Rotor size

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  • Rotor size
  • Netdonkey
    Member

    What are the benefits and drawbacks of bigger rotors. I get that the big ones dissipate heat quicker but are there any negatives. I am currently running a 180 front and 160 rear on a 575. And I am wondering what I get for running a 203 front 180 rear.

    Ta

    Premier Icon simon1975
    Subscriber

    are there any negatives

    Weight would be the main one!

    jamiep
    Member

    Ive 203F 180R, but I lack gnarr and am only 60kg and so dont actually need that much stopping power, having to be careful to only gently caress the front brake

    Premier Icon wwaswas
    Subscriber

    big ones weigh a lot more and, I guess, are slighty more prone to damage and thus running out of true. All the extra mounting gubbins for the calipers probably adds up too.

    The rotors are rotating mass too so it’s ‘badder’ to have more…

    pixelmix
    Member

    Price (sometimes)

    Bigger rotors – more power, but less modulation

    They weigh exponentialy more, tiny 140mm rotors can get away with 3 or 4 arms holding the disk to the hub, 203mm+ rotors often have over double that, 8, 10 or more, and IME are often thicker too.

    I run 160/140mm on my XC singlespeed, and 203/185 on my big bike. At 95kg I really should put bigger rotrs on the singlespeed, in the dry I reckon V’s might be more powerfull, I actualy gave myself a shock getting on the road bike and pulling the brakes!

    Netdonkey
    Member

    Arrgh the age old preference thing. at 75kg and not riding massive stuff all the time it sounds like sticking with 180 160 is the way forward

    Cheers

    cynic-al
    Member

    Yup it the added weight makes **** all difference to 99% of riders but they want to believe that they’re so fast it does.

    messiah
    Member

    25g or so per extra 20mm for the disk, and roughly the same for the mounting kit – so 50g per wheel per extra 20mm.

    If your brakes are not feeling short of power and your not cooking them all the time on scary alpine descents I doubt you need bigger rotors.

    205’s are very prone to rock strikes so if you can get away with smaller I would.

    Question I’ve been wondering recently is wether to go for a lightweight brake package with a big disk, or go for a more powerful brake with a smaller disk -the brake systems would work out at similar weights and it would be interesting to find out if there are issues with either option.

    EG

    Hope X2 with 203 vs Hope M4 with 160

    Or

    Avid Elixir with 203 vs Avid Code (2011) with 160.

    Interesting experiment for a mag to do I think – I think I’ll make this question a thread of it’s own…

    I think smaller discs are likely to perform better at low temperatures or in wet conditions when your riding is less gnarr as they’ll warm up quicker and thus stay at optimum temperature longer – which will also result in less squeal. I’d thus only go to bigger discs if suffering brake fade with smaller ones (not had it properly on the bike, had it once in the car and it wasn’t much fun!)

    Placing calipers directly in the airflow and adding cooling fins would be a good thing on all brakes! Would have negligible cost or weight implications too.

    xiphon
    Member

    rather have more stopping power available than not… 203mm each end here.

    speckledbob
    Member

    i’ve got a 203mm on the front. A 180 would have been good enough easily.

    Wasn’t someone saying the other day that Peaty uses 140’s?

    Stuey01
    Member

    Wasn’t someone saying the other day that Peaty uses 140’s?

    He used them on his World Champs winning bike, small brakes was one of a load of weight saving measures they employed so he could eke out some extra speed on the very pedally course. I don’t think he uses them as a matter of course.

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