Disc brake advantages?

Discuss light weight issues concerning road bikes & parts.
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LeDuke
Posts: 1500
Joined: Sun Oct 07, 2012 2:39 am
Location: Front Range, CO

by LeDuke

Properly bedded in pads on even mid level brakes (I’m using Force 1) blow the doors off of rim brakes.

Granted, I live at 7,000ft in CO. And, in the summer, my rides will have several thousand feet of altitude change, and can go from 90+ degrees to below freezing. Rain and hail coming and going almost instantly after hours of blue skies.

Discs mean no risk of blow off, and no handling change because the rim/tire doesn’t heat up. Riding a steep descent and losing the ability to nail a corner because of your rim brakes? You can have that.



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spdntrxi
Posts: 2761
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

nickf wrote:
Sat Feb 09, 2019 7:59 pm
I have heard many complaints about road disc in both wet and dry conditions. Lack of power, noise, disc/caliper alignment noises. These bikes are coming from different shops so I don't think it's setup. There genuinely seems to be a trend of lackluster performance when it comes to disc brakes. That's in wet and dry conditions. Granted I live in Florida where there are no hills to be worried about when descending. The industry is really pushing disc as a solution to a problem that doesn't truly exist in the world of road bikes. My 4-year-old Bontrager carbon tubs brake tracks look just fine. Also, the wet weather performance thing is a moot point, myself and almost everyone I ride with avoids riding in the rain anyways.


I am on the fence about disc with my next allroad build, my requirements are to fit a 38c. I can fit 38s and even 40c tires between a set of trp mini v's on my Trek Crockett. I have done many many allroad events and 38s have proven to be plenty of tire and offer the best mix of size, weight, compliance, and stability. So other than needing to go with a tire that's 42c+ or 650b there is no true need for disc. But having that option would be nice, but is it worth the weight penalty and so-called improved braking performance? This is weight weenies after all. I for one am not cool with bolting on 500G+- for "improved brake modulation and wet weather performance" said every marketing team.

you are not ok with 500g for disc brakes you are not going to be ok with 650b fat arse tires ..even the 38/40c tires you speak are gonna be heavy

by Weenie


alcatraz
Posts: 2052
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

I'd like to descend next to a guy on disc brakes and see how much later he brakes before corners and such.

I want to get a feel to how much time I'll save by going disc, by watching and riding together with other riders.

Then I'll compare that to the time I'll lose climbing.

The problem is I spend a looot more time climbing than descending, so to save 2 seconds descending is hard, but save 2 seconds climbing is easy.

TheRich
Posts: 310
Joined: Tue Jan 01, 2019 1:36 am

by TheRich

alcatraz wrote:
Sun Feb 10, 2019 5:14 am
I'd like to descend next to a guy on disc brakes and see how much later he brakes before corners and such.

I want to get a feel to how much time I'll save by going disc, by watching and riding together with other riders.

Then I'll compare that to the time I'll lose climbing.

The problem is I spend a looot more time climbing than descending, so to save 2 seconds descending is hard, but save 2 seconds climbing is easy.
You'd lose that two seconds in the first tight corner if someone was actively trying to out brake you. The increased power and modulation allows more precise control of corner entry speed, where having less power and modulation causes over braking and lower entry speed.

Why do you think they're standard for mountain bikes?

alcatraz
Posts: 2052
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

We'd be dropping a lot of altitude in such a corner. Wouldn't that time lost be gained back on the climb?

You know how weightweenies like to equate grams into seconds saved and we'd have to say, well yes thats if the finish line is on a mountain top. Aero saves you time almost everywhere, except for steep climbs over x degrees. As such aero has trumped weight.

Aren't disc weenies similarly betting the finish line to be at the bottom of a steep descent and no climbs getting there?

We'll have to explain that you're only seeing the large benefit when you descend with inclinations over x degrees. When you're not in that specific situation you are constantly losing 1-2 watts on flats and x seconds carrying weight up a climb.

My point is, disc brakes will be much harder to push against weight than aero when it comes to saving time.

The "aero momentum" will not so easily be transformed into "disc brake momentum". There are many places where it doesn't rain, or there aren't steep descents. Then it makes no sense to take a penalty, and that's assuming the change was free of charge. Add in the money and it's even harder.

I guess the best thing for the industry to do is to try and squeeze out 2 watts aero gains to negate disc brake losses, while not providing a rim brake version. Then riders will have no choice but to go disc to stay competitive.

spdntrxi
Posts: 2761
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

I know the ops original attention was good... but this is just the same ole shit. Merge with others or close.

sparklywheels
Posts: 36
Joined: Fri Dec 07, 2018 6:12 pm

by sparklywheels

alcatraz wrote:
Sun Feb 10, 2019 5:53 am
We'd be dropping a lot of altitude in such a corner. Wouldn't that time lost be gained back on the climb?

You know how weightweenies like to equate grams into seconds saved and we'd have to say, well yes thats if the finish line is on a mountain top. Aero saves you time almost everywhere, except for steep climbs over x degrees. As such aero has trumped weight.

Aren't disc weenies similarly betting the finish line to be at the bottom of a steep descent and no climbs getting there?

We'll have to explain that you're only seeing the large benefit when you descend with inclinations over x degrees. When you're not in that specific situation you are constantly losing 1-2 watts on flats and x seconds carrying weight up a climb.

My point is, disc brakes will be much harder to push against weight than aero when it comes to saving time.

The "aero momentum" will not so easily be transformed into "disc brake momentum". There are many places where it doesn't rain, or there aren't steep descents. Then it makes no sense to take a penalty, and that's assuming the change was free of charge. Add in the money and it's even harder.

I guess the best thing for the industry to do is to try and squeeze out 2 watts aero gains to negate disc brake losses, while not providing a rim brake version. Then riders will have no choice but to go disc to stay competitive.
Aero trumps weight in a time trial, but in a road race gaps are usually made on climbs and once a rider is gone it is very tough to catch them on the descent. Attempting to do that is some pretty unusual race strategy. If one could hold a good wheel or two cresting the climb, the draft benefits when descending far outweigh aero equipment advantages. I’m not sure how much faster discs will be through the corners in the descent though. The issue remains that once you lose that wheel going up, you probably aren’t getting back on it.

alcatraz
Posts: 2052
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

You sound like a light rider chasing after a stronger but heavier rider. They can just coast past a light rider while descending. :lol:

Us lighter riders have to be more aero than those heavier riders to have a chance descending.

To bring the discussion back to point, the heavier riders will more likely swap to disc brakes first so we'll hopefully see if this change will open or close the gap to a lighter rider on rim brakes riding behind. I'm curious to find out.

tarmackev
Posts: 421
Joined: Sat Jan 15, 2011 9:59 pm

by tarmackev

sparklywheels wrote:
alcatraz wrote:
Sun Feb 10, 2019 5:53 am
We'd be dropping a lot of altitude in such a corner. Wouldn't that time lost be gained back on the climb?

You know how weightweenies like to equate grams into seconds saved and we'd have to say, well yes thats if the finish line is on a mountain top. Aero saves you time almost everywhere, except for steep climbs over x degrees. As such aero has trumped weight.

Aren't disc weenies similarly betting the finish line to be at the bottom of a steep descent and no climbs getting there?

We'll have to explain that you're only seeing the large benefit when you descend with inclinations over x degrees. When you're not in that specific situation you are constantly losing 1-2 watts on flats and x seconds carrying weight up a climb.

My point is, disc brakes will be much harder to push against weight than aero when it comes to saving time.

The "aero momentum" will not so easily be transformed into "disc brake momentum". There are many places where it doesn't rain, or there aren't steep descents. Then it makes no sense to take a penalty, and that's assuming the change was free of charge. Add in the money and it's even harder.

I guess the best thing for the industry to do is to try and squeeze out 2 watts aero gains to negate disc brake losses, while not providing a rim brake version. Then riders will have no choice but to go disc to stay competitive.
Aero trumps weight in a time trial, but in a road race gaps are usually made on climbs and once a rider is gone it is very tough to catch them on the descent. Attempting to do that is some pretty unusual race strategy. If one could hold a good wheel or two cresting the climb, the draft benefits when descending far outweigh aero equipment advantages. I’m not sure how much faster discs will be through the corners in the descent though. The issue remains that once you lose that wheel going up, you probably aren’t getting back on it.
Don’t think allowing a gap on a climb and trying to bridge back over on the descent is unusual strategy at all.
It happens on virtually every hill/mountain stage on every race.



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ymisyd
Posts: 29
Joined: Mon Nov 20, 2017 12:16 am

by ymisyd

sparklywheels wrote:
Sat Feb 09, 2019 7:32 am
I’m not looking to reignite the war between the disc and rim camps, but a reasonable debate of the two systems. I used to ride rim brakes on a full Dura Ace bike, and traded it for a disc braked bike with Ultegra 8020. I’d like to know why people prefer discs though, I just don’t get it personally :? I’m trying to hear different sides and opinions.

Discs are supposed to stop better in wet conditions, but the DA rim brakes on Reynolds Assault rims in pouring rain down a 60-70kph winding descent didn’t leave any additional power or modulation to be desired. Many say that discs stop better than rim brakes on carbon in the wet, but I haven’t noticed any improvement.

Secondly, the stopping power in the dry isn’t nearly as good as my old rim brakes. Stop and go conditions make my hands and fingers sore (I’m relatively weak) on my disks, which I’ve never experienced on rim brakes. To make an full power emergency stop, I feel like I need to get in the drops, whereas the rim bike stopped with ease even from the hoods. I’ve ridden three other bikes with Ultegra discs, so setup is unlikely to be the issue. The discs stop, but aren’t effortless like rim brakes are.

After the disc brakes were bled improperly once, the issue was not apparent with a quick inspection and only appeared after 40km of riding. This resulted in losing the front brake. With a rim setup, one can 100% confirm that they are good to go visually, and have fewer points of failure compared to a disc system.

Finally, discs cost more, especially separate group sets. They weigh more, which doesn’t sound like much but the extra 500g or so in a mid ranged disc bike is a few seconds slower on uphill segments. Being someone that spends weeks tweaking every aspect of diet and training, it takes many weeks to take off a single pound. Oftentimes it isn’t even possible.

What are your thoughts and experiences?
Sorry, but reignite the war is exactly what you're trying to do. You can argue about aesthetics and weight all day, but there is no way you can validate your performance arguments.

Nefarious86
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by Nefarious86

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