You cannot use anything smaller than a 203 Rotor on an Xtracycle FreeRad. In fact if you look as the rear IS mounts you will see that is specifically states "203mm".
The BD is a different matter altogether, as Surly had other ideas on minimum rotor size.
'Newspapers are unable, seemingly, to discriminate between a bicycle accident and the collapse of civilization' : George Bernard Shaw
Sent from Melbourne, Victoria, Australia
2009/12/18 speedub_nate <speedub.nate@...>
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, David Chase <dr2chase@...> wrote:
> To the best of my knowledge, the FreeRadical is made to take a 203mm rotor, using a 160mm brake body. When I installed a FR on a bike with existing 160mm disk brakes, I just added a big rotor, no adapters. I have also installed a pair of 185mm rotors on a Big Dummy, starting with new BB7 brakes, cabled, mountain pull.
Generally (I say "generally" but I don't yet know of an exception), a front IS brake caliper or adapter used on the rear position will require a 20mm smaller rotor. For instance, a Front 160mm Hope caliper or Avid adapter will need a 140mm rotor if installed on the rear tabs.
So I suspect a Front Avid 160mm adapter used on the rear of the Free Radical will mate up with a 185mm rotor instead of a 203.
I'll know for sure soon enough, after UPS drops off my hub and rims.
I have this suspicion the rear 203 will be overkill for my intended uses, unless I need the extra rotor material for heat dissipation if I end up dragging the brake a lot on hills.