Is disc rotor size frame-specific?

Discuss light weight issues concerning road bikes & parts.
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Miller
Posts: 1275
Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

I have a road disc frame on the way which is flat mount at both ends. The supplier says 'they normally use front and rear 140mm rotors for this frame".

Does that mean I can only use 140mm rotors?
Are the flat mount fitments on a frame always in the same place or are they positioned according to the disc rotor size, ie there would be different placing for 140 and 160?

morrisond
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Joined: Thu Mar 25, 2004 8:34 pm

by morrisond

It's the same spacing for both - You should have no problems with 160 on the Fork - sometimes there is only enough room in the back for 140 though - if the rear triangle clearance is too little, but the way flat mount is that would be hard to visualize.

What frame is it?

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Miller
Posts: 1275
Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

So the frame fixings are in a standardised location? 160/140 is what I'm aiming for.

Frame is a Gotobike B36 with slightly custom paint, really looking forward to it arriving.

morrisond
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Joined: Thu Mar 25, 2004 8:34 pm

by morrisond

The standard rear flat mount will take either 140 or 160 - 160 just needs the spacer and for the front if you use the same spacer just flip it over for 160.

It's pretty standard - I can't find a Gotobike B36 image but I would be stunned if you can't run 160/140.

norcimmus
Posts: 33
Joined: Fri May 12, 2017 12:19 pm

by norcimmus

Just to tack onto an existing thread about rotor sizes.

I have a Cervelo R3D, the rotors are spec'd at 140mm. Would 160mm rotors be compatible? If so, I'd like to add the Dura Ace RT900s 160mm rotors to my next set of wheel upgrade.

fasdflkjweorinjs
Posts: 25
Joined: Sun Mar 23, 2014 6:25 am

by fasdflkjweorinjs

Miller wrote:So the frame fixings are in a standardised location? 160/140 is what I'm aiming for.

Frame is a Gotobike B36 with slightly custom paint, really looking forward to it arriving.



Hey Gotobike B36 buddy. Mine is being built up right now as we speak. I have 160 mm rotors for front and back. To mount your calipers, you'll need flat-mount-to-flat-mount adapters for front and rear. In fact, if you use 140mm rotors on the front, you'll need one regardless.

For the front:
https://www.trpbrakes.com/category.php? ... &catid=188

For the rear:
https://www.trpbrakes.com/category.php? ... &catid=188

As well, I can tell you that Gotobike doesn't ship mounting bolts. You'll need to buy them for the front and back. I am using 16mm M5 - 0.80 Allen Head Socket Cap Screw Stainless Steel on the front and on the rear I have two different length bolts:
30 mm
25 mm
both are M5 - 0.80 Allen Head Socket Cap Screw Stainless Steel

Make sure you buy some M5 washers as well.

What color did you get it painted? Mine is matte pantone red.

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Miller
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Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

Great info, thank you!

My B36 is in transit to me as we speak so God knows when it will arrive, lol. After an import duty demand I expect. Mine will be blue and red but slightly custom graphics. I will post it on here in due course most likely. I hope you do too, matte red sounds great.

joejack951
Posts: 364
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

norcimmus wrote:Just to tack onto an existing thread about rotor sizes.

I have a Cervelo R3D, the rotors are spec'd at 140mm. Would 160mm rotors be compatible? If so, I'd like to add the Dura Ace RT900s 160mm rotors to my next set of wheel upgrade.


It appears to be no problem with the BR-RS805 calipers with which the internet tells me the R3D came equipped. See pages 46-51: http://si.shimano.com/pdfs/dm/DM-BR0008-08-ENG.pdf

You just need to flip the adapter over for the front and buy a spacer for the rear, assuming that your frame and/or fork do not interfere with the larger rotors.

myee111
Posts: 1
Joined: Mon Jan 26, 2015 12:30 pm

by myee111

Miller wrote:Great info, thank you!

My B36 is in transit to me as we speak so God knows when it will arrive, lol. After an import duty demand I expect. Mine will be blue and red but slightly custom graphics. I will post it on here in due course most likely. I hope you do too, matte red sounds great.

I went for a 10 km ride this evening in some crazy wind without glasses. Bad idea. First impressions: 28mm tires at 80psi is wickedddddd. My last bike was a velobuilb r16 which has a teeth chatteringly rough ride. The b36 is positively plush in comparison.

For a comparable reach, toe rub has been eliminated!

My build is with trp spyres and 6070 with the new battery and Bluetooth transmitter. I've upgraded the fw with my iPhone etube app but I haven't figured out how to activate syncro shift yet.

Total weight without pedals is just over 8kg so it's not light by any means. I'm just ecstatic about the ride quality.

My orange seal tubeless kit and schwalbe pro ones arrive later this week. Can't wait!


Sent from my iPhone using Tapatalk

lwk
Posts: 74
Joined: Sun Apr 24, 2016 11:02 am

by lwk

This thread needs some pics :beerchug:

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