For those buying a new machine... disc or rim?

Discuss light weight issues concerning road bikes & parts.
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C36
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by C36

Last edited by C36 on Sun Nov 18, 2018 1:53 am, edited 2 times in total.

by Weenie


TobinHatesYou
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by TobinHatesYou

Imagine if people didn’t quickly adapt to the different braking characteristics of different cars. It’s a non-issue. Two of the dude’s acquaintances crashed as a result of operator error / misjudgment. Most of the time, better modulation means you are less likely to lock up as the “brake feel” granulation becomes finer or more precise.

MoPho
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Location: NorCal/SoCal

by MoPho

C36 wrote:
Sun Nov 18, 2018 1:53 am

As usual you play dumb.
The braking power is the one of the complete assembly, then how much resistive torque you can apply before losing grip.
Both systems can reach a point where you exceed what the tire can support.

I understood the disc brakes offered better modulation (and in controlled cases I agree, I hate the weak feel but yes you have better modulation) and here it appears that under emergency conditions those two guys didn’t benefit from this “superior modulation”.
Is it enough to make conclusions? No. Is it a valid perspective to consider... yes, I never had to do emergency brakes and I don’t know how disc would react, so this point interest me.

Note tomorrow I try the tarmac in both rim and disc in a trade show here



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As usual, you fail at reading comprehension



.

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C36
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by C36

MoPho wrote:
C36 wrote:
Sun Nov 18, 2018 1:53 am

As usual you play dumb.
The braking power is the one of the complete assembly, then how much resistive torque you can apply before losing grip.
Both systems can reach a point where you exceed what the tire can support.

I understood the disc brakes offered better modulation (and in controlled cases I agree, I hate the weak feel but yes you have better modulation) and here it appears that under emergency conditions those two guys didn’t benefit from this “superior modulation”.
Is it enough to make conclusions? No. Is it a valid perspective to consider... yes, I never had to do emergency brakes and I don’t know how disc would react, so this point interest me.

Note tomorrow I try the tarmac in both rim and disc in a trade show here



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As usual, you fail at reading comprehension
.
I wish, I would not be so painful to read you. Image
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MoPho
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by MoPho

C36 wrote:
Sun Nov 18, 2018 5:09 am

I wish, I would not be so painful to read you. Image
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Ah yes, the ole ad hominem attack, a sure sign you don't know what you're talking about. :thumbup:



.








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KevinM
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Joined: Fri Jun 29, 2018 11:37 am

by KevinM

bikeboy1tr wrote: No one is calling anyone an idiot
Still feel that way? 😂😂😂

bikeboy1tr
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by bikeboy1tr

KevinM wrote:
Sun Nov 18, 2018 7:33 pm
bikeboy1tr wrote: No one is calling anyone an idiot
Still feel that way? 😂😂😂
Haha well until they get rid of rim brakes there is going to be a shitload of name calling. Isnt good friendly debate such fun?
"Life is like riding a bicycle. To keep your balance you must keep moving"-Albert Einstein
2018 Colnago V2R Rim Brake
2014 Norco Threshold Disc Brake
2012 Time RXRS Ulteam Rim Brake
2008 Time VXR Rim Brake
2006 Ridley Crosswind Rim Brake

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C36
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by C36

c36 wrote: Note tomorrow I try the tarmac in both rim and disc in a trade show here
After an insurance issue that, as often, turns into a joke (but this time on my favor... paint damage = full bike price... sometime it your lucky day) I may replace the SuperSix Evo-2 HM and took the opportunity to test 2 Tarmac SL6 in Ultragra, Di2 for the Rim bike and classic for the Disc bike. Even if after my previous Disc / Rim comparison (2 SuperSix evo2 HM where I clearly prefered the Rim brake one), I though it was a good opportunity to compare a frame designed for both brake systems since the start (the SSevo was initially only Rim).

That was a 60km ride with almost 1000m elevation, first part with the rim, second part with the Disc. The Disc bike did all the descend (the rim just 3km to join the guy with the disc bike that was behind).
First both are really good bikes, I like how they respond but, and that's my #1 point of election: the rim frame is just more responsive, at the moment to accelerate, step on the pedals or sprint. That's consistent with what I recall from the 2 SS-Evo2 Disc / Brake comparison or what is available on magasines. There is also something I didn't like on the disc-fork, seems somehow harder but I would need more km to understand better.

I won't ever select a bike based on braking capabilities since you spend "99% of the time" not braking, but I still have interest how things evolve. The first part of the descent was severe with parts above the 15% (up to 22% on 140m) and discs are easy. I don't see them faster, the braking points are similar, the modulation was surprisingly similar (did recal more differences on previous rides) but it's just easier. That's a very minor advantage to me but could be to my wife (smaller hands, less force), now the Disc Brakes rubs were annoying... so were the carbon rim from my collegue shouting like a pig you try to kill (unsure if it was specific to Roval wheels, but boy that was ugly). Both brakes suffred from some degradation with heat, the disc brake become more "spongy", the rim brake needed a bit more force (but “touch” remained the same).

In short if I have to change bike today that would still be the rim-brake... just cause overall it's a better bike for me.
Yet have to test the venge but looking at the profiles here I doubt I would need it... but yet want to try it (full 9170).


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Last edited by C36 on Mon Nov 19, 2018 12:39 am, edited 1 time in total.

KevinM
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by KevinM

Interesting that you found the rim brake version to be more snappy since the disc version has thru axel. Really cool that you got to ride both side by side on a real ride to compare! That’s the best way to make your decision.

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C36
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by C36

KevinM wrote:Interesting that you found the rim brake version to be more snappy since the disc version has thru axel. Really cool that you got to ride both side by side on a real ride to compare! That’s the best way to make your decision.
Counter intuitive maybe, but consistent with all the comparisons that exist I keep posting this capture from the french magazine Le Cycle Image
I understood one of the brand complained that writing this was “not correct” ImageImage

Around a year ago I tested 2 cannondale supersix evo2 hm ultegra, same size (52), same everything (same colour!) but the braking system. And that’s what drove me to select the rim brake, the bike just feel more “dynamic”...
From a friend former Cannondale who gave me GL to quote him “Yes SS disc can’t replicate the behavior of SS rim brake, the reinforcement on the frame are a challenge. But you should try the future System6, you won’t have anything to compare to...”.

We may get there in the future (that’s why I had interest in the tarmac sl6 that is a “newer generation” than the SSe2... but from I tested so far... not yet.


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RocketRacing
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by RocketRacing

Rim brake vs disc brake (lets assume hydraulic disc) is tough to compare.

People are making a lot of generalizations. So it is time for me to generalize. It is like comparing brakes on my daily driver, to a ferarri. At street speeds, the brakes on the daily will feel smooth, and well balanced with lots of modulation. Thr ferrari will feel far to grippy, and it will be hard to be smooth.

At 100km/hr the daily driver will have good power and modulation, but on heavy use, it will be a bit more off/on in respose. The ferrari will still feel easy to overpower (too much braking) in response, so you still need to work to be smooth, but modulation is increasing.

At 200km/hr the daily driver struggles to stop the car. Braking is “all in” to hope to stop the car. There is no modulation. Hit the brakes and pray. The ferarri is now in it’s design element... at this speed, the brakes have as much, or as little power as you wish. You have modulation for days and the brakes feel incredible... like engineering perfection.

My lesson here is an oversimplification, but it is a reminder that brakes have a design for intended use... or rather mechanical characteristics that make it perform worse or better in certain circumstances. A carbon rim brake will perform differently from a dura ace rim brake vs a two pistom caliper, vs four piston trail focused caliper. performance, and modulation will depend on bike speed, rider weight, rim surface (lets simplify to wet or dry), and the degree of incline.

To cut to the chase, the carbon rim brakes in the dry, on a flat, at low speeds with a light rider may feel just great for modulation. The four piston trail brakes... will be an on/off switch trying to throw you over the bars if you use the same level of brake lever input. Now, put those same brakes on a heavy bike with heavy rider flying at high speed down a wet mountain, and the four piston setup now has far more modulation, and the carbon rim brakes are nothing more than clamp and pray.

Yes, some brakes/pads/braking surfaces are better than others, but my point is that every brake will have an intended performance sweet spot, and not all brakes were created (flex is bad), or set-up equil. It is less about which is better, and more which performs better (or is good enough) for your specific riding situation.

I am 60kg, so rim brakes are fine by me. I could probably get away with weight weenie flexy carbon rim brakes. If i were 160kg living in a wet hilly region... disc brakes would be an easy sell.

What is best all depends. Especially when you factor weight and and aero.

Bb13
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by Bb13

C36, could you compare sensations between Cannondale and Spe rim versions please.
I have one Supersix, for me, it’s thé best bike i’ve ever riden especially with bora35.
But the new Tarmac is on my short list for a new bike.
Thanks.

Rocket, you are right, every system has its own purpose, that’s why it would be great to still have the choice in the future.

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C36
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by C36

Bb13 wrote:C36, could you compare sensations between Cannondale and Spe rim versions please.
I have one Supersix, for me, it’s thé best bike i’ve ever riden especially with bora35.
But the new Tarmac is on my short list for a new bike.
Thanks.
Difficult, my SS is around 6.1 kg with 1100 g wheels and tubulars, the Tarmac was above 7 with quite deep wheels. so the cannondale was a lot nicer to climb, but on the flatter sections I liked a lot the tarmac stiffness, it’s very sharp to transmit the power, I felt that the wheels had a lot to do... but without the possibility to swap it was difficult to compare.
If I decide to change bike I will do another ride with different wheels to ensure I am able to separate frame and wheels behaviour.





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Calnago
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by Calnago

KevinM wrote:Interesting that you found the rim brake version to be more snappy since the disc version has thru axel.
Not sure why that surprises you. On early disc road bikes with a lightish fork and quick release skewers the uneven braking force at the axle would tend to twist the entire fork. Not a good feeling. Plus it puts more weight at the end of your steering axis (the axle)versus at the much stiffer end of the fork by the crown, affecting the “nimbleness” if you will. Thus forks have to beefed up and thru axles added in an attempt to counter the asymmetric braking forces from the disc placement. With a rim brake, it is a huge disc, perfectly centered and the braking forces are equal on each side. No “twisting” forces are occurring. And since the braking force originates at the rim, you don’t need to beef up or add spokes, or limit spoking patterns (no radial spoking with disc brakes), to handle the increased stresses being transmitted to the rim from hub through spokes when the braking force happens at the hub (disc). Again, the rim brake is a very simple, efficient and effective design.
Last edited by Calnago on Mon Nov 19, 2018 4:30 pm, edited 1 time in total.
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C36
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by C36

KevinM wrote:Interesting that you found the rim brake version to be more snappy since the disc version has thru axel.
Missed one interesting part. I am not sure the TA bring more stiffness and would be curious to see a real comparison.

Few years ago I recall a comparison of wheel stiffness based on different QR. I think there was no stiffness difference regardless of the QR. As long as hub and fork had no relative movement (thanks to QR compression) there is zero reason to change the stiffness.

TA came to solve the issue of the braking forces that could move the front hub in the fork (or outside in extreme cases). If we have no relative mvt with a QR and none either with the TA then the stiffness difference would remain the same unless the fork is structurally different.

Again I would be interested to see any lab number.



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by Weenie


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