Discs. Is heat still a problem

[dyna-ti]

Not ever having applied the brakes long enough to cause a build up of heat i wouldnt know but i keep seeing the makers adding little advantages to supposedly offset it.
Shimano is including fins on just about every caliper and theres more there than on my graphics card :shock: Hope have their 'floating' rotors to dissipate it.

OK C2's had the reputation of heating up but in the 6 years i ran mine not once did i need to back off the pads. Sure i can see that on the long hills or abroad like the alps is where this problem would have presented itself but not really on XC and never when commuting. and i suppose the early Hopes had their own floating rotor :?
Shimano went the mineral route and claimed that mineral oil didnt heat up the same(tbh i cant remember the reason, was something like that wasnt it :? ) but are still adding these fins to remove the supposed heat build up
Havent really seen Hope address this issue beyond the rotors so is it, with the open system ,really still a problem ?


Or does it all come from the Bloody Americans and Europeans where they get lovely weather
Sorry, not a great deal of point to this thread but ....

 

[brocklanders023]

Re:

Can't say I've ever had a problem even though I tonk along and am a heavy lad. Only issue I've found is 'glazing' the pads after they got a bit hot. They still worked but not as well.

I imagine the real hardcore Enduro or DH gang will notice but I wouldn't worry to much about XC.

 

[jimo746]

Re:

Only ever had overheating issues twice, both in the last year or so, and both on long descents off-road, smoking brake pads hot! :shock:

Personally I think the fins etc are just a marketing gimmick, another model of brake pad to sell, there may be some truth in their claims but I'm dubious as to how effective they are.

Heat can be a problem on any braking system, but for commuting & general xc/trail use I can't see that there's too much need to be concerned about it.
For the more All Mountain/Big mountain/enduro etc and Downhill then it's more of a problem, but still, you've got to be going some to overheat modern brakes.
If anything I'd have thought Hope brakes which use Dot fluid would be less susceptible to heat buildup, as that's what's used in motorsport isn't it?? and I'm sure they see much more brake overhating & fade than most MTB'ers.

In summary... fins/ice-tech whatever is mostly marketing & sales built upon a grain of truth and real data imo. Better to just fit some larger discs

 

[syncrosfan]

DOT fluid is better at dealing with overheating than mineral oil (higher boiling point). The main reason many manufacturers use mineral oil is the fact that it's non corrosive and a lot easier to work with, also mineral oil doesn't soak up water like DOT fluid, so it's less problematic to use in the long run. The finned rotors help dissipate the heat but you will only need that on long downhills, for regular XC duty regular rotors will work just fine.

 

[mattr]

I've managed to over heat a brake once.
It'd not been bled for 3 years, the oil was probably 10% water.
I was doing repeated runs down a steep technical 300m descent, with extended brake dragging, no other way down! Several near vertical drops and lots of tricky bits.

And it was about 30 degrees and bright sunshine, with no breeze.

Since bleeding them, it's never happened again.

 

[jimo746]

Re:

Now I remember, the 2 overheating incidents I had were with the OEM Tektro brakes, mineral oil filled, organic pads, with 180/160 XT Ice-Tech rotors.

Since swapping them for Hope Tech V2's with 203mm discs I've had zero issues!

 

[mattr]

TBH, i reckon the majority of overheating issues (even in the alps) are user related.
1) Poor technique, really, you don't NEED to drag your brakes All. The. Way. Down. The. Hill. I've seen road riders doing it too, dragging their rim brakes down a 20km descent. As they refuse to exceed 40kph. Then they wonder where the smell of burning rubber comes from, and why their brakes don't work properly anymore.
2) Poor maintenance, changing the oil regularly isn't actually a huge chore, less than an hour to do both ends and replace the pads.
3) Completely the wrong gear for the job, XTRs, with small rotors might look cool and save you loads of weight, but you weigh 15 stone, are riding a 6" travel trail bike round the alps, maybe look at something a little better suited to the job.

This last one is more than likely why we even have XTR trail as a groupset, so trail/DH riders can have XTR, but not die.

 

[FluffyChicken]

Re:

Do they use carbon discs yet?


I found to stop traditional rim brakes over heating, a good douse in mud and water really helps.it so much easier with rim brakes to do that ;-)

 

[boxxer]

Ive had Hope E4's (the old 2 part Enduro Ones) fail on me at Fort Bill due to heat build up, fried the seals and I had to run from the deer gate down with almost no braking power... wasnt fun! Prob pilot error rather than anything else though..

 

[scant]

DOT fluid is better at dealing with overheating than mineral oil (higher boiling point). The main reason many manufacturers use mineral oil is the fact that it's non corrosive and a lot easier to work with, also mineral oil doesn't soak up water like DOT fluid, so it's less problematic to use in the long run. The finned rotors help dissipate the heat but you will only need that on long downhills, for regular XC duty regular rotors will work just fine.

yes your reasons are correct, but actually the main reason Shimano choose to use mineral oil over Dot 4 or 5 is that its noticeably cheaper to ship mineral oil for insurnance purposes. when you deal in the quantities Shimano ship worldwide the minor savings make sence.

for the original question. no heat isnt a massive concern for modern disc brakes. hour long descents in the alps with 50odd hairpins worth of braking even on stock XTs wasnt an issue.