Lets talk brakes..

[tufty]

Re: Re:

Re tufty

Im surprised disc rims are heavier since the do no have sidewall.

So was I. I was expecting rim brakes to have heavier rims. That said, I only checked a few sets where there were obvious equivalences between rim / disc brake rims, but they all seemed to be pretty much of a muchness.

Also do weights include brake cables and bolts and for disc the rotor bolts?.

No. I didn't get too anal about it, just wanted a sorta ballpark figure.

 

[02gf74]

Re:

Well thats not fair, disc brakes are weighed completewith hydraulic lines; brake cable and inners are still so will add some weight.

Discs brakes will be heavier but maybe 100-200g in it.

 

[JamesM]

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In all seriousness, discs, even cable, are without a doubt better than rim brakes for mountain biking, simply because the braking surface doesn't get contaminated nearly as easily. When the trails are bone dry then cable discs being no more powerful than rim brakes are no better, but hydrailic discs are still better having more power and better modulation. The increased power and modulation comes from the hydraulics over cables rather than disc over rim, assuming the rims are clean. I reckon discs suffer from heat fade worse than rim brakes!!! Thoughts?

 

[kyle888]

Re: Re:

In all seriousness, discs, even cable, are without a doubt better than rim brakes for mountain biking, simply because the braking surface doesn't get contaminated nearly as easily. When the trails are bone dry then cable discs being no more powerful than rim brakes are no better, but hydrailic discs are still better having more power and better modulation. The increased power and modulation comes from the hydraulics over cables rather than disc over rim, assuming the rims are clean. I reckon discs suffer from heat fade worse than rim brakes!!! Thoughts?

Have you ever actually used a decent set of cable discs like avid bb7's?

No better than v brakes??

I went from xt v's to bb7's and the difference was pretty eye opening!



On the point about brake fade i was thinking about that recently after a mate had brake fade on his hydraulic hayes discs after a decent that wasn't even that long. I don't remember ever getting brake fade with v's.

Kyle

 

[JamesM]

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BB7s and Gusset Chutes. Neither any more powerful than my XT 760 parallel push with servowave levers and kool stop pads, which are mighty. Cable discs generally have higher cable losses because they need alot more outer cable.

Once the rims get contaminated then as I said before the cable disc are better.

 

[kyle888]

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What size discs though?

 

[JamesM]

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180 front 160 rear. I do seem to remember that most of the reviews I read for BB7 saying how powerful they are also mentioned that they were using 200mm discs.

 

[kyle888]

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I assume they'd been bedded in as at first i wasn't that impressed then they got way better.
I run a 203mm front
Far better modulation than some avid elixers I've tried out wheelieing etc

 

[JamesM]

Re: Re:

On the point about brake fade i was thinking about that recently after a mate had brake fade on his hydraulic hayes discs after a decent that wasn't even that long. I don't remember ever getting brake fade with v's.

Kyle

I do worry a bit about all these new roadbikes with 140mm discs. Kinetic energy goes up as the square of speed and brakes turn kinetic energy in to heat. Why do we need 180mm discs to stop our 20-30 ish mph XC MTBs but 140mm is fine for a 40-60 mph road bikes.

 

[JamesM]

Re: Re:

I assume they'd been bedded in as at first i wasn't that impressed then they got way better.
I run a 203mm front
Far better modulation than some avid elixers I've tried out wheelieing etc

I had some elixr 5's (180/180), I wasn't going to mention it but I didn't think they were any better than my XT V's in the dry. The elixrs were pretty grabby, good for doing skids . My Formula Megas could stop a train.