged.

[Capricorn]

ok, will have a look at that. thanks for that

[Mudsimus]

You can fix it by tapping the rivets on the rotor with a hammer and a punch.

[Capricorn]

had a closer look at it, in conjunction with the LBS techies, and it seemed me like there was some play between the center lock adapter and the brake rotor. LBS said it just needs tightening.

[Capricorn]

Johan: you right: it was the 6 bolt to center lock adapter, but more an incompatibility that's only recently come to the fore, between the adapter (Alligator) and the rotor (Avid G3 cleansweep).

 

I'm not stoked the LBS gave me the alligator adapter as it's contingent on the use of a compatible alligator rotor.

THey did however try to swop over to a shimano adapter, but it had play as well, albeit reduced. It's tolerable for the moment. Cant wait to swop over to the DH frame...

[Johan Bornman]

Even with the centrelock nut loose, there should be very little play. Play is eliminated thorugh a tightish fit between either bolts or centrelock and not by the actual tightening of these devices. Should there be too much play, you'll experienced lash, which will worsen and could shear the bolts or damage the splines. Lash in drivetrain or brake components is far more destructive than it appears at first sight.

Get it fixed or upgrade to V-brakes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The latter is said of course just to warm things up a bit this cold morning.

 

[Capricorn]

Johan: did you just say upgrade to V brakes? I havent seen any rider since i can remember using V brakes on a downhill. ever. No offence, but that's just a bit out of left field.

 

But roger your concern on the lash. Means I will have to switch to the shimano rotor. dammit.

[Capricorn]

lol.. i didnt see the last bit till now..

[Capricorn]

just a side note to all those interested: SRAM's 2010 product range will include the G-series of discs with a center-lock option. No more third party 6 bolt ?to center locked clearances issues with G2/G3 rotors.

 

Also seems they are increasing the range of Elixir products. Might be some truth to the rumor they are going to drop the Juicy range at some point.

http://www.sicklines.com/2009/04/28/2009-sea-otter-classic-sram-2010-product-launch/

[louis0852]

Capricorn, what do you mean by rolling.I think mine does the same thing?

[Capricorn]

well, some might cnsider a full 360 degree turn of the wheel as rolling . ?Me, referring to the technical definition of the the movement of any wheel, irrespective of the arc distance of its travel.

 

The rolling is due to a poor fit between the rotor and the 6-bolt to centerlock adapter. At the axis where the spacing is, the movement is maybe 1mm, but at the circumference, it's like a few degrees of rotation. very irritating, but not noticable under braking, at least not yet.

[louis0852]

Oh ok cool I get it now, mine don't do that. Well from your definition it doesnt.