Disc Brakes — Hydraulic vs. Mechanical?

[vvill]

@hozn 160751 wrote:

Yeah, I do think that 160/160 is prudent, but road descents are also a lot less steep than MTB descents — especially the ones where people fit 200+mm rotors. On the road one can brake hard and release to cool the rotors, but good luck doing that sliding down a mountain on dirt.

Yeah I ran 160/160 on almost all my disc brake bikes (5+ ?). The only exception was my Kona Jake which was 140s for most of the time, but I decided I preferred 160s across the board.

[huskerdont]

So why do so many bike makers do 160/140 for CX/road, with the 160 in the front? It seems you’d want the greater stopping power in the rear so would have 160 there. Is space for 160 in the rear a problem with some frames?

[drevil]

@huskerdont 160778 wrote:

So why do so many bike makers do 160/140 for CX/road, with the 160 in the front? It seems you’d want the greater stopping power in the rear so would have 160 there. Is space for 160 in the rear a problem with some frames?

Most of your stopping power is in the front, especially as your weight shifts forward while braking.

[huskerdont]

@drevil 160780 wrote:

Most of your stopping power is in the front, especially as your weight shifts forward while braking.

While this is true, one of the first things you learn mountain biking is not to be over-reliant on the front brake lest you go over the bars. So even road biking, I tend to use the rear brake, then augment with the front when needed, and I’d personally prefer more power in the back. If I can’t (intentionally) lock up the back wheel, the brakes don’t feel powerful enough for me.

[TwoWheelsDC]

@drevil 160780 wrote:

Most of your stopping power is in the front, especially as your weight shifts forward while braking.

On a motorcycle, at least, it’s something like 80% of stopping power is on the front…hence, most motos have dual discs up front and tiny, single discs in the rear. Rear brake is more for slow speed maneuvering, particularly on loose surfaces. I’m actually surprised dual front discs on MTBs haven’t become a thing.

[hozn]

@huskerdont 160785 wrote:

While this is true, one of the first things you learn mountain biking is not to be over-reliant on the front brake lest you go over the bars. So even road biking, I tend to use the rear brake, then augment with the front when needed, and I’d personally prefer more power in the back. If I can’t (intentionally) lock up the back wheel, the brakes don’t feel powerful enough for me.

I’d disagree with this; the front brake is the one to use when you want to stop – on road or mtb. The rear is great for shaving off some speed or control or when there’s a high penalty for locking up the front tire — e.g. when traction is critical like in turns. Yes, you can go over the bars if you lock up your front wheel. I’ve certainly done it, but I attributed that to user error (not knowing my brakes very well or not appropriately shifting my weight back behind the saddle) and not a flawed stopping strategy. I would also suggest that locking up the rear wheel is a lot easier than locking up the front wheel because of the weight distribution (when braking), and if you’re locking up the rear wheel faster with bigger brakes this isn’t helping you stop faster. Of course, the point is never to lock up the wheels at all; ideally the brakes have enough power to make locking up easy but enough modulation to make it completely avoidable.

That said, I do think having a bigger rear rotor is nice. Switching from 140 to 160 on the CX bike was a big improvement; I lost my front brake once on the commute home and the larger rotor made me more comfortable stopping with just the rear brake. On cx or road bikes with shorter chainstays the issue is frame clearance, but I think most cx/gravel frames will fit a 160 (?) even if the bikes ship with 140s in back by default.

[hozn]

@TwoWheelsDC 160786 wrote:

On a motorcycle, at least, it’s something like 80% of stopping power is on the front…hence, most motos have dual discs up front and tiny, single discs in the rear. Rear brake is more for slow speed maneuvering, particularly on loose surfaces. I’m actually surprised dual front discs on MTBs haven’t become a thing.

I’m guessing that it would make sense for downhill (?) — but sounds like there’s a pretty big system design hurdle to get over there: new front hub standard, new fork standard, new brake/calipers system. Whereas just fitting larger and larger rotors can be done w/o any big system changes and I guess has been sufficient to-date. But sounds like it’d be pretty cool!

[huskerdont]

@hozn 160794 wrote:

I’d disagree with this; the front brake is the one to use when you want to stop – on road or mtb. The rear is great for shaving off some speed or control or when there’s a high penalty for locking up the front tire — e.g. when traction is critical like in turns. Yes, you can go over the bars if you lock up your front wheel. I’ve certainly done it, but I attributed that to user error (not knowing my brakes very well or not appropriately shifting my weight back behind the saddle) and not a flawed stopping strategy. I would also suggest that locking up the rear wheel is a lot easier than locking up the front wheel because of the weight distribution (when braking), and if you’re locking up the rear wheel faster with bigger brakes this isn’t helping you stop faster. Of course, the point is never to lock up the wheels at all; ideally the brakes have enough power to make locking up easy but enough modulation to make it completely avoidable.

That said, I do think having a bigger rear rotor is nice. Switching from 140 to 160 on the CX bike was a big improvement; I lost my front brake once on the commute home and the larger rotor made me more comfortable stopping with just the rear brake. On cx or road bikes with shorter chainstays the issue is frame clearance, but I think most cx/gravel frames will fit a 160 (?) even if the bikes ship with 140s in back by default.

So you’re saying I’ve been doing it wrong all this time?

Really, that’s okay, I don’t think we’re too far off on this. If stopping (not just slowing) while MTBing, I’ll almost always use the front as well. I rarely lock up the rear tire, and of course don’t want to because skidding is slower stopping. But when just slowing down, I usually just use the rear, and that habit has transferred to road riding as well, correct or no.

I just wonder that since the rear brake doesn’t do as well anyway, that’s where there should be more power to compensate. But I suppose if that extra power were to make the tire lock, that would be counterproductive.

[TwoWheelsDC]

@hozn 160796 wrote:

new front hub standard, new fork standard, new brake/calipers system.

Seems like the perfect opportunity to make more money!

[vvill]

@huskerdont 160797 wrote:

Really, that’s okay, I don’t think we’re too far off on this. If stopping (not just slowing) while MTBing, I’ll almost always use the front as well. I rarely lock up the rear tire, and of course don’t want to because skidding is slower stopping. But when just slowing down, I usually just use the rear, and that habit has transferred to road riding as well, correct or no.

I just wonder that since the rear brake doesn’t do as well anyway, that’s where there should be more power to compensate. But I suppose if that extra power were to make the tire lock, that would be counterproductive.

I think I use both front + rear brakes. I’ve had a few occasions on commutes braking hard where the rear wheel did start to lift up (e.g. avoiding hitting a car suddenly pulling out) but I’m yet to go over the bars that way. Otherwise the only time I’ve gone over the front bars from overzealous front brake usage has been playing around on my MTB in the backyard, getting a feel for the brakes and bike in general.

I don’t think I had issues stopping on 140 for what I used it for, but it did seem silly to have 140 just for weight savings/aero-roadie aesthetic when the whole point of having disc brakes is better braking. The hassle of ordering/maintaining/installing different rotor sizes on my wheelsets led me to 160 F/R.

[Tania]

@huskerdont 160785 wrote:

While this is true, one of the first things you learn mountain biking is not to be over-reliant on the front brake lest you go over the bars.

I did a weekend MTB clinic up in PA a few weeks ago and one of the first things we did was braking drills. After a few easy drills, she had us pick up speed and then slam on the front brake using only the front brake. No one slid, and no one went over the bars…because we all had our weight back. But it was a good lightbulb moment for me and now I’m a majority front braker – more so on a mtb. When commuting or road/MUP riding I’m an equal opportunity braker. We’ll see if my new braking skills translates to the cx bike in wet grass, mud and frost this Fall.

[huskerdont]

@Tania 160809 wrote:

I did a weekend MTB clinic up in PA a few weeks ago and one of the first things we did was braking drills. After a few easy drills, she had us pick up speed and then slam on the front brake using only the front brake. No one slid, and no one went over the bars…because we all had our weight back. But it was a good lightbulb moment for me and now I’m a majority front braker – more so on a mtb. When commuting or road/MUP riding I’m an equal opportunity braker. We’ll see if my new braking skills translates to the cx bike in wet grass, mud and frost this Fall.

Yeah, I think keeping the weight back is the difference-maker. I was self-taught and had been riding for years before someone mentioned that if I didn’t get my weight back I was going to go over the bars. I was like, yes, I’ve done that.

[ginacico]

Avid BB7’s still function in C&O Canal mud. (This was about 15 miles after a squirt-bottle bath.)

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[mstone]

@huskerdont 160797 wrote:

I just wonder that since the rear brake doesn’t do as well anyway, that’s where there should be more power to compensate. But I suppose if that extra power were to make the tire lock, that would be counterproductive.

Bingo. It doesn’t take much to lock a rear brake, so making it bigger is pointless–all you’ll do is skid and/or lose control.

[mstone]

So I actually pondered going road hydraulic for my planned rebuild of my do-everything bike. (It needs new rings & cassette & cables & whatnot anyway, so why not take it from 8 gears to 10 and address every other possible want at the same time?) So I’m pouring over the shimano tech docs (have I ever mentioned how much I hate shimano?) and it seems like there’s a total dumpster fire right now. So shimano invented a new standard for brake mounts? And, being shimano, they even have different pads for brakes within the same family with different mounts? And the only 10 speed hydraulic shifters are mechanically incompatible with everything other than the current 11 speed (road) stuff. It’s like evil gnomes sit around a table at shimano hq discussing how to prevent people from building the bike they want. I think I’ll stick with 5700 shifters and try the hy/rd brakes rather than buying into this mess.

[Author]

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