Anybody using a 180 mm disc in back for XC?

[asylum_inc]

Guys - I am going to be doing a disc brake conversion to my 5500 over the winter.  I have ordered a longer travel fork (manitou minute:3), looking for wheels now, and have decided on avid bb7s. Now I need to make the rotor size decision. I am going to get a 180mm rotor for the fork but what about the back?  Are the 'diy' caliper mounts strong enough for larger discs?  I am around 240lbs now - on my way down  I do not want to make a mistake when I do the discs and regret it. Thanks in advance for your help.

[willem]

The giant rotors will save wear and tear on the pads. It will be a little harder to modulate and keep from skidding the rear wheel on loose stuff.

Great plan, though.

[asylum_inc]

So, A 180 (what about a 203 ) on the front and a 160 in the back will be ok for my weight?  If it comes down to modulation I would be able to change that with the 'modulation' feature on the brake lever?  Thanks

[shovelon]

I use a 180mm bb7 on the front of my Oz. It does not heat up and squeal much, and is very strong.

I personally would perfer the 160 on the back because it would be too strong and lock up. Avid speed dial levers are so good because you can change the leverage on the fly. What I did is minimum leverage for the 180 disk with EBC green(organic) pads, and maximum leverage for the v brake on the rear.

Nice thing about bb7 is that to change rotor, you just get a different caliper bracket.

[asylum_inc]

Would a 160 in back give comprable performance to avid arch rivals with crossmax - ceramic coated (non ust/ non disc) wheels? I don't want to go through the time and expense only to be underwhelmed by my new brakes.

[jeffhop]

im currently running a 170mm rear disc on mine without problems, its a bit overkill though as its eay to lock up but it can be done.

[asylum_inc]

im currently running a 170mm rear disc on mine without problems, its a bit overkill though as its eay to lock up but it can be done.

A 170? Now I am confused - I thought it was 160, 180, and 203?

[andy_bro]

I would go with a 160 out back.  The rear locks up pretty easily still.  I was thinking about going to a 180 or 203 up front but be sure to check to see if your fork can handle it.  I was warned by the bike shop of people putting the 203mm on their forks and actually breaking the forks.

[JPSeuropa]

I have a 180 on mine and it is fine. If you really get your weight back, it is great on a steep decent. I don't have any modulation issues and it is nice to be able to one finger brake.

[asylum_inc]

Thanks for the input guys - I ordered a 180 for the front and a 160 for the rear.  I will post pics and let everyone know how it works out...

[jeffhop]

ive got hope xc4`s, they come in 150 front and 130 rear, hope make a +20mm adaptor to take it to 170 front and 150 rear, ive been naughty and used a +40mm adaptor on the back. im thinking of going back to 150 rear as its just as easy to lock up as the 170 but i thought id experiment.

[asylum_inc]

OK - now it makes sense. I thought all of the disc brake sizes were standardized.  3 different sizes made sense to me  I can't wait for the brakes and the rest of my bike loot to show up so I can get working on it.

[wylyman]

Did you find an adapter, or make one yourself?

[asylum_inc]

Did you find an adapter, or make one yourself?

It is a homemade adapter made by somebody else - i will post pics in a new thread when the short travel/ vbrake to long travel/ disc project is further along.