Discs or no discs for pros

Questions about bike hire abroad and everything light bike related. No off-topic chat please

Moderators: robbosmans, Moderator Team

jeffy
Posts: 1325
Joined: Sun Oct 05, 2014 11:51 pm

by jeffy

http://road.cc/content/news/160646-team ... first-time

Bernie Eisel's Pinarello Dogma F8 Disk with Shimano disc brakes @ Eneco Tour

Image
Last edited by jeffy on Wed Aug 12, 2015 10:26 pm, edited 1 time in total.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
Calnago
In Memoriam
Posts: 8612
Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

So... 28 spokes 2x. Hmmm, even though I'm not a fan of disc brakes on the highest end road bikes, the added strength they have to add to the rim along with more spokes, and no radial lacing, can only serve to make a stronger wheel for us big guys so I would guess the front end handling might be more stable when in turns that might be a little sketchy on super light wheels, regardless of whether you need to brake or not.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

User avatar
Calnago
In Memoriam
Posts: 8612
Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

pushstart wrote:...I would take my disc brakes any day over the carbon braking surface of my previous bike/wheels. Heck, I would take them over my alloy rims too. But obviously for success in the peloton, there need to be some tech improvement and tighter standardization. I am quite excited for those changes to trickle down to the rest of us too. The idea of using little rubber pads pressed against the rim to slow a spinning wheel is a little humorously crude compared to calipers and rotors.

It doesn't seem crude to me given that the major issues to overcome with discs are 1) heat from braking at downhill road speeds on relatively small diameter rotors; 2) the force being transferred all the way from the hubs through the spokes to the rim. There's a whole lot of stress being applied in that process simply because of where the braking initiates (close to the hub vs the rim) that is not there when the braking force is being applied at the rim. Hence, you cannot lace radially with discs. You generally need more spokes. And you need to make sure the rim bed is strong enough to keep the spokes from ripping out from the force.
The larger diameter the rotor the better when it comes to braking. But weight is a huge issue in making larger rotors, as well as the negative aerodynamic consequences. Current braking systems at the rim are in essence using a huge rotor (the size of the wheel actually) to be able to apply the braking force as close to where you need it, where the rubber meets the road.

I think the ultimate solution for high end road bikes is to come up with a rim material that dissipates heat better than carbon. Braking with some of the newer carbon rims and proper pads is actually getting to be not bad, or at least manageable, but heat buildup is always an issue with carbon rims. And road riders will never have to contend with the mud and dirt and grime that mountain bikers do making disc brakes a no brainer for that crowd. At worst, road cyclists contend with a lot of water and road grime which can eat up rims in the winter for sure, so it's not 100% ideal either, but on balance I would take the tradeoffs with rim brakes over disc brakes for high end road riding and racing.

Will be interesting to see how it all shakes out. I don't think anything is a "done deal" just yet.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

kulivontot
Posts: 1163
Joined: Sun May 16, 2010 7:28 pm

by kulivontot

I think disc actually makes wheels weaker, not stronger, at least for the front for sure. The addition of a rotor pushes the non-driveside hub flange inwards resulting in a more dished wheel with less spoke tension on one side. On the rear it might actually help even spoke tension since the NDS flange is already farther from center than the DS, but once you account for 135mm or 142mm spacing it might come out as a wash. Point here is that if you want a stronger wheel with 28/28 lacing, disc brakes have nothing to do with it.

User avatar
Calnago
In Memoriam
Posts: 8612
Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

Agreed about being able to build wheels with 28/28 lacing really has nothing to do with discs, but then you'd be way behind the cool kids with their low spoked super light non disc wheels. With disks, they have to increase strength to accommodate the forces I described previously and that includes more spokes. So it would even things out.
Dishing the front wheel a bit does make things more complicated up front but they'd still be nowhere near the dish of a rear wheel so I think it would still be plenty strong. Agreed though that no dish is best where possible, and thus brings the conversation back to WHY discs. I just see more negatives than positives at this point but that may change down the road. Until then however...
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

pushstart
Posts: 461
Joined: Sat Jun 16, 2012 3:12 am

by pushstart

Yeah, because mtb doesn't put near as much stress on a wheel as a road bike, right? And you hear about all those mtb wheels folding in half on corners, right? ;)

The dishing in front I am sure is worse for strength than no dish, but not a practical concern. Not racing radially will make for stronger wheels too. My 28/28 wheels have taken beatings on- and off-road for many thousands of miles collectively now without issue.

25/24 is also a common OE configuration. My next race wheelset will probably be 24-spoke.

P.S. 135 and 142mm wheels are the same width as far as the flanges are concerned. 142 simply means that the axle extends to the outside of the frame (thru-bolt, so no "dropouts" per se).

kulivontot
Posts: 1163
Joined: Sun May 16, 2010 7:28 pm

by kulivontot

Yeah... but the point is 28/28 non-disc wheels will take beatings too.

Nefarious86
Moderator
Posts: 3669
Joined: Sun May 25, 2014 4:57 am

by Nefarious86

CBJ wrote:
Kermithimself wrote:I just don't get the need for disc brakes. If you want better breaking, use a wheel with an alu braketrack.


Dics brakes are so much better. I ride both alu brake track and dics almost every day. Modulation, power, control feel everything is just better. One example is when you have to do hard braking you need much less force which give you more control to steer the bike. When its wet its of course much much much better. I don't know if that is something the Pros will value but for everyday riders like most of us I think its better in the real world.

This, while I think it's overkill for racing its bliss for training lol.
Using Tapatalk

Fiery
Posts: 420
Joined: Sat Mar 16, 2013 9:21 am

by Fiery

Mr.Gib wrote:
Fiery wrote:Let me rephrase that: Mr. Gib, are you actually capable of locking up the front wheel and making it slide while riding in a straight line on dry pavement? Alternatively, are you capable of consistently braking so hard that the only way to avoid endoing is by decreasing the braking force?


The simple answer is yes.

What's the modulation like when being at that limit?

User avatar
Mr.Gib
Posts: 5548
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

Fiery wrote:
Mr.Gib wrote:
Fiery wrote:Let me rephrase that: Mr. Gib, are you actually capable of locking up the front wheel and making it slide while riding in a straight line on dry pavement? Alternatively, are you capable of consistently braking so hard that the only way to avoid endoing is by decreasing the braking force?


The simple answer is yes.

What's the modulation like when being at that limit?


Seems good to me - never stacked it. As you get to that limit you are slowing down quite a bit, the front end is heavily loaded, giving good front wheel traction, so even though you are already squeezing hard, it takes significant additional force to decelerate ever further. These big differences in hand effort, while taxing the sense of feel in the hand, seem to allow for more "fine tuning". The severe downward force also results in really good feedback about what your front tire is up to grip wise.

I think it is a great exercise to find a 10 or 15 percent grade, get the bike up to 50 km/h and practice how fast you can stop. Seen too many good riders with not the slightest clue of how to use their brakes. I live at the top of a 18% grade. I do this at the beginning of every ride. (My cool down at the end of the ride sucks though :D )
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

Nefarious86
Moderator
Posts: 3669
Joined: Sun May 25, 2014 4:57 am

by Nefarious86

Also for those of you raising the fluid boil issue, I managed to turn a front rotor black from heat and the caliper was still fine to touch, the ceramic pistons etc resist heat well and the ice tech pads draw the heat out fast. This was repeatedly abbusing them down a 15/20% grade wanting to test their limits.

Rotor has 3300km on it now and 0 issues. Still well above the wear limit and only on the second set of pads because I put fresh ones in before a 250km ride I did earlier in the year as a maintenance/issue prevention measure. Pads are still in my spares box and will go back in when I wear these front ones out. Original rear pads are still fine.
Image

My only gripe, black dust on my left shoe [emoji14]
Using Tapatalk

jeffy
Posts: 1325
Joined: Sun Oct 05, 2014 11:51 pm

by jeffy

Pretty fork. What bike?

Nefarious86
Moderator
Posts: 3669
Joined: Sun May 25, 2014 4:57 am

by Nefarious86

Kool-aid chariot [emoji14]

Image
Image
Using Tapatalk

Wingnut
Posts: 2196
Joined: Sat Jun 23, 2007 12:41 am

by Wingnut

I'm not really a fan of disc brakes and it'll be a long time if I ever get them but these look really tidy...

Image

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
andreszucs
in the industry
Posts: 737
Joined: Mon Nov 28, 2011 7:15 am

by andreszucs

Yes for disc brakes. It improves safety. Not like some BS marketing about aero here and there...hydro brakes actually makes a difference...not on aesthetics but in safety performance. It's like Dropper posts for MTB's.


Sent from my iPhone using Tapatalk

Post Reply