rbent Forum - Disc brakes vs rim brakes

Tiger_Mike rbent member Posts: 208	Disc brakes vs rim brakes Apr 14^th, 2015, 8:18pm I'm thinking about a P38 build, and I'm mulling over brake choices. Is there any compelling reason to choose disc brakes over rim brakes?
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LightningPilot

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Re: Disc brakes vs rim brakes
Reply #1 - Apr 14^th, 2015, 8:53pm

Quote from Tiger_Mike on Apr 14^th, 2015, 8:18pm:

I'm thinking about a P38 build, and I'm mulling over brake choices. Is there any compelling reason to choose disc brakes over rim brakes?

The rim brakes are hard to adjust and can still screech like banchees. If I was doing a new build, I'd go for disc, says the girl with two p38s.

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« Last Edit: Apr 14^th, 2015, 8:54pm by LightningPilot »

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MrWizard

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Re: Disc brakes vs rim brakes
Reply #2 - Apr 14^th, 2015, 9:55pm

Quote from LightningPilot on Apr 14^th, 2015, 8:53pm:

Quote from Tiger_Mike on Apr 14^th, 2015, 8:18pm:

I'm thinking about a P38 build, and I'm mulling over brake choices. Is there any compelling reason to choose disc brakes over rim brakes?

The rim brakes are hard to adjust and can still screech like banchees. If I was doing a new build, I'd go for disc, says the girl with two p38s.

The guy with two P38s and one R84 agrees completely .. the rim brakes Tim uses by default are old-MTB V brakes. They are a PIA. Go with Disc. I converted my voyager to disc and I am so happy about it, I kick myself for not doing it years back. The only P38 that hasn't been converted is the one set up for indoor riding which has the brakes removed and replaced with "reverse track" "forward track" levers for controlling the audio. (yes I'm a nerd, stop laughing)

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Monkeywrangler22 Five Star Member rbent member Posts: 1308	Re: Disc brakes vs rim brakes Reply #3 - Apr 15^th, 2015, 6:23am If you go disc, invest in the TRP HY-RD ones. Better than BB7's by far. I will eventually, when budget permits, upgrade my Encore to the TRP discs.
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FlyingLaZBoy Moderator '16 ICE SprintX fs, '16 Rocket, '12 KHS Mocha Posts: 5803	Re: Disc brakes vs rim brakes Reply #4 - Apr 15^th, 2015, 11:32am Discs work SO much better in wet conditions...
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Bud_Bent

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Re: Disc brakes vs rim brakes
Reply #5 - Apr 15^th, 2015, 9:30pm

Quote from FlyingLaZBoy on Apr 15^th, 2015, 11:32am:

Discs work SO much better in wet conditions...

That's not been my experience at all. Yes, disc brakes can lock up the wheel much better when things are wet, but it becomes the tire that slides on the pavement rather than the brake pads that slide on the rim. I found that I actually had better stopping control in wet conditions with the rim brakes than the disc brakes, and ended up wishing I had never converted to disc brakes on my commuting setup. When I sold the Stratus XP and started commuting with the Xstream instead, I went back to rim brakes.

Vee brakes that have an arch, like the Avid Arch Rival brakes, can really lock up wheels, even on a tandem. I have them on my Screamer, and Greg can testify to how they can lock up the wheels, as he witnessed Rose and I skidding with the rear wheel locked up. I had to learn to modulate them like I did disc brakes, to keep from locking up a wheel too easy. But, on wet pavement, they don't lock up nearly as easy as disc brakes do, so I like them better than the disc brakes I had on the EZ Tandem. YMMV.

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« Last Edit: Apr 15^th, 2015, 9:41pm by Bud_Bent »

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MrWizard

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Re: Disc brakes vs rim brakes
Reply #6 - Apr 16^th, 2015, 10:48am

Quote from Bud_Bent on Apr 15^th, 2015, 9:30pm:

Quote from FlyingLaZBoy on Apr 15^th, 2015, 11:32am:

Discs work SO much better in wet conditions...

That's not been my experience at all. Yes, disc brakes can lock up the wheel much better when things are wet, but it becomes the tire that slides on the pavement rather than the brake pads that slide on the rim.

Isn't this a function of how hard you pull the lever back ? If you don't want it to lock up, modulate. (oh $h*t moments not withstanding) This is why I always liked hydraulic vs cables .. you can 'feel' how much breaking was applied. At least I could, or perhaps i was just convinced that I could because I overpaid for the fluidics when a cable would have worked. Wink

Of course, we can talk about drum brakes now .. for true rubber wrenching off the rim lockup power. http://www.sturmey-archer.com/en/products/detail/xl-sd .

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rcko

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Re: Disc brakes vs rim brakes
Reply #7 - Apr 17^th, 2015, 6:41pm

Riding both, trp cable actuated hydro reservoir on caliper discs on my GT Grade and rim brakes on Synapse

Hydro offers superior modulation and for a given lever pressure more braking power than the rim brakes.

However, tire contact patch is an issue, and that applies to both styles of brake. I can lock up either with enough lever pressure. So from a power perspective both are powerful. Actually the rim brake has more leverage...

If u got disc brake mnts and can afford the hydros I highly recomend the TRP hydro units. Remeber to bed the pads on ur first few rides to obtain full authority.

Ur other tuning option is disc rotor diameter. I am running 160mm.

Disc take a bit more care to align properly when doing wheel skewers. Just takes a bit more careful alignment than rim brakes.

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« Last Edit: Apr 17^th, 2015, 6:45pm by rcko »

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Bud_Bent Moderator Posts: 3311	Re: Disc brakes vs rim brakes Reply #8 - Apr 17^th, 2015, 11:19pm Yes, what it takes to lock up wheels is very different on wet pavement as opposed to dry pavement, and you have to learn how hard you can brake without locking them up on wet pavement, not so easily done, even with brakes that modulate well. With many rim brakes, you can't lock them up at all when the pads are wet, though.
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aikigreg

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Re: Disc brakes vs rim brakes
Reply #9 - Apr 18^th, 2015, 12:53am

That was a scary moment, Bud.

I'm tempted to go to disc on the m5 to eliminate my leg hitting the brake. I've got a bad abrasion from Bessie's Creek on the back of my thigh from it. Tried a simkins egg brake which was narrow and perfect, except it was finicky and started rubbing the tire.

I need a narrow brake with decent stopping power, but I don't want to change every bike I own to disc. Also, since the uci approved the use of discs in three pro peloton, we're going to see some radical changes over the next year. Best to wait I think.

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jayg

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Re: Disc brakes vs rim brakes
Reply #10 - Apr 18^th, 2015, 10:48am

Quote from Bud_Bent on Apr 17^th, 2015, 11:19pm:

With many rim brakes, you can't lock them up at all when the pads are wet, though.

My Musashi came equipped from the factory with Tektro caliper brakes and pads and Avid disc brake handles. Got caught in a downpour on a hilly pay ride. Brakes were almost totally ineffective, after the pads got wet (175 lb. bike/rider combo).

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Bud_Bent

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Re: Disc brakes vs rim brakes
Reply #11 - Apr 18^th, 2015, 4:39pm

Quote from jayg on Apr 18^th, 2015, 10:48am:

My Musashi came equipped from the factory with Tektro caliper brakes and pads and Avid disc brake handles. Got caught in a downpour on a hilly pay ride. Brakes were almost totally ineffective, after the pads got wet (175 lb. bike/rider combo).

Yes, many rim brakes are like that. But, if you replace the original pads with better ones for wet riding (I like the Kool Stop in Salmon), they will stop the bike. Many still won't lock up the wheel when they're wet, but locking up the wheel doesn't help anyway.

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jayg

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Re: Disc brakes vs rim brakes
Reply #12 - Apr 18^th, 2015, 11:15pm

Quote from Bud_Bent on Apr 18^th, 2015, 4:39pm:

Quote from jayg on Apr 18^th, 2015, 10:48am:

My Musashi came equipped from the factory with Tektro caliper brakes and pads and Avid disc brake handles. Got caught in a downpour on a hilly pay ride. Brakes were almost totally ineffective, after the pads got wet (175 lb. bike/rider combo).

Yes, many rim brakes are like that. But, if you replace the original pads with better ones for wet riding (I like the Kool Stop in Salmon), they will stop the bike. Many still won't lock up the wheel when they're wet, but locking up the wheel doesn't help anyway.

The first thing I did after the no-brakes incident was to install Salmon pads. Never got to test them in a downpour. To be honest, the bike's stopping power was less than satisfactory, before the no-brakes incident. I eventually replaced the long-pull Avid brake handles that came with the bike with short-pull Shimano caliper brake handles. The Shimano levers can apply up to a 60% greater force to the brake cables than the Avid levers. The brakes are now satisfactory. I've ridden the bike in the rain several times, since I replaced the levers, but not in a downpour. Haven't noticed any great loss of effectiveness (Still using Salmon pads).

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FlyingLaZBoy Moderator '16 ICE SprintX fs, '16 Rocket, '12 KHS Mocha Posts: 5803	Re: Disc brakes vs rim brakes Reply #13 - Apr 20^th, 2015, 1:15pm Good point about wheel lockup / skidding, Bud.... I locked up the wheels on my SXP in the rain, once (even with rim brakes), and the tires started skidding and took me down...
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Bud_Bent

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Re: Disc brakes vs rim brakes
Reply #14 - Apr 20^th, 2015, 5:25pm

Quote from jayg on Apr 18^th, 2015, 11:15pm:

The first thing I did after the no-brakes incident was to install Salmon pads. Never got to test them in a downpour. To be honest, the bike's stopping power was less than satisfactory, before the no-brakes incident. I eventually replaced the long-pull Avid brake handles that came with the bike with short-pull Shimano caliper brake handles. The Shimano levers can apply up to a 60% greater force to the brake cables than the Avid levers. The brakes are now satisfactory. I've ridden the bike in the rain several times, since I replaced the levers, but not in a downpour. Haven't noticed any great loss of effectiveness (Still using Salmon pads).

There are also brake levers which can adjust to be either long or short pull. Those are nice to help get the pressure just where you want it.

Quote from FlyingLaZBoy on Apr 20^th, 2015, 1:15pm:

Good point about wheel lockup / skidding, Bud.... I locked up the wheels on my SXP in the rain, once (even with rim brakes), and the tires started skidding and took me down...

Yes, to me, it's the hardest part of riding in the rain: figuring out how to do the best job of stopping, without laying the bike down. Every set of brakes is different, and how slick the roads are changes, and has a lot to do with how easy the wheels lock up. I've never liked riding on wet roads, and I still don't.

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« Last Edit: Apr 20^th, 2015, 5:26pm by Bud_Bent »

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