UCI approve disc & looking at weight limit

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Benno
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by Benno

Giant seems to think the demands from road braking are less than mtb. My Defy came with 140mm rotors front and back.

MichaelB
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by MichaelB

LionelB wrote:
.....
I have a bike with shimano hydro road discs (I use this bike mostly on mixed road/dirt rides). I would not switch my main road bikes to discs. Overall they work OK. They are no game changer though.

....


Nice bike.

I'm sorry, but the comparison of how the discs perform on mixed road/dirt rides when it is a CX bike compared to the road bike on road rides is not really a direct comparison. Meh, it's your opinion though.

I'm a fan of road disc, and think it's better in the dry and wet, whether it's pouring or drizzling. And that's with RS685 levers and Zee calipers on a road bike, with 180f/140r discs.

140 discs on the front are crazy

It will be interesting to see them in action in a race, and what the feedback is from the pro's.

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Cheetahmk7
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by Cheetahmk7

maddog 2 wrote:
Cheetahmk7 wrote: Missing end caps in handlebars can seem pretty innocuous too and yet they have killed people.


the end caps killed someone?


Absolutely, missing end caps have killed people.

pushstart
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by pushstart

I have been more than happy with 160/140 setup, but I am not a pro and not descending the alps -- and not using hydro fluid. I think good 160 rotors (I use Avid HSX) provide plenty of stopping power. Just need to be sure to dissipate the heat for long descents, which has had interesting innovation recently with the sandwiched rotors, caliper fins etc. I am sure we will be seeing more of that. 140 front with my current mechanical setup would likely be too small, but 200mm rotors would be pretty extreme. I am guessing they will adopt 160/140 or 160/160 in the peloton, but will be interesting to see later this summer.

centhar
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by centhar

Benno wrote:Giant seems to think the demands from road braking are less than mtb. My Defy came with 140mm rotors front and back.


Yes, for normal road applications, 140-160mm would be fine. However, pro racing in stages with many 100kph+ descents in a day, I feel anything less than 180mm is risky. A 200mm size disc is more heat and fade resistant. Crazy downhillers use them and pros on descents are more crazier.

But this is all in theory. A front wheel and fork setup will be HEAVY and probably handle like crap. No pro would want it. I'd just stick with the old 622mm "disc". :)

BrianAllan
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by BrianAllan

LeDuke wrote:I'm racing pro/open MTB races in the mountains of the SE US on them. No problems for me training on them on the road, either, going up and down 10km ascents/descents.

But, unlike the author of the BikeRumor article, I know how to ride a bike with disc brakes. That is, don't drag the brakes. Look, I feel bad for the dude, but come on. TRP themselves admitted that the product had serious heat issues, and have revised it since that article was published. Read the comments, particularly towards the bottom.

And, let's not equate that experience with modern, full hydraulic products. He was using a cable-actuated hydraulic adapter on a NAHMBS special. Hot garbage when compared to XTR calipers, hydraulic line, and levers. Had the brakes ever been bled? Probably not.

Also, choose products that match your desired riding style. 200lbs and want to bomb down canyon roads at 55mph in Colorado? Get some IceTech rotors. 116g a piece. No brake fade, no glazing. 145lb XC racer hitting 45mph, max, on dirt roads? You can get away with lighter options.


So, just so we're clear, you train on the road on your MTB? We're talking about equipment being used under speeds roughly 20mph faster than what you're likely to be able to reach. It also sounds like you've never had to deal with neutral wheels in a road race.

Again, you keep talking about MTB'ing, which is totally different scale of forces than what you hit in a mountain road course.

I've run the Ashima rotors (140mm/160mm) for 4 years on my XTR/XC bike, and they're barely adequate at 150lbs. I'm hitting 30-35mph TOPS.

BrianAllan
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by BrianAllan

superdx wrote:It's kind of amusing that people keep trying to use the amputation/cut thing as an argument. There are at least 10 discs already spinning on a normal road bike already and people don't seem to be getting sliced up on those, even there's 1 particularly large spinning disc already, and yeah they're called cranks and cogs.


Have you really never seen someone with puncture marks from a chainring? I can't recall any especially serious injuries from the CR, but I've certainly had friends with "shark bites" from crashes.

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Benno
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by Benno

We can speculate all day long whether road braking needs exceed that of mountain biking but until we start to see some real tests I wouldn't be surprised either way.
I don't have much time on my Defy since I am away right now but I'll report back on my impressions of the 140mm rotors when I get some more riding in on that bike.

eric
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by eric

BrianAllan wrote:Have you really never seen someone with puncture marks from a chainring?


Unlike brake discs, chainrings are actually somewhat sharp.

fogman
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by fogman

UCI approved disc brakes, but did not mandate them, correct? Time will tell whether they are adopted by the pro peloton or not.
It's all downhill from here, except for the uphills.

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Benno
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by Benno

Discs actually are kinda sharp lol. I almost cut the tip of my finger off working on a bike while not paying attention. Probably the largest danger associated with discs.

Cheetahmk7
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by Cheetahmk7

BrianAllan wrote:
superdx wrote:It's kind of amusing that people keep trying to use the amputation/cut thing as an argument. There are at least 10 discs already spinning on a normal road bike already and people don't seem to be getting sliced up on those, even there's 1 particularly large spinning disc already, and yeah they're called cranks and cogs.


Have you really never seen someone with puncture marks from a chainring? I can't recall any especially serious injuries from the CR, but I've certainly had friends with "shark bites" from crashes.


And something to remember is that a bike won't work if you take away the chain ring so we are stuck with that risk. Discs on the other hand present a new and unneeded cutting risk. Time will tell how much of a risk it really is and if it is a risk worth taking.

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LeDuke
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by LeDuke

BrianAllan wrote:
LeDuke wrote:I'm racing pro/open MTB races in the mountains of the SE US on them. No problems for me training on them on the road, either, going up and down 10km ascents/descents.

But, unlike the author of the BikeRumor article, I know how to ride a bike with disc brakes. That is, don't drag the brakes. Look, I feel bad for the dude, but come on. TRP themselves admitted that the product had serious heat issues, and have revised it since that article was published. Read the comments, particularly towards the bottom.

And, let's not equate that experience with modern, full hydraulic products. He was using a cable-actuated hydraulic adapter on a NAHMBS special. Hot garbage when compared to XTR calipers, hydraulic line, and levers. Had the brakes ever been bled? Probably not.

Also, choose products that match your desired riding style. 200lbs and want to bomb down canyon roads at 55mph in Colorado? Get some IceTech rotors. 116g a piece. No brake fade, no glazing. 145lb XC racer hitting 45mph, max, on dirt roads? You can get away with lighter options.


So, just so we're clear, you train on the road on your MTB? We're talking about equipment being used under speeds roughly 20mph faster than what you're likely to be able to reach. It also sounds like you've never had to deal with neutral wheels in a road race.

Again, you keep talking about MTB'ing, which is totally different scale of forces than what you hit in a mountain road course.

I've run the Ashima rotors (140mm/160mm) for 4 years on my XTR/XC bike, and they're barely adequate at 150lbs. I'm hitting 30-35mph TOPS.


CAT1 on the road, dealt with SRAM and Mavic neutral support many times.

I've gone 51mph on my MTB, on the road. Granted, using XTR rotors.

On my race wheels, Ashima are good enough because, like you said, I think the fastest I've gone is 35mph, and rarely at that.

I think that rotors can and will be developed that will be road specific. Strong brakes aren't really needed; modulation and heat resistance will be more important.

eric
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by eric

Benno wrote:Discs actually are kinda sharp lol. I almost cut the tip of my finger off working on a bike while not paying attention. Probably the largest danger associated with discs.


None of the MTB discs I've had have sharp edges.

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Benno
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by Benno

Yep not my finest hour but almost all the discs I own have sharp edges around the spokes. Plus something that thin doesn't have to be super sharp to lop off a digit.


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