I’m working on a lightweight build (One One Lurcher carbon 29er with rigid carbon forks) and am considering what disk brakes to fit. While I’m trying to convince myself that lightness is my primary concern, I don’t really want anything that is going to need much fettling/maintenance (or is super expensive).

Shimano XT is usually my default choice as in my experience they are fit and forget. However I’ve never really built up a bike before where weight has been the primary concern, and numerous sources suggest Shimano is not the lightest. What else should I be considering as an alternative? I’m wondering if the weight saving is worth the extra hassle?! You can get a pair of XT’s with rotors for ~£150, so don’t really want to go above £250 for the pair unless it is really worth it.

I also have some Avid Elixir 5’s, which came spec’ed on another bike. These have been faultless (despite their reputation), and I think are supposed to be lighter than XT, but availability appears to be limited…..

I’d go Formula R1 myself- it’s a discontinued model so can be had for good money.

Formula brakes come with really light rotors….

…that are too thin and always end up wavy

XTR? M985s can be had for £210 from Merlin for a complete set. Alu clamp bolts, ti caliper and rotor bolts (or alu rotor bolts if you’re feeling brave), Quaxar rotors.

Or apply the same mods to XT brakes, probably end up lighter than XTR.

wiggles – Member

Formula brakes come with really light rotors….

…that are too thin and always end up wavy

Yeah, they are shit 🙂 But other rotors are available. Formula still make their “oro” rotor which is still a sensible weight and doesn’t have all that bullshit (it used to be the standard fitment til they discovered nobody bought it), or you could stick on ashimas or whatever else.

Formula brakes come with really light rotors….

…that are too thin and always end up wavy

Interesting. Thats exactly the sort of thing I want to avoid. Would rather put up with the extra weight.

So how much weight do we think XTR would save over XT?

XTR with alligator rotors for me – seems pretty light..

XT vs XTR trail below – more to be saved with the newer non-trail XTRs

I went with these

http://www.merlincycles.com/formula-rx-disc-brakes-front-rear-set-53114.html

Not quite as light as the R1 but still a good weight, amazing price

I have had no issues at all with the rotors – they’ve been fantastic so far

EDIT – weight on merlin is including rotors, think they are around 240/250g an end without rotors

I’ll just leave this here 😉

It’ll be a bit overweight, that, because someone’s put a braided hose on it for some reason (standard Formula hose is kevlar braided).

no doubt the r1 are lighter – but (on Merlin anyway) they are £200 an end vs £150 for front and rear on the RX

Some of the german stores had them for a lot cheaper- mine were bought used for £120 IIRC, they’re a good used buy with the reliability and parts availability.

Sorry, I am banging on a bit 🙂 But they’re good, and light, and pretty uncompromised- strong enough for trailbike use and they’ve had a world cup dh podium. Only weak spot is the ergal bar-mounting bolts which I think are designed to be breakaways in the event of a bad crash, they’re not that strong, and damn expensive.

I went with these

http://www.merlincycles.com/formula-rx-disc-brakes-front-rear-set-53114.html

Not quite as light as the R1 but still a good weight, amazing price

I have had no issues at all with the rotors – they’ve been fantastic so far

EDIT – weight on merlin is including rotors, think they are around 240/250g an end without rotors

I need I.S. mount front and rear. Are adapters easily available?

I have an IS mount on the rear – I can’t remember where I got it to be honest but don’t remember having any trouble getting one

Magura MT series are light, and work well.

actually just checked on Merlin

spec suggests the rear comes as an IS mount – it’s an adapter though not IS specific

Most brakes these days are postmount, so you just need an IS-to-postmount adaptor, which are near-universal (Shimano ones are lighter than most).

It is very nearly a standard standard 🙂 So no doubt Fox or Kirk Pacenti will invent a new one tomorrow.

Northwind – Member
Most brakes these days are postmount, so you just need an IS-to-postmount adaptor, which are near-universal (Shimano ones are lighter than most).

It is very nearly a standard standard So no doubt Fox or Kirk Pacenti will invent a new one

Think we’d all like to see 104mm post mount to allow wider, stiffer brakes. The flex in my Saint callipers is really noticable.

And the best bit is, since the industry’s gone postmount on most frames and forks, you’d need to replace your entire bike to make the “upgrade”

Never speak of this again, if they hear…

Thanks for the suggestions all