Running 203mm rotor on a Rock Shox SID RL fork

M Velo

Hi,

Is it possible to run a 203mm rotor on a 100mm Rock Shox SID RL fork(15mm Thru-axle) which has a Restriction of 200mm max rotor size?

My current weight is 70kg and I am 6'1.

stubs

SIDs are a lightweight XC fork if you need a 203mm disc to stop you when you only weigh 70kg either there is something wrong with your brakes or you need a burlier fork. Downhill racers use the 203mm disc not so much for power as it does give more potential power but for the ability of the larger disc to lose heat on a long downhill with lots of repeated braking. I have a 29er SID fork with 180mm disc, I weigh considerably more than you and I havent yet run out of power.

rockmonkeysc

If you need a 203 rotor on your xc bike then something is wrong.
Im 90kg and only use a 203 rotor on my dh bike even then it's to dissipate heat better as mentioned above. The speeds achieved in dh races are much higher than you're going to see on an xc bike.
180mm should be enough for anyone.

dusk

To answer the question asked, you should be fine as some brake manufacturers have slightly different rotors sizes like 200/203 and 180/185 which are effectively the same size

M Velo

Well I know that 203 is overkill for XC but I love the the braking power of the 203mm. Well I might just go back to the 180mm or 185mm rotor as I doubt if my XT brakes will disappoint me. But the real question is that will the fork actually flex while braking if I use a 203mm rotor as the max rotor size recommended is 200mm.

rockmonkeysc

I found that even with a 180mm rotor on my old Rebas the fork was flexing and twisting under heavy braking and a SID is no stiffer.

poah

use an avid 200mm HS1 rotor if you want to go big