Should I use 160 rotors for both front and back?

[sowestport]

Is it overkill to have 160 rotors for both front and back for my gravel bike?

[tigoat]

Don't know what you should do but 160mm rotors are definitely not overkill for a cross bike.

[sowestport]

Don't know what you should do but 160mm rotors are definitely not overkill for a cross bike.

It's not overkill for both front and back?

[tigoat]

It's not overkill for both front and back?

Yes for both front and back. If anything, it also looks nicer with both rotors in the same size. Don't know why they even made a 140mm rotor, as I don't want any of it.

[sowestport]

Yes for both front and back. If anything, it also looks nicer with both rotors in the same size. Don't know why they even made a 140mm rotor, as I don't want any of it.

Thank you, TiGoat. Happy New Year!

[gdw]

What is the combined weight of you and the bike?

[sowestport]

What is the combined weight of you and the bike?

Should be <165lbs.

[PaMtbRider]

Which brakes and rotors? Shimano puts no weight limit on their new R785 hydraulic discs with 140 rotors.

[wallymann]

depends on your riding, but intuitively any multi-wheeled conveyance truly only needs smaller braking capability in the back. that's purely a function of physics and not up for debate.

but some riding pursuits can make equal braking in the rear a good idea.

[Likes2ridefar]

depends on your riding, but intuitively any multi-wheeled conveyance truly only needs smaller braking capability in the back. that's purely a function of physics and not up for debate.

but some riding pursuits can make equal braking in the rear a good idea.

agree, i'd get the smallest available in the rear.

take my motorcycle for example....it has two huge discs in the front and one tiny one in the rear.

[sowestport]

agree, i'd get the smallest available in the rear.

take my motorcycle for example....it has two huge discs in the front and one tiny one in the rear.

Good argument. I guess I should go with convention and use 160 in the front and 140 in the back.

[David Tollefson]

You might think about how you tend to brake and what the terrain is like on which you'll be riding. Lots of long downhills where you tend to drag the rear brake for speed control? Then go with the larger rotor in the rear for heat reasons.

[sowestport]

You might think about how you tend to brake and what the terrain is like on which you'll be riding. Lots of long downhills where you tend to drag the rear brake for speed control? Then go with the larger rotor in the rear for heat reasons.

Damn. Another reason to go back to 160 in the rear. I do have some long, fast downhills that I will use the rear for speed control.

[oldpotatoe]

Damn. Another reason to go back to 160 in the rear. I do have some long, fast downhills that I will use the rear for speed control.

Can't even spell 'disc brake', but is there any downside to a 160mm in the rear?

weight-no, aero-ness-no, too much brake-no. buy one rotor if one wears out-replace front-put front in rear-yes

[sowestport]

Which brakes and rotors? Shimano puts no weight limit on their new R785 hydraulic discs with 140 rotors.

I was thinking about the TRP hy/rd's

[Liv2RideHard]

I run BB7 S Road discs on one of my CX/Gravel bikes and will be running HY/RD's on my race specific CX bike. 160 front and 140 rear on both. No need for a 160 in the rear. Purely aesthetic IMO. Even on my MTB, I run the 160/140 and always have. I haven't haD any issues whatsoever with this setup and that includes riding in the mountains/descending. And I don't descend off mountains very fast on the MTB, especially if the singletrack is real tight. All about how you modulate. Hope this helps.

Guy

[etu]

Lot of thought for 10-20gm?
I have been happy with 160 f/r
Lot of ups and downs where I rude

[GRAVELBIKE]

I just built up a new gravel rig with SRAM CX1 and went with 160/160. Works just fine. My 29er is the only bike where I run different sized rotors (180/160).

[kramnnim]

Don't you need an adapter to use a size other than the default?

[cderalow]

Don't you need an adapter to use a size other than the default?


I was thinking along the same lines.

Go with what the frame/fork are setup for if post mount.

My disc equipped hybrid would require an oddball IS adapter to run 140mm discs in the rear.

[vqdriver]

there's a reason why mtb use a smaller rotor in back. or alternatively, a bigger rotor in front. on steep sections, your weight shifts forward, almost all of it on really steep sections with multiple dropoffs like rock gardens or rooted sections. here, it becomes exceedingly easy to lock up the rear which sucks because you'll either loose all your momentum and tip or loose the back end sideways. either is unpredictable and the opposite of what you want. i've yet to build up my own gravel disc bike so i don't know how any of that translates to fireroads or gravel trails, but i suspect you won't find yourself in those situations. but the theory holds. when you're braking your weight shifts forwards so you use a smaller rotor in back to maintain the ability to modulate. you can probably use 160/160 but my prediction would be that instead of thinking 'wow my back brake feels great' it's going to feel like 'wow my front brake feels weak'

[Likes2ridefar]

I can easily lock up my rear rim brake on carbon wheels. yes they are dura ace but i've done the same with rival and TRP.

a disc brake is WAY more powerful and requires even less effort at the lever. at least all the ones I've used.

[gavingould]

9 months on R785s with zero previous disc experience.
road and cx, clinchers and tubular, rider weight 225lbs
160 front and rear. no problems.

[abalone]

It's not usual to see the same diameter disc brake on the front and rear of motorcycles. I'm sure they've been down this thought process also. In the end, I think most road bikes are going to follow along the same ideology as motorcycles for the reasons people have stated here. I think that eventually we are headed to a most common size for road bikes, and right now it looks like 160mm front and 140mm rear may be that most common size.

[bluesea]

It's not usual to see the same diameter disc brake on the front and rear of motorcycles. I'm sure they've been down this thought process also. In the end, I think most road bikes are going to follow along the same ideology as motorcycles for the reasons people have stated here. I think that eventually we are headed to a most common size for road bikes, and right now it looks like 160mm front and 140mm rear may be that most common size.



Its unusual for most of the motorcycles I tend to pay attention to. Even so I think most of those disc configurations, use a much stronger multi-piston setup in front.

A 160/140 is like running Campy single pivot in the rear. Rear double pivot calipers are a bit over kill.

[abalone]

Its unusual for most of the motorcycles I tend to pay attention to. Even so I think most of those disc configurations, use a much stronger multi-piston setup in front.

A 160/140 is like running Campy single pivot in the rear. Rear double pivot calipers are a bit over kill.


Sorry, what I meant... And stated differently for clarification... Is that it is unusual to see the same diameter discs on the front and rear wheels of motorcycles.

[xjoex]

160mm front and rear. I can't see why not too. I've been running that setup without issues since 2007.

https://lh4.googleusercontent.com/-hcPEfmS5pMg/UuxG4wJgbbI/AAAAAAAAPr0/IY6HtcLorTE/s720/P1310106.jpg
https://lh3.googleusercontent.com/-GAur1lfjr_A/U1w7SIty1NI/AAAAAAAAQqI/yaOw0gO3Ij4/s720/P1000942.jpg

-Joe