what would you need to adopt Disc's on your Road Ride?

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Colin

by Colin

mattr wrote:
Colin wrote:Pads/disc will rub if it's not set up properly...but so do rim brakes.
TBH, rubbing rim brakes is generally a doddle to fix, 30 seconds with a couple of allen keys and you are done until you next do a major change.
Rubbing discs can be a pain in the arse and take ages to fix involving draining oil, jiggling and lubricating pistons, swearing at things until its done, then popping a wheel out and back in again and you have to start all over again. (dependent on the actual model/brand of brake.)


Sounds like you've only ever used Avid brakes :lol: (I'm mostly kidding, by the way). Once you've properly set up a set of disc brakes, it is, IMO, easier than rim brakes. And rim brakes aren't hard. As parsnip said, you loosen a couple bolts, give the lever a couple squeezes, and then re-tighten the bolts. In my experience they stay drag free pretty much from then on. My Shimano mtb brakes require no more service than my Dura-Ace brakes.
Bleeding them can be a pain at first, but it's honestly not that bad once you've done it a couple times. In the last 2 years, I've bled my XTR brakes once, and that was because they were setup poorly from the shop.

As far as hubs go, I would be very surprised if it's much different than mountain bikes. Front hubs will stay 100mm, some will be normal QR, some will be 15mm thru-axle. 110mm front hubs aren't very popular, I highly doubt it'll catch on for road bikes. It appears that rear hubs will bump up to 135mm, I'm sure some will try and get 130mm disc frames to catch on, but I don't see that happening. There are HUNDREDS of 135mm disc hubs. 142mm rear thru-axle's is a possibility, but I don't see that catching on with road bikes any time soon, but who knows!

by Weenie


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mattr
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by mattr

No, spent several years spannering on all sorts, avid, hope, formula, magura and shimano (off the top of my head) some are better than others. The latest ones are better as the clearances are getting bigger. So they are more tolerant to odd disk thicknesses and run out.
And the older and more abused the brakes, the worse it gets. Slightly over filled, bit of dirt in the piston bore, worn down discs and so on. Especially frustrating with non-serviceable/rebuildable brakes. Hence everything we run today is either latest generation shimano (big clearances) or hope (big clearances and home serviceable) and some bb7s on the wife's cross bike.

DRAGON60
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Location: Victoria,B.C.

by DRAGON60

What do you think a disc package would add weight-wise. I have never used discs on a bike yet but surely they must be considerably heavier than say a Shimano Dura-ace setup. Are discs getting lighter? Will Weight Weenies adopt them if they aren't weight competitive?

Coming from the brakes I used as a kid I still find v-brakes really impressive.

sigismond0
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by sigismond0

The total weight will be higher, but rims will be lighter without the need for braking surfaces. Weight savings at the rim is considerably more valuable than the weight of the stationary caliper or the disc at the hub.

MichaelB
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by MichaelB

I've already gone disc for the road for some time now.

The latest ride is a Volagi Liscio (Gen 2). With a 57cm frame, handbuilt 29er carbon clinchers with CM hubs, Ultegra 6700, SRAM Exogram compact crank, TRP Parabox and 180/160mm discs and Pro Logo saddle, it weighs in at 7.5kg (w/o pedals or bottle cages).

Oh, and the best thing is that I can fit 25C tyres with full proper fenders for winter :mrgreen:

Prior to that I had a Kona Honky Inc and modded an Argon 18 Platinum to fit a CX fork with disc.

So far about 13,500km of road riding with discs.

The next step is to fit different calipers (coz I can), but probably upgrade to Di2 with their hydro discs when they are released later this year.

There are now several big players with road discs, with Pinarello being the latest.

Really looking fwd to seeing what comes out in the next 6 months :mrgreen:

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maddog 2
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by maddog 2

I've heard rumours that BMC are working on a carbon Granfondo disc so we'll see if that's true...

They already make a alu GF disc which is quite nice.

mjduct
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by mjduct

MichaelB wrote:There are now several big players with road discs, with Pinarello being the latest.

Really looking fwd to seeing what comes out in the next 6 months :mrgreen:


do you mind posting a link of the Pinarello, all I can find is their disc cross bike on the website


MarkMcM
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Joined: Fri Mar 26, 2010 4:24 pm

by MarkMcM

thisisatest wrote:With road bikes and their reduced need for absolute braking power, it would be easy for the brake guys to spec a slightly larger master cylinder or smaller caliper pistons to increase throw, and a piston seal that retracts farther.


It has often been claimed that road brakes need less power, but that is dead wrong.

First, you have to get your terms right. Brakes have both stopping Force, and stopping Power. Force is related the deceleration rate. Power is related to the rate of energy absorption/dissapation. It is the stopping Power that can result in brake overheating.

In terms of stopping Force - road tires on pavement have more traction than MTB tires on dirt, so a road brake can generate and use more stopping Force.

Road descents can be longer than MTB descents, with less rolling resistance losses than knobby tires on dirt, so some riders will drag their brakes for long periods of time on road descents. This results in larger lengths and rates of energy absorption on road bikes, and greater potential for overheating. The potential for overheating is why there are so few road disk brakes on the market - manufacturers haven't fully worked out how to address this.

MarkMcM
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by MarkMcM

sigismond0 wrote:The total weight will be higher, but rims will be lighter without the need for braking surfaces. Weight savings at the rim is considerably more valuable than the weight of the stationary caliper or the disc at the hub.


This has been often claimed, but the math doesn't work out. It is true that a disk brake road rim needs a thicker sidewall to account for brake track wear. But this only adds about 40-50 grams of material at most. If you compare dis brake-specific rims to otherwise similar standard rims, you'll find that the weight difference is usually less than this. Compare that to about 100 grams of extra weight for a disc brake (rotor, bolts caliper, special hubs, etc.) and you'll find that the disc brake bike weighs more by a quarter pound or so.

As far as the rotating weight being more important - this is true, but the affect is usually overestimated. Weight at the rim has twice the inertia as weight at the hub, so if the disc brake eliminated 50 grams at the rim but adds 100 grams at the hub, it will have the same total inertia. But inertia only matters when accelerating and decelerating, it has no affect at steady state speeds (including steady state climbing). So, with the disc brakes, you have a bike that accelerates/decelerates the same rate (same inertial), but climbs slower (due to the higher total weight).

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cula_ru
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by cula_ru

I'm in.

Just not much offers on the market now are they?

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cula_ru
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by cula_ru

hey. Moment of Inertia has a square factor on the formula so check your numbers now. ;)

thisisatest
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by thisisatest

I meant power, so I typed power.
In mountain biking, first, you brake much more often. Second, most applications are delicate balancing acts, a little too much rear brake in a corner and the rear tire slides out, managing subtle undulations in the corner itself while looking for anything you can turn into a berm... And the need to slow down as quickly as possible comes up regularly.
Road braking is sometimes about decelerating as quickly as possible, that is somewhat rare unless you're in some monster mountains. And the need for ultra-subtle control is much lower. That is a big reason why so many people think discs on a road bike are pointless (that is not my opinion, my opinion is irrelevant here).
As far as people dragging their brakes all the way down a mountain, that is why thermal mass and ventilation/dissipation are the big issues, not power. Nobody is talking about putting 200mm rotors on road bikes, not 180mm even. 140 on the front is often talked about, except for, in its current guise, its lower heat capacity. So I said road brakes are going to have small, wide discs with internal vent channels and/or the aluminum cores and wavy fins that Shimano has on their Ice Tech Freeze rotors.
So like I said, I meant power.

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eliflap-scalpel
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by eliflap-scalpel

i choose a LTK frame, disc native

not on web site, had a mail exchange with Alisa from LTK in november


wonderful with hydraulic RR1 disc brakes
http://eliflap.it/

by Weenie


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atakaoka
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by atakaoka

probably a wider tire contact.
doesn`t mather how much breaking efficiency improve,if the tire contact area remain the same.
cycling,a great individual sport,were you can't reach anything,whithout group effort.

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