Upgrading rotors to 180mm, tell me about adapters.

Minstadave

Minstadave

Minstadave

Caporegime
Joined
8 Jan 2004
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I changed my brakes today from the stock MT410 Shimanos to a set of TRP Slate Evos I got cheap a year or so ago.

I'd like to change my rear rotor to 180mm from 160mm so I can use 2.2mm rotors I'm meant to with the TRPs.

How do you figure out what size adaptor to use is it simply take the original rotor size and add the extra mm to get the new size? They came with adapters that say +23mm on them which I didn't need when fitting. Will they do the job? Or do I need +20mm post mount adaptors.
 
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Frames and forks will be designed for a particular size of rotor as stock, then you can use adaptors to adjust as you see fit. Moat brands adhere to the original IS and Post Mount standards published by Hayes in 2000, other than Shimano and SRAM.

Shimano adaptors are the right geo, but they don't have the 'inside' clearance for bigger calipers from other brands. SRAM adaptors can have the right internal clearance, but use 200mm vs 203mm rotors when you get into the bigger stoppers.

This is a great resource for working out what all your options are for adjusting the size of whatever the frame/fork were designed around. Hope, Hayes, Avid, TRP and a few others all adhere to the original standards.

Without knowing what frame you are running it is hard to be accurate, but at a guess I would assume yours is a 160mm PM fitment as standard. You would then need a +20mm PM adaptor, which would be the HBML from the Hope chart or the PM20 from TRP.
 
Worth checking to see if they're compatible, I upgraded my front rotors from 160mm to 180mm on my road bike and clearance between the fork and rotor was probably only 1mm so I went back to the 160mm rotors. Not my photo, but the clearance is at the top of the rotor.
ycek1hnrbb681.jpg
 
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I didn't check but got lucky and they do fit, it was tight and needed to sand a tiny bit off the PM adaptor at the rear. Messed shortening the hoses a bit bit got there in the end.
 
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Dunks said:
Nice one. It's not something I ever thought of until I fitted them and realised!
Click to expand...
Yeah I messed up multiple times and learnt a lot.

The post mount adaptor had up and an arrow, mounted it as suggested, couldn't get the rear wheel back on. Switched it round and it was perfect.

Shortened the hose three times on the front, first time forgot the compression nut, second time forgot the bloody plastic cover. Not much slack left on that line!

Back brake still feels slightly more spongey then the right, think there's still some stubborn air in the caliper.
 
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Minstadave said:
Yeah I messed up multiple times and learnt a lot.

The post mount adaptor had up and an arrow, mounted it as suggested, couldn't get the rear wheel back on. Switched it round and it was perfect.

Shortened the hose three times on the front, first time forgot the compression nut, second time forgot the bloody plastic cover. Not much slack left on that line!

Back brake still feels slightly more spongey then the right, think there's still some stubborn air in the caliper.
Click to expand...

Hydraulic can be a bit of pain like that. My front hydraulic hose is a bit long, but I'm hesitant to shorten it as I'll end up messing it up, having it too short then having to get new hose and re-do the shifter connection as well as the brake.
 
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