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disc/rotor performance differences

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Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

disc/rotor performance differences

Old 02-26-19, 12:57 PM
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disc/rotor performance differences

Has anyone here noticed a difference in performance of one disc being far superior to others they've used?

Currently I'm using Shimano SM-RT99 XTR/SAINT Freeza discs, but wonder if I would notice a difference in braking if I used Dura-Ace SM-RT900 Rotors or XT RT81 rotors.
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Old 02-26-19, 01:33 PM
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In terms of braking, I can't say that I've noticed a difference between any of the IceTech rotors that I've used (99s being the highest). In the good thing/bad thing category, I will say that a high spot on my 99s provides audible confirmation that they cool pretty quickly - the high spot will kiss the pads for 5-10 sec after hard braking before going away. I really should give it a love tap or two with the disc tool, but haven't gotten around to it yet. In any event, I think that's the main difference - cooling.
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Old 02-26-19, 01:47 PM
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Originally Posted by WhyFi
In terms of braking, I can't say that I've noticed a difference between any of the IceTech rotors that I've used (99s being the highest). In the good thing/bad thing category, I will say that a high spot on my 99s provides audible confirmation that they cool pretty quickly - the high spot will kiss the pads for 5-10 sec after hard braking before going away. I really should give it a love tap or two with the disc tool, but haven't gotten around to it yet. In any event, I think that's the main difference - cooling.
This confirms what I suspected. For most of the road riding I do, excessive heat isn't an issue.

I'll probably keep the SM-RT99 discs on the OEM wheelset for gravel riding, and buy some XT RT81 discs for the new wheelset. The gravel race I'm planning on doing( AZ Gravel Rides ? Chino Grinder | May 4, 2019 ) will probably require more extended braking than the roads I usually ride.
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Old 06-18-19, 09:50 PM
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Gotta love the search function on here...

Just to add my $0.05, I just replaced the front rotor on my road bike. I upped from the OEM 140mm rotor to a 160mm. I was all set to install the SM-RT800 but when I went to my LBS they sold me the SM-RT81. After doing a bit of bike maintenance, the SM-RT81 is installed and working just fine. At least for the short jaunt in the parking lot around my house.

I'm not sure of the performance difference between the RT800 and the RT81. I'm sure there is weight differences in there somewhere.
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Old 06-19-19, 08:15 AM
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I have RT-81s on my road wheels and they do seem to work a little better than the Tektro rotors that are on my stock wheels that I use on gravel. I'm putting a set of RT-86s on the stock wheels, but mainly because the XT rotors are thicker, so there's always an adjustment period when I swap wheels, and that bugs me, so I'll keep the same rotors across all my wheels to keep it easy. But I also won't argue with better performance and cooling with the extended braking I do off road.
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Old 06-19-19, 08:37 AM
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I was just surprised when my LBS handed me the RT81 rotor instead of the RT800. I figured for a road bike I'd be given a rode rotor. So long as the RT81 gives me good stopping power, and doesn't weigh a lot more, I guess I'm good to go.
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Old 06-19-19, 08:41 AM
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Originally Posted by noodle soup
Has anyone here noticed a difference in performance of one disc being far superior to others they've used?

Currently I'm using Shimano SM-RT99 XTR/SAINT Freeza discs, but wonder if I would notice a difference in braking if I used Dura-Ace SM-RT900 Rotors or XT RT81 rotors.
FTR, I've not noticed any difference in braking performance between Shimano SM-RT99 XTR/SAINT Freeza discs and XT RT81 discs, but I haven't done any long descents that required long periods of heavy braking.
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Old 06-19-19, 11:13 AM
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Originally Posted by noodle soup
FTR, I've not noticed any difference in braking performance between Shimano SM-RT99 XTR/SAINT Freeza discs and XT RT81 discs, but I haven't done any long descents that required long periods of heavy braking.
I'll be putting the RT81s through a good test this weekend, 120 mile ride with over 17k ft of elevation. So far they've been great, so I don't expect any surprises, but I haven't done more than 3k ft with them yet.
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Old 06-19-19, 03:01 PM
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I'm running the Dura-Ace Ice tech centerlock ones 140mm front and back. Just completed a 120 mi ride with 10k feet of climbing (and multiple -20% hills into a stop-sign) and it worked extremely well, no squealing, no deathgrip, etc. However, I bought them because they simply look a heck of a lot better than the 105 rotors...
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Old 06-19-19, 03:02 PM
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Originally Posted by Rides4Beer
I'll be putting the RT81s through a good test this weekend, 120 mile ride with over 17k ft of elevation. So far they've been great, so I don't expect any surprises, but I haven't done more than 3k ft with them yet.
Wheeeerereere is this ride you speak of??
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Old 06-20-19, 07:25 AM
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Originally Posted by firebird854
Wheeeerereere is this ride you speak of??
Upstate SC/SW NC. Someone took all of the big climbs in the area and made them into a single ride.

(thought it was over 17k ft, turns out it's only 16.5k, I feel much better now!! )

https://ridewithgps.com/routes/30242597
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Old 06-20-19, 08:48 AM
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Originally Posted by Rides4Beer
I'll be putting the RT81s through a good test this weekend, 120 mile ride with over 17k ft of elevation. So far they've been great, so I don't expect any surprises, but I haven't done more than 3k ft with them yet.
I'll be putting the 160mm RT81 (front only) through the paces this weekend too. 132k with 8,800' elevation gain. I've done one local ride though and so far, so good.
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Old 06-20-19, 11:01 AM
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Originally Posted by Rides4Beer
Upstate SC/SW NC. Someone took all of the big climbs in the area and made them into a single ride.

(thought it was over 17k ft, turns out it's only 16.5k, I feel much better now!! )

https://ridewithgps.com/routes/30242597
If I was even remotely close by... have fun!
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Old 06-20-19, 11:34 AM
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Originally Posted by NoWhammies
I'll be putting the 160mm RT81 (front only) through the paces this weekend too. 132k with 8,800' elevation gain. I've done one local ride though and so far, so good.
Mine are 160 as well, front and rear, which is nice being 185lbs, the brakes are def confidence inspiring.

Originally Posted by firebird854
If I was even remotely close by... have fun!
Gonna dust off the old gopro and hopefully get some good footage.
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Old 06-20-19, 03:55 PM
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Originally Posted by Rides4Beer
Upstate SC/SW NC. Someone took all of the big climbs in the area and made them into a single ride.

(thought it was over 17k ft, turns out it's only 16.5k, I feel much better now!! )

https://ridewithgps.com/routes/30242597
Good lord! Pretty sure I can't squeeze 17k out of 120 miles anywhere around here unless doing repeats...and I look at several 10k ft. peaks out my front window! And I thought SC was flat...
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Old 06-23-19, 09:13 PM
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Originally Posted by ridethetown
Good lord! Pretty sure I can't squeeze 17k out of 120 miles anywhere around here unless doing repeats...and I look at several 10k ft. peaks out my front window! And I thought SC was flat...
It's funny, most of the state is pretty flat, it's actually ranked the 4th flattest state lol But the upstate and Western NC have some great climbs.

First off, I will say that there is absolutely no way I would do this ride on rim brakes, holy cow. Not knowing the roads, and having other riders in front of me, I was on the brakes a lot, and on the really tight switchbacks you had no choice but to scrub off almost all of your speed to make the turn.

I figure with me, the bike, and water/supplies, I was hauling about 215lbs up and down the mountains. Had no problems at all with the RT81 rotors, they were fantastic. On some of the really hard braking efforts, the rotors would heat up enough to expand and when I'd let go of the levers they would rub for a few rotations, but they cooled down pretty quick and were quiet again.
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