Let's talk rotors

Discuss light weight issues concerning road bikes & parts.
jih
Posts: 314
Joined: Fri Jan 29, 2016 12:54 pm

by jih

Sounds then like smaller or larger rotors come down to larger being a little heavier, some people liking the look of smaller rotors better, possible small change in aero drag, and possible small influence on side winds.

Or, not that critical and just ride what you like :-)

MichaelB
Posts: 749
Joined: Tue Apr 22, 2008 4:31 am

by MichaelB

jih wrote:
Tue Mar 19, 2019 4:33 pm
Sounds then like smaller or larger rotors come down to larger being a little heavier, some people liking the look of smaller rotors better, possible infitessimally small change in aero drag, and possible minute influence on side winds.

Or, not that critical and just ride what you like :-)
Fixed it for you.

And agree with the last line !!

by Weenie


icantaffordcycling
Posts: 1047
Joined: Wed Jan 09, 2019 5:03 am

by icantaffordcycling

50kg 160mm on front and rear because it looks better and because I love to climb but suck at descending. 160mm gives me the mental confidence in my braking.

benzebub
Posts: 360
Joined: Thu May 07, 2015 1:24 pm

by benzebub

quick question: is there a difference in performance between a "dedicated" 160mm caliper and a 140mm caliper + adapter?
But I could be wrong

spdntrxi
Posts: 3825
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

benzebub wrote:
Sat Mar 23, 2019 10:14 pm
quick question: is there a difference in performance between a "dedicated" 160mm caliper and a 140mm caliper + adapter?
in the case of shimano the caliper is the same.. only the adapter is added or (flipped) .. I doubt you could tell the difference.
2019 BMC TM01 Road UCI config 7.36kg

TobinHatesYou
Posts: 6088
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

benzebub wrote:
Sat Mar 23, 2019 10:14 pm
quick question: is there a difference in performance between a "dedicated" 160mm caliper and a 140mm caliper + adapter?
Something like a Hope RX4 effectively has the adapter plates built into the caliper body, so they can only be used with 160mm rotors.

There's also weird front fork configurations like on the BMC Teammachine where the adapter plate isn't used at all and the front caliper is then bolted through the fork like a rear caliper would be. In essence the front caliper is mounted in a "rear 140mm" configuration even though it is being used with a 160mm rotor.

ooo
Posts: 936
Joined: Sat May 21, 2016 12:59 pm

by ooo

BR-UR300 - dedicated 160mm shimano caliper

Image

Image

Image
'

TobinHatesYou
Posts: 6088
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

And here's a photo of a non-standard front 160mm configuration using a bare Shimano caliper without the front plate in either orientation...effectively a "rear 140mm" configuration.

Image

spdntrxi
Posts: 3825
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

TobinHatesYou wrote:
Sun Mar 24, 2019 12:29 am
benzebub wrote:
Sat Mar 23, 2019 10:14 pm
quick question: is there a difference in performance between a "dedicated" 160mm caliper and a 140mm caliper + adapter?
Something like a Hope RX4 effectively has the adapter plates built into the caliper body, so they can only be used with 160mm rotors.

There's also weird front fork configurations like on the BMC Teammachine where the adapter plate isn't used at all and the front caliper is then bolted through the fork like a rear caliper would be. In essence the front caliper is mounted in a "rear 140mm" configuration even though it is being used with a 160mm rotor.
Same with my TimeMachine Road... bummer because I had to order more fixing bolts because when using the adaptors you get 2 shorties.
2019 BMC TM01 Road UCI config 7.36kg

kafreeman
Posts: 138
Joined: Thu Jul 23, 2015 8:46 pm

by kafreeman

It's the same caliper located another 10mm up. The adapter moves the caliper up the fork, where a post mount adapter moves the rotor out from the fork.

Compatibility charts specify frame rotor size designed for vs what is being used and calls out the adapter.



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Yeti
Posts: 2
Joined: Sun Jan 20, 2019 5:08 pm

by Yeti

So what is the general consensus on "the best" rotor to use with Shimano hydraulics? The Dura Ace RT900 or the XTR MT900? Also, at 155 lbs do I really need a 160mm rotor on the front. I know how to brake and don't drag my brakes on extended downhills. Overkill with 160mm?

jfranci3
Posts: 991
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

Aside from weight, only downside with 160mm is if you jump on the front brake too quickly you have a bit more leverage to make a mistake. If you're too high, you'll go over the bars or you might lock too easiliy. The 160 will have ~10% more leverage than 140mm which is only an realistic issue when you first grab the brake hard. I'd go 160/140 unless you've got 140s laying around, tend to startle long or aggressively in emergency brakes (be honest with yourself), or sit high and forward.
140 fr is still good for a heavy person as the pad comes up to temp quicker. If you overheat the pad, it's not a big expense to up the rotor or pad. Unless you waaayyyy overdo it, the pad won't loose all braking when you overheat it. It will smoke (it's actually on fire) and should finish the day as it dusts away.

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Noctiluxx
Posts: 1114
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Location: Southern California

by Noctiluxx

Has anyone used the Hope Floating disk rotors on their Ultegra brakes?
2018 Bianchi Oltre XR4, (Celeste Matt)
2018 De Rosa SK Pininfarina (Blu)
2019 Trek Madone SLR (Rage Red)
2019 Giant TCR Advanced SL (Chameleon Blue)
2019 Cervelo R5 Disk (Team Sunweb)
2019 Giant Revolt Advanced 0

dricked
Posts: 190
Joined: Tue Jan 09, 2018 1:57 pm

by dricked

I’ve been wondering the same. Might help with brake rub being full floating.

by Weenie


TheRich
Posts: 642
Joined: Tue Jan 01, 2019 1:36 am

by TheRich

Yeti wrote:
Thu Apr 04, 2019 6:03 pm
So what is the general consensus on "the best" rotor to use with Shimano hydraulics? The Dura Ace RT900 or the XTR MT900? Also, at 155 lbs do I really need a 160mm rotor on the front. I know how to brake and don't drag my brakes on extended downhills. Overkill with 160mm?
They're all so good after the Freeza rotors came out that it's almost just a question of asthetics.
jfranci3 wrote:
Thu Apr 04, 2019 6:16 pm
Aside from weight, only downside with 160mm is if you jump on the front brake too quickly you have a bit more leverage to make a mistake. If you're too high, you'll go over the bars or you might lock too easiliy. The 160 will have ~10% more leverage than 140mm which is only an realistic issue when you first grab the brake hard. I'd go 160/140 unless you've got 140s laying around, tend to startle long or aggressively in emergency brakes (be honest with yourself), or sit high and forward.
140 fr is still good for a heavy person as the pad comes up to temp quicker. If you overheat the pad, it's not a big expense to up the rotor or pad. Unless you waaayyyy overdo it, the pad won't loose all braking when you overheat it. It will smoke (it's actually on fire) and should finish the day as it dusts away.
Eh, you can do that with rim brakes too, except there's no reason to grab hydraulics that hard.

Using a bigger front rotor is, among other things, a way to generate more power with the front using similar effort at the lever.

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