Disc brakes or not

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cyclotaur
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Re: Disc brakes or not

Postby cyclotaur » Tue Apr 17, 2018 7:17 pm

I have two bikes at the moment - one a rim-braked CX with Avid Shorty Ultimate cantis, and a newish gravel/all-rounder with TRP Spyre C cable discs, probably the best cable discs around.

Obviously the discs are much better than cantis !! And in all conditions, and it's the cantis that squeal if not clean or perfectly set up. :wink:

However....I recently sold a road bike with 105 rim brakes and they were excellent in good conditions. I rarely rode that bike in bad conditions. If you can pick the road/weather conditions rim brakes are fine, lighter, cheaper etc. And if conditions change while you're out then you have to adjust anyway - that's just sensible riding.

Unless you're racing....in which case - well I don't race, so - not my problem !! :lol:
Here's my blog - A bit of fun :)
"Riding not racing...."

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Comedian
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Re: Disc brakes or not

Postby Comedian » Mon May 14, 2018 2:10 pm

I'll chip in again. Ever since the disc roadie discussion has been a thing.. I've been saying that discs will cause a loss in compliance of the front end of the bike. Simply because moving the braking force to the far end of one of the forks would require significant stiffening of the forks to cope with these different asymmetric braking loads. I knew that the basically all the compliance in the front of the bike all comes from either the tyre or the fork (with the scraps coming from the bars and bar tape.).

Not all rim brake bikes have compliant forks. If you ride a rim bike without compliance you might not pick a difference. If you are the sort of person who doesn't really pick up on nuances like compliance then you probably won't care either. I knew that some people did notice though.. with people like specialized saying so much - and introducing their "future shock" to combat this problem. Of course the Canyon Grail..

On Saturday I did a ride that was undulating, twisty and rough. (Brookfield for those following at home). I've ridden this in the past on my rim brake bike with a harsh non compliant fork, and it wasn't really pleasurable. But Saturday I hammered it on my bike with the ENVE fork and cockpit. I was astonished how compliant and grippy the whole thing was. This is a kind of safety I really wouldn't want to loose. Very enjoyable too.

Last week a cycling reviewer called this out as well. James Huang said discussed this at length.. but when summarising why he wouldn't buy the bike....

This one retains nearly everything that is good about the rim-brake edition, but there’s a noticeable sacrifice in ride quality with the stiffened disc-specific fork, not to mention the extra weight of the disc-brake componentry.


https://cyclingtips.com/2018/05/canyon-aeroad-cf-slx-disc-long-term-review/

So I fully expect the pro disc to blast away.. but I really think this is something that people should be aware of. Maybe not everyone will notice or care for sure. But some might and it might not be obvious until well after the shop has your money.

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CaffeineAU
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Re: Disc brakes or not

Postby CaffeineAU » Mon May 14, 2018 2:27 pm

In contrast, the rear of the bike can be more compliant, as you don't need beefy seat stays to support a rim brake.

Swings and roundabouts...

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MichaelB
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Re: Disc brakes or not

Postby MichaelB » Mon May 14, 2018 2:52 pm

If you are selectively going to quote to support your argument (which is fair enough), make sure there aren't other quotes that also support discs as being better than the rim version .....

It’s once you crest the top of the climb and start rocketing down the other side that this new disc-equipped version can really spread its wings. The direct-mount version of Shimano’s Dura-Ace rim-brake calipers are about as good as it gets, with very good power, excellent lever feel, and great control. But it still can’t compare with what even Shimano’s Ultegra-level hydraulic disc brakes offer on the road, especially in wet conditions and when using carbon rims. There’s a weight penalty for sure, and were I still living in the flatter Midwestern area of the United States, I likely wouldn’t feel compelled to go this route. But I live in Colorado, where descents can last 20 minutes, and I’ll happily lug a couple hundred extra grams uphill if it makes for a faster and more controlled flight back into town.
(my bolding)

And then this, to expand a bit more re the rougher cockpit feel ....

This new disc-brake fork is necessarily beefed up relative to the rim-brake Aeroad CF SLX version, and the ride comfort seems to suffer as a result. Compounding the issue is the integrated cockpit; it’s a gem when muscling the front end around, but combined with the rougher-riding fork, it transmits every bit of road texture to your hands, for better or worse.
Fair enough the disc fork is a significant contributor to the changed feel (rim & disc use 23C tyres, but different rims), but the cockpit also has an impact. BTW, what cockpit is used on the Rim version ?

Re the weight, interesting, he only quotes the weight of the bike tested :

Actual weight, without pedals, was 7.70kg (16.98lb) for a larger-than-it-sounds size XS.

But doesn't mention the amount of weight difference. A link in the article takes you to Canyon Aeroad CF SLX 9.0 Di2 (Dura Ace) which weighs in at 6.86kg for a M frame, but has completely different wheels & groupset, so can't compare.

I'd be interested to see what the ACTUAL difference is between the disc/rim versions.

Anyway, if you like Rim brakes fine. The comments are interesting, and what you quoted is correct, but you missed the other points that seem to contradict/moderate his opinion.

Meh, I'd have one in a heartbeat, but as Mr Huang says,
I’m still not buying this one, but it’s only because I don’t have the money.

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Comedian
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Re: Disc brakes or not

Postby Comedian » Mon May 14, 2018 5:37 pm

MichaelB wrote:If you are selectively going to quote to support your argument (which is fair enough), make sure there aren't other quotes that also support discs as being better than the rim version .....

It’s once you crest the top of the climb and start rocketing down the other side that this new disc-equipped version can really spread its wings. The direct-mount version of Shimano’s Dura-Ace rim-brake calipers are about as good as it gets, with very good power, excellent lever feel, and great control. But it still can’t compare with what even Shimano’s Ultegra-level hydraulic disc brakes offer on the road, especially in wet conditions and when using carbon rims. There’s a weight penalty for sure, and were I still living in the flatter Midwestern area of the United States, I likely wouldn’t feel compelled to go this route. But I live in Colorado, where descents can last 20 minutes, and I’ll happily lug a couple hundred extra grams uphill if it makes for a faster and more controlled flight back into town.
(my bolding)

And then this, to expand a bit more re the rougher cockpit feel ....

This new disc-brake fork is necessarily beefed up relative to the rim-brake Aeroad CF SLX version, and the ride comfort seems to suffer as a result. Compounding the issue is the integrated cockpit; it’s a gem when muscling the front end around, but combined with the rougher-riding fork, it transmits every bit of road texture to your hands, for better or worse.
Fair enough the disc fork is a significant contributor to the changed feel (rim & disc use 23C tyres, but different rims), but the cockpit also has an impact. BTW, what cockpit is used on the Rim version ?

Re the weight, interesting, he only quotes the weight of the bike tested :

Actual weight, without pedals, was 7.70kg (16.98lb) for a larger-than-it-sounds size XS.

But doesn't mention the amount of weight difference. A link in the article takes you to Canyon Aeroad CF SLX 9.0 Di2 (Dura Ace) which weighs in at 6.86kg for a M frame, but has completely different wheels & groupset, so can't compare.

I'd be interested to see what the ACTUAL difference is between the disc/rim versions.

Anyway, if you like Rim brakes fine. The comments are interesting, and what you quoted is correct, but you missed the other points that seem to contradict/moderate his opinion.

Meh, I'd have one in a heartbeat, but as Mr Huang says,
I’m still not buying this one, but it’s only because I don’t have the money.


You are probably right.. I did ignore pretty much everything else because I thought that was all pretty obvious. I'm pretty chuffed that we've at least got to the point of acknowledging that adding a disc brake fork has an effect on compliance. That's a win.

I've never heard the suggestion that adding disc brakes has an effect on rear compliance. I understand the issues but you could also argue that asymmetrically stiffening the rear triangle on one side could cause other issues.. The rear triangle is nowhere near as critical as the front because it's closed and is built to carry far higher loadings.

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Comedian
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Re: Disc brakes or not

Postby Comedian » Thu May 17, 2018 1:12 pm

And today's reality interruption...


The 54cm sample sent for review weighed 7.94kg/17.5lb without pedals or bottle cages, which doesn’t do much to support the notion that the Émonda is a lightweight race bike. For those hoping for a lighter bike, they can opt for the SLR 6 Disc that promises a weight saving of 700-800g (depending on frame size), but it costs almost twice as much as the SL 6 Disc. Alternatively, the SL 6 with rim brakes provides almost the same kind of weight saving (600-700g) and actually costs less than the disc-brake version.


https://cyclingtips.com/2018/05/trek-2018-emonda-sl-6-disc-review/

This quote I agree with. If you really want disc brakes then go for it.

For those contemplating such an upgrade, the choice of brakes may create some consternation, however much of the controversy surrounding disc brakes has died down. Quite simply, discs have become a legitimate option for road bikes and are now future-proof to some degree, so buyers can decide the matter on the basis of appeal. In this regard, the Émonda may be a little late to the party, but the second-generation frameset gives shoppers both options to consider.

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Comedian
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Re: Disc brakes or not

Postby Comedian » Wed May 23, 2018 12:27 pm

Great article on CTips today about disc brake maintenance.

https://cyclingtips.com/2018/05/complete-faq-to-road-disc-brakes/

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P!N20
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Re: Disc brakes or not

Postby P!N20 » Wed May 23, 2018 1:32 pm

My spinning disc brake cut off my left leg. What do I do?

Bugger. Are you sure it wasn’t the race fencing? Actually, it was probably the chain ring. Either way, you should probably seek medical attention.

Did laugh.

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Thoglette
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Re: Disc brakes or not

Postby Thoglette » Wed May 23, 2018 2:04 pm

Comedian wrote:Great article on CTips today about disc brake maintenance.

https://cyclingtips.com/2018/05/complete-faq-to-road-disc-brakes/

I do like the humour. :D

Shame it's still contains some "marketing spin", (to be polite).
Cycling tips wrote:By removing the brake caliper from the fork crown or seatstay bridge, manufacturers have been able to greatly increase tyre clearance and improve frame compliance


Now, I am considering adding a disk to the back of my non-disk bike. Not because they say it can't be done but because disk-only 650B wheels are starting to appear on council rubbish pickups.
Stop handing them the stick! - Dave Moulton
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Comedian
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Re: Disc brakes or not

Postby Comedian » Wed May 23, 2018 4:03 pm

Thoglette wrote:
Comedian wrote:Great article on CTips today about disc brake maintenance.

https://cyclingtips.com/2018/05/complete-faq-to-road-disc-brakes/

I do like the humour. :D

Shame it's still contains some "marketing spin", (to be polite).
Cycling tips wrote:By removing the brake caliper from the fork crown or seatstay bridge, manufacturers have been able to greatly increase tyre clearance and improve frame compliance


Now, I am considering adding a disk to the back of my non-disk bike. Not because they say it can't be done but because disk-only 650B wheels are starting to appear on council rubbish pickups.

How would you mount the caliper? Changing to a disc fork in general wouldn't be too hard for most road bikes, but fitting a rear caliper could be tricky.

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Thoglette
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Re: Disc brakes or not

Postby Thoglette » Wed May 23, 2018 5:59 pm

Comedian wrote:How would you mount the caliper? Changing to a disc fork in general wouldn't be too hard for most road bikes, but fitting a rear caliper could be tricky.

DIY - pretty much the same way some m'cycles do it - hang the caliper on a something which pivots on/near the axle; use the disk to keep the caliper aligned and keep the reaction rod in tension.

Or I could get lazy and buy one of the many disc brake adapters (e.g. A2Z adapters). All sorts out there.

At the front my forks are getting more "retro" and less disc/k compatible with every purchase. But I'm not into downhill.
Stop handing them the stick! - Dave Moulton
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