Biggest rear rotor for Rail?

jgusta

Member
Mar 21, 2021
118
47
USA
Bought new brakes (TRP DH-R EVO) to replace the stock Shimano on Rail 9.7 with 203 ice tech rotors/finned pads. Braking power alright, but roasting the rotor a bit almost anytime above 20mph (a lot). TRP thicker 2.3 rotors so shouldn’t heat up and warp and rub as much, but considering 220 or 223mm rotors front and rear. Anybody know if at least a 220 rotor fits the rear. Local Trek store mechanic said it should but I think Trek website says 203 max out back. I am +200lb rider who likes to ride fast and hit the steeps, so need something a little more than Shimano 203.
 

WilkyWay

Active member
Dec 26, 2019
120
102
Durham UK
220mm goes on the rear fine.
CF72CA02-7EA9-45B1-8DCE-B2FA04C6FC22.jpeg
 

Zorg

Member
May 5, 2021
44
6
I
Thanks.

hard to find. found one at r2-bike
might be an overkill for a rear wheel but this plus the magura mdr-p 220mm should stop an elephant . :)
 

Stihldog

Handheld Power Tool
Subscriber
Jun 10, 2020
2,957
4,180
Coquitlam, BC
I’m a 165lb rider on a Rail9.7. I’ve ordered the mt7’s (front/rear and 220mm rotors). I sometimes pack up to 50lbs of tools/materials (trail building at high elevation) and experience brake fad on long decents or heavy braking. I currently have the Shimano w/203 ice rotors f/r.
Now I’ve read that a lighter rider may not want the 220mm rotor because there may not be enough heat for efficient braking. And does the 4-pad/2-pad system make a difference? Does the thicker Magura rotor(220) dissipate heat too efficiently?

It seems like I have two riding styles for one bike.
 

WilkyWay

Active member
Dec 26, 2019
120
102
Durham UK
@Stihldog I’m 150lb riding weight running MT7’s with 220mm rotors from and rear and have no issues with them at all hot or cold. I changed from Saints with 203mm ice tech rotors and the difference was noticeable immediately.
 

Zorg

Member
May 5, 2021
44
6
I
What about pads manufacturer ? does it matter ? or you guys just buy from the same manufacturer of the breaks ?
 

Smittylube

Member
May 14, 2021
102
62
Santa Cruz
I put these rotors on my 7 front and rear. The stock brakes didn't line up as I like with a similar bracket, so I 'adjusted ' the bracket.
The stock brakes work excellent with these rotors and well worth the time and $.
Very pleased with the results.
 

Stihldog

Handheld Power Tool
Subscriber
Jun 10, 2020
2,957
4,180
Coquitlam, BC
It looks like I won’t get the mt7’s until mid July. Levers, callipers, hose/lines, 220mm rotors, spacers, blue-blood etc. I’m gonna give the 4 pad system a try also and keep the original pads as a backup. Apparently the 4 pad system is supposed to be better with the 220mm rotors. (Less noise, better alignment). Kinda makes sense…I think ?. We will see.
 

Smittylube

Member
May 14, 2021
102
62
Santa Cruz
I really like the stopping power with the 220’s. With the added weight of the bike as well as the big tires, it’s nice to be able to stop as well as it does now. The 200’s work well, but the 220’s eliminate any questions of stopping power With less effort.
 

Smittylube

Member
May 14, 2021
102
62
Santa Cruz
True the stock brakes work well, but a larger rotor requires less effort. Mine is the 7 so it does not have xtr, but still 4 piston.
 
Last edited:

Smittylube

Member
May 14, 2021
102
62
Santa Cruz
I just spun my wife’s 7 up and down the street and there is a very noticeable improvement from the stock size rotor. Very worthwhile improvement IMO.
 

Smittylube

Member
May 14, 2021
102
62
Santa Cruz
True, but the larger rotor requires less effort. For me it helps me ride more relaxed at speed. Stock 7 brakes are 4 piston also.
if I didn’t mention I did 220 both front and rear.
 

Richiefromboston

Active member
Mar 15, 2021
224
116
Boston, Ma. USA
I’m a 165lb rider on a Rail9.7. I’ve ordered the mt7’s (front/rear and 220mm rotors). I sometimes pack up to 50lbs of tools/materials (trail building at high elevation) and experience brake fad on long decents or heavy braking. I currently have the Shimano w/203 ice rotors f/r.
Now I’ve read that a lighter rider may not want the 220mm rotor because there may not be enough heat for efficient braking. And does the 4-pad/2-pad system make a difference? Does the thicker Magura rotor(220) dissipate heat too efficiently?

It seems like I have two riding styles for one bike.
piston SLX vs. 4 Piston XTR are day and night not even close, for whats thats worth to you.
 

MartinD.

Member
Apr 4, 2021
31
22
Halifax, UK
Brake much harder and for less time. The rotors will get hotter during the braking phase but cool down quicker when you're off the brakes. Extended applications of lighter braking don't give a chance for the disc/pads/callipers to cool down.

(A useful tip learned from racing cars)

But, cannot argue with the added bling factor.
 

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