- How big are your rotors then?
I run 185 rear and 205 up front with sintered pads. I have no issue with over heating, my pads don’t glaze and they still bed in properly. The weight difference between this and the 165/185 standard option was about 40 grms. I can’t think of any reason not to have big rotors. Then again, my brakes modulate very well, if they were grabby, I guess i wouldn’t want big rotors. Don’t know if it’s size related but my pads last for ages.Posted 9 years agocrazy-legsSubscriber
180F and 160R, never had a problem in the Alps/Pyrenees (or anywhere else for that matter).
XC race bike has 160 F&R, more than enough power and modulation there.
I’ve know a guide in the Alps who rides on 160/140 with no problems. It just depends on how good a rider you are and how good your brake set-up is. In fact for a while he was running V-brakes on a hardtail and he still thrashed all the guests on their 6" travel, 203mm rotored full sussers.Posted 9 years agomildredMember
The size of the rotors has little to do with whether they’ll lock up – that’s more to do with your grabby hand and fine motor control.
I’ve found that with bigger rotors I don’t have to squeeze quite so hard, and they generally have better modulation, but they’re certainly not grabby. There’s such a little difference between weights, and because that weight is around the centre of the wheels, I’d fit as big as you’ve got.
One thing worth mentioning is the brake design/manufacturer. I have a couple of sets of Juicy’s with 185mm rear and they work perfect in the big mountains. However, i have just bought a bike with Hope Moto’s fitted as standard and they’re absolutely crap in comparison to the Juicy’s. Possibly pad compound but I certainly have to pull on the lever hell of a lot harder.
What are your brakes?Posted 9 years agoMilitant_bikerMember
Any bigger and you just lock the wheel.
As Mildred says, if you lock the wheel, you are doing something wrong.
I run 200/203/205?mm Hope M4’s front and rear and they are, by far, the best brakes I’ve used. Changed one set of pads up front (to Reds after 4 months) in nearly 3 years, riding in Alps, Fort Bill, Inners, Wales. Original pads rear. And I drag the brakes like a complete wuss. 🙄
That said, I used to have (g)Hayes with 8in rotors and they were the worst brakes ever. Ate pads on a monthly basis and still didn’t work.Posted 9 years agoalpinMember
i am in the alps and have been riding here twice a week or so over the last year.
203 up front with 160 on back.
no i don’t need more at the back. 80% or so of braking force goes through the front wheel. lay off the brakes. don’t hang on the the rear, better off pumping the brake on long decents, not dragging it.
JPosted 9 years agodave_aberMember
Bleed brakes before you go, you won’t get fade
What Dibbs said. Bleeding has nothing to do with fade. That’s all about heat in the pads, and the compound changing its friction coefficient as the temp rises.
With un-bled brakes you just get a spongy feel as you are compressing the gas (air) in the lines – you can’t compress a liquid, which is why these hyd brakes work in the first place.
What you can get with air in the lines, if it is near to the caliper is the air expanding due to the heat build-up (the high altitude / low outside pressure making this worse). You then get into the realm of the brakes binding due to the residual pressure on the pads once you have let go of the levers (vapour lock). Pads rub, heat up more, brakes fade, you squeeze harder against the bubbles, compress them more, apply little more pressure to the pads, you don’t stop.
Also a good idea to make sure your brakes are bled before you stick the bike in the hold of an aircraft, or you may end up with the low pressure expanding the bubbles in the lines and forcing the fluid out – probably onto your pads.Posted 9 years agojamesMember
"never had anything more than a 160mm … Any bigger and you just lock the wheel"
"I’ve know a guide in the Alps who rides on 160/140 with no problems. It just depends on how good a rider you are and how good your brake set-up is"
… and how heavy you are
Grippier tyres will let you put down more braking force before locking up
Currently got 185/185 on the FS after cooking 185/160mm in the lakes, 160/160 on the HT just because the 140mm doesn’t put any power down.
I ran 203/185mm in the alps just because I could get a Shimano 203mm much cheaper than an avid 185mm. I still managed to cook the rear 185mm once
On the flip side I know a couple of light riders insisting on 8" rotors F&R really struggling to get their pads to bed in, having the pad fall off the rotor. Theres not many places most people ride regularly enough to bed in new pads with excessively sized rotors.
"160 FR and RR on the BLT"Posted 9 years ago
You fitted brakes to a sandwich? I’d like to see thatstuartlangwilsonSubscriber
Old fluid has a lower boiling point than fresh.
Having said that, i think a lot of people bleed brakes far too often.
Never boiled the oros 180 f/r on my heckler, or juicys 203/185 or ones 200/180 and they have all been dragged down big hills.
Old Minis however didn’t seem to cope well with heat.Posted 9 years agoaracerSubscriber
Lots of people who don’t understand how brakes work on this thread
Like those suggesting that you’ll just lock up your wheel with bigger discs? 😆
As others have said, the point of bigger discs is better heat dissipation. Not ridden in the Alps, but done 3000ft descents in Utah where you’re going pretty much straight down with nothing really technical – you need to control your speed though, so end up dragging your brakes at fairly high speed most of the way down. My 160/140 were making all sorts of horrible smells and noises by the bottom of that – they still worked, but had very definitely faded. A lot of fading on bikes is down to the pads outgassing as they heat up. If I was doing that sort of thing all the time I’d definitely go for bigger discs, even given that we were racing and had to drag the weight to the top of the hill first.Posted 9 years agomboySubscriber
203 front, 180 rear on my full sus. 180 front, 160 rear on my hardtail.
Congratulations to all those who ride in the alps on small disc braked bikes, or have done it with V brakes etc. Medals deserved by you all obviously 😉
In seriousness, having now ridden for about 7 weeks in the Alps in total over the last few years, and seen so many people lose so much time riding due to problems with their brakes, I say unless you want to tempt fate, or particularly like having your hands pump up too much cos you’re squeezing the levers so hard, go with a 203mm rotor on the front and at least a 180 on the back for certain. If you’re a heavy guy, it’s worth investigating bigger rotors still. And stay away from the sintered pads in the Alps, these will only help you boil your brake fluid very quickly! One guy I rode with my first time in the Alps had almost his entire holiday ruined because of his brakes. He’d saught advice off people on a mountain bike forum (dunno which one) and they had told him his 165/145 Hope Minis would be fine for riding in France. Still, he made sure they were properly bled and had new pads fitted before going.
Well, each day his brakes had to be re-bled. He’d boil them on every descent, and some descents were so bad he’d have to get off and walk down whilst the rest of us were riding! Personally I think it’s better to be over prepared than under prepared, and I can’t think of anything worse than not being able to ride something because your equipment isn’t up to it (as opposed to the rider, which in my case is all too often, but at least my bikes aren’t stopping me). Especially if you’ve paid a lot of money to be riding abroad!Posted 9 years ago
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