HOT: Active* forum members generally gain 5% discount at starbike.com store!
Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Blog NEW Articles FAQ Contact About




Post new topic Reply to topic  [ 47 posts ] 
Go to page Previous  1, 2, 3, 4  Next
Author Message
PostPosted: Tue Jun 04, 2013 9:30 pm 
Offline

Joined: Mon Mar 02, 2009 4:50 am
Posts: 689
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!


Top
 Profile  
 
PostPosted: Tue Jun 04, 2013 10:25 pm 
Offline

Joined: Fri May 25, 2007 6:43 pm
Posts: 2074
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.


Top
 Profile  
 
Posted: Tue Jun 04, 2013 10:25 pm 


Top
  
 
PostPosted: Wed Jun 05, 2013 12:16 am 
Offline

Joined: Mon May 27, 2013 2:29 pm
Posts: 106
Location: Victoria,B.C.
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.


Top
 Profile  
 
PostPosted: Wed Jun 05, 2013 4:35 am 
Offline

Joined: Tue Feb 05, 2013 8:29 pm
Posts: 236
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.


Top
 Profile  
 
PostPosted: Wed Jun 05, 2013 9:25 am 
Offline

Joined: Tue Apr 22, 2008 4:31 am
Posts: 149
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:


Top
 Profile  
 
PostPosted: Wed Jun 05, 2013 1:44 pm 
Offline
User avatar

Joined: Wed Feb 25, 2009 7:58 pm
Posts: 306
Location: Lancaster, UK
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.


Top
 Profile  
 
PostPosted: Wed Jun 05, 2013 1:56 pm 
Offline

Joined: Tue Dec 27, 2011 2:19 pm
Posts: 651
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


Top
 Profile  
 
PostPosted: Wed Jun 05, 2013 2:07 pm 
Offline

Joined: Sun Jul 22, 2012 7:17 pm
Posts: 326
Image

http://www.bikerumor.com/2013/05/22/pinarello-dogma-disc-brake-road-bike-coming-for-2014/


Top
 Profile  
 
PostPosted: Wed Jun 05, 2013 7:38 pm 
Offline

Joined: Fri Mar 26, 2010 4:24 pm
Posts: 91
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.


Top
 Profile  
 
PostPosted: Wed Jun 05, 2013 7:46 pm 
Offline

Joined: Fri Mar 26, 2010 4:24 pm
Posts: 91
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).


Top
 Profile  
 
PostPosted: Thu Jun 06, 2013 3:47 am 
Offline
User avatar

Joined: Thu May 11, 2006 9:00 pm
Posts: 325
Location: Portuguese Trails and Mountains
I'm in.

Just not much offers on the market now are they?


Top
 Profile  
 
PostPosted: Thu Jun 06, 2013 3:51 am 
Offline
User avatar

Joined: Thu May 11, 2006 9:00 pm
Posts: 325
Location: Portuguese Trails and Mountains
hey. Moment of Inertia has a square factor on the formula so check your numbers now. ;)


Top
 Profile  
 
PostPosted: Thu Jun 06, 2013 5:24 am 
Offline
Shop Owner

Joined: Sat Jun 13, 2009 4:02 am
Posts: 1976
Location: NoVA/DC
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.

Sent from my EVO using Tapatalk 4 Beta


Top
 Profile  
 
PostPosted: Thu Jun 06, 2013 12:21 pm 
Offline
User avatar

Joined: Sun May 25, 2008 10:12 pm
Posts: 645
Location: italy
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/


Top
 Profile  
 
Posted: Thu Jun 06, 2013 12:21 pm 


Top
  
 
PostPosted: Thu Jun 06, 2013 12:38 pm 
Offline
User avatar

Joined: Tue Aug 07, 2012 2:29 am
Posts: 48
Location: Ibiuna-SP-Brazil
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.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 47 posts ] 
Go to page Previous  1, 2, 3, 4  Next


Who is online

Users browsing this forum: Baidu [Spider], Stegger, ultimobici, Yahoo [Bot] and 39 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

   Similar Topics   Author   Replies   Views   Last post 
There are no new unread posts for this topic. Attachment(s) Will UCI ever legalize disc's?

[ Go to page: 1 ... 10, 11, 12 ]

in Road

Bregnhoj

178

10232

Fri Dec 12, 2014 2:21 pm

bm0p700f View the latest post

This topic is locked, you cannot edit posts or make further replies. Does anyone ride with their dog?

in Road

USPS

8

684

Tue Jun 03, 2014 6:55 am

Frankie - B View the latest post

There are no new unread posts for this topic. Bianchi Infinito CV Ride Report

in Road

sethjs

5

909

Tue Aug 19, 2014 6:58 am

sethjs View the latest post

There are no new unread posts for this topic. Carbon handlebars. How long would you ride them?

in Road

Juanmoretime

14

1411

Sun Aug 24, 2014 3:25 pm

davidalone View the latest post

There are no new unread posts for this topic. BH a Ultralight mid-term ride report

in Road

willieboy

8

1213

Tue Apr 01, 2014 2:06 am

willieboy View the latest post


It is currently Mon Dec 22, 2014 7:09 am

All times are UTC + 1 hour




Advertising   –  FAQ   –  Contact   –  Convert   –  About

© Weight Weenies 2000-2013
hosted by starbike.com


How to get rid of these ads? Just register!


Powered by phpBB