Alu rim brakes vs carbon vs disc

Discuss light weight issues concerning road bikes & parts.
Morkai
Posts: 44
Joined: Thu Mar 01, 2018 2:00 am

by Morkai

I started cycling 4 years ago. Went from a hybrid city bike to endurance Whyte Wessex road bike to Trek Emonda SLR. All disc. The last rim brake bike I rode was $150 and over 20 years ago.

Lately I caught myself thinking about buying a new bike during a ride if the ride didn't feel smooth. Cleaning and relubing the drivetrain solves that problem :)
I like cleaning the bike on a sunny, rest day. What I don't like is fixing it.

This week the front rotor started rubbing. No rubbing at the end of a ride one day and rubbing at the start of a ride the next day... what?! Cleaned the pistons and success: no rubbing! Unless riding out of the saddle and throwing the bike from side to side :( But this is not the first time it happened and I should be able to fix it again (or it will disappear on its own). It's just annoying.

With the release of the new Emonda, Trek fixed what I don't like with the old one: slimmer head tube and hidden cables (with the Madone cockpit), so I was thinking about getting it, but after the disc problems I spent the night looking for potential rim brake bike and found an offer for a used S-Works Tarmac SL6 2018 with DA Di2 and no wheels for 4900€.

I have a B'TWIN Triban 540 with Mavic Aksium wheels with aluminium rim brake track that was never ridden outside attached to a turbo trainer. It has B'TWIN branded calipers with Tektro pads (are you supposed to be able to move the calipers with your hands or the bolts are not tight enough?) and the tires are blue Schwalbe 23mm for the rollers (I thought I would use the rollers outside during the pandemic - didn't happen).
Let's say I go out and test the B'TWIN rim brake setup.
My question is what can I expect in terms of braking in comparison to a Tarmac with Dura-Ace calipers and Campagnolo Bora WTO or Bontrager XXX wheels with 28mm tires? Better/worse?

I'm 62kg +/- 1kg and the terrain I ride is rolling +/- 2%, no mountains, very few up to 7% short hills.

by Weenie


Hexsense
Posts: 1218
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

Aluminum rim (Consider HED Jet4 plus, Jet6 plus):
Dry: just less smooth feeling vs disc. Power is still there.
Wet: lose more power than disc and the rim can wear down with contamination. But overall, work fine.


Carbon rim:
Dry: Less power but work just fine, just be careful on long descending. It can heat up and soften the rim. A very soften rim cannot withstand tire pressure and can eventually fail.
Wet: eh, plan for double the stopping distance vs disc.


Dura-ace caliper are almost all great. Except the under chainstay direct mount version which is a little underwhelming. All the normal mounts, and direct mount in other position are great. Thankfully, Tarmac mount rear direcr mount brake on seatstay so it is fine.
In wet, Dura-ace on carbon rim won't outperform cheap brake on aluminum rim IMO. However, in dry it might outperform your B'TWIN set-up.

c60rider
Posts: 573
Joined: Mon Feb 27, 2017 11:12 pm

by c60rider

If only it was so simple as to rate them 1, 2 or 3. What we don't want is yet another thread arguing over rim v disc so I would say go with whatever brake YOU want. It will brake perfectly well in all conditions. Just investigate thoroughly the pros/cons of each, setup, maintenance, noise etc but bear in mind the industry, and the written press, will have you believe that rim brakes are now obsolete and don't work, as they all want us to get rid of rim brake bikes and buy discs.

alcatraz
Posts: 3088
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Disc brakes on an emonda makes sense. It belongs in the hills where they are useful.

If you get a fairweather bike for flats then rim brakes are ok. Aero or maybe better, tt.

If I were you I'd try to learn more about the gear you have and try to maintain it as good as possible, before making big investments.

Mep
Posts: 522
Joined: Fri May 28, 2004 4:11 pm

by Mep

I have the same riding profile as you, and I don't head out to ride when it's raining, so rim brakes are a no brainer. I remember going from Mavic Ksyriums (aluminum) to Boras, and I felt that the Boras had more stopping power and modulation. Of course there are more variables than just the wheelset, but suffice to say that you shouldn't accept lower braking performance on carbon rims.
Last edited by Mep on Fri Jun 26, 2020 1:52 am, edited 1 time in total.

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Alexbn921
Posts: 501
Joined: Wed Apr 10, 2019 6:39 pm

by Alexbn921

I'm tall, heavy and ride in the mountains. Disks are the bee's knees. I will never ever go back. I have a dial gauge truing stand so my rotors and wheels are true to +-.001 inches. Without being able to true your rotors they can get warped and eye balling it is second rate.

Aluminum rim with Shimano brakes are the best you can get. Generally they are okay, but get overwhelmed at threshold.

Carbon rims are simply not ridable for me. I have tried them and they lacked enough power to stop me in a respectable distance. Longevity was also a concern with how expensive they are.

My wife is light and only rides flat areas. There is no reason for her to switch from aluminum rim to disks. I also don’t want to maintain them.

Imaking20
Posts: 2345
Joined: Fri Nov 18, 2011 5:19 am

by Imaking20

I think you'd be hard pressed to find a better rim brake surface than the Aeolus XXX.

Just going back from SL6 disc on Dura Ace to the rim brake version and XXX 4. So you know where I'd put my money.

FWIW, some of the nuisances you just described are what pushed me over the edge about disc. The "perks" of disc - I never needed. The downsides came anyway (even if they took awhile to show up).
Current:
Acid Mint Tarmac
Hakka MX

Retired:
Boone |Wilier Wonka|The Dentist|The Bucket List|Specialissima|Evo|T2|Blue|Project C6.0 | elt AR FRD|Colnago C59|S-Works Tarmac SL4|S-Works Venge|Wilier Cento1 SL|Tarmac SL2

mvcap
Posts: 138
Joined: Fri Apr 22, 2016 9:50 pm

by mvcap


Alexbn921 wrote:I have a dial gauge truing stand so my rotors and wheels are true to +-.001 inches. Without being able to true your rotors they can get warped and eye balling it is second rate.
I am new to disc brakes (SL6 with Ultegra r8000) and love the feel vs my other bikes with rim (Ultegra 6800). Although the rim brakes do stop well, I had no complaint, simply the hydraulic disc brakes feel smoother.

However, I haven't seen anything about truing rotors, can you please add to your comments? When / how often do you do this? Are you only aware they're out of true when you check them, or do you know it's time when they rub, or what?

Thanks!

alcatraz
Posts: 3088
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Alexbn921 wrote:
Fri Jun 26, 2020 2:28 am
I'm tall, heavy and ride in the mountains. Disks are the bee's knees.
Rim brakes are only as good as their weakest link. Brake surface / brake pads / brake calipers.

If you get the opportunity to try lets say a bora ac3 + bora red + shimano duraace caliper bike, try it out.

I'm light myself but some of my heavier 95-120kg friends have refrained from making large investments after trying better rim brake solutions. They didn't know such power was possible with rim brakes.

Imaking20
Posts: 2345
Joined: Fri Nov 18, 2011 5:19 am

by Imaking20

Campy red pads are a life hack
Current:
Acid Mint Tarmac
Hakka MX

Retired:
Boone |Wilier Wonka|The Dentist|The Bucket List|Specialissima|Evo|T2|Blue|Project C6.0 | elt AR FRD|Colnago C59|S-Works Tarmac SL4|S-Works Venge|Wilier Cento1 SL|Tarmac SL2

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Alexbn921
Posts: 501
Joined: Wed Apr 10, 2019 6:39 pm

by Alexbn921

My last bike had Dura Ace wheels and brakes. I tried several different pads and the Swiss stop ones where my favorite. It was the best of the best setup and the guy that bought it said they were the best brakes he had ever felt. I though they where subpar. To each their own. It’s very dependent on where you live and how you ride. Nothing will ever make me go back to antiquated rim brakes.

I find that rim brakes required regual maintance too. You need to get the little pieces of metal out of the pads and clean/scuff the brake track at least once a month.
Last edited by Alexbn921 on Fri Jun 26, 2020 4:43 am, edited 1 time in total.

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Alexbn921
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Joined: Wed Apr 10, 2019 6:39 pm

by Alexbn921

mvcap wrote:
Fri Jun 26, 2020 2:56 am

However, I haven't seen anything about truing rotors, can you please add to your comments? When / how often do you do this? Are you only aware they're out of true when you check them, or do you know it's time when they rub, or what?

Thanks!
Just like derailleur hangers disk are never perfect out of the box. I always true my rotors when new. Usually I can get them to +-.0005 and they stay true for 2-3 sets of pads or 4000+ miles. The truer they are the truer they will stay. Any high spots will drag more and retain more heat warping them faster. Park sells a rotor tool, but I got my setup from a now gone craftsman (RIP morning star tools).

I only check them if I'm checking the wheel too or they are giving me trouble.

On my mountain bike the rotors need attention every 500-1000 miles but I get them red hot and they are larger so small changes make a bigger differance. I also tend to bang them into things.
20160411_205840.jpg

mvcap
Posts: 138
Joined: Fri Apr 22, 2016 9:50 pm

by mvcap

Thanks Alex! Good info

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cveks
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Joined: Mon Aug 21, 2017 8:15 pm
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by cveks

Rim brakes all the way....

Either alu or carbon. With carbon wheels I climb better and faster, with alu rims I am bit slower but I have more stopping power and feel safer when going downhill on mountains.

I dont like disc brakes at all. What is point to invest thousands in bike, to make it lighter than usual, than add 500 grams to it with disc brakes?

My favorite setup for climbing mountains is bike with tubular carbon wheelset. Saves like 1000 grams over bike alu rims with disc brakes for example.

by Weenie


MyM3Coupe
Posts: 279
Joined: Thu Nov 24, 2016 10:32 pm

by MyM3Coupe

cveks wrote:
Fri Jun 26, 2020 6:58 am
Rim brakes all the way....
I dont like disc brakes at all. What is point to invest thousands in bike, to make it lighter than usual, than add 500 grams to it with disc brakes?
Absolutely brilliant assessment. In an industry/sport where weights are measured in grams, and drag in two significant figure watts, and some people want to put heavy motorcycle "dork discs" on road bike. It's just so counterintuitive. "Aero" carbon wheels are a waste for anyone but a GC contender. I forget the number, but didn't TOUR magazine test that the difference in drag between the worst and best wheels was a paltry 14 watts??

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