Caliper

It's not magical, simply math. If you have those 19mm rims with 23mm tires, the caliper release only has to open up by 4mm for the pads to clear the tire, super easy. Put 32mm tires on the rim and now the release has to open up 13mm for the pads to clear and you may have an issue. But, if you have a 23mm rim, the pads are further apart to begin with and now only have to open up 9mm to clear a 32mm tire.

Honestly, everyone claiming that caliper brakes can't clear 32mm tires is a bit silly considering that some decades ago the most commonly sold road bikes in the US used 27x1.25" tires, which typically measure 30-32mm and they usually ran caliper brakes. Nobody had any issues removing wheels then. Go back further to the original 700C tire and you'll find those were approx 40mm tires. The "need" to run discs for wider tires on road bikes is created by marketing.

Personally, I'm running a 37mm tire on a 25mm (external) rim on such a steel road bike. I like to keep my pads close to the rim so the calipers are at their limit to clear the tire on release but removing the front takes nothing more than working the release mechanism.

tomato coupe

With many rim brakes, the issue is the lack of height rather than the limited amount of opening.

Caliper

Some are resistant due to steady issues with discs and no better performance in dry (which is 99% of my rides). I have three disc equipped bikes and only one of them is consistently quiet when braking. The other two will intermittently squeal and screech when braking depending on the weather or the phase of the moon or whatever. That has made me fuming mad by the end of some rides. There is also the tendency of the rotors to occasionally go out of true for no reason. Two of these bikes rarely even have the wheel removed - typically ridden from home. I have literally not touched anything but the brake never, not removed a wheel, but there's a little scraping suddenly and I have to go and realign the caliper. One of these bikes is a through axle even. My hydraulic brakes also have more free play in the lever than I want. On mech discs, I can tune this out so that they engage quickly but hydraulics have too much gap to take up and this isn't adjustable so the feeling of sloppy brakes is a bit irritating.

Caliper

Considering that the mounting bolt for caliper brakes is only a mm or two above the peak of the caliper frame, if your tire is hitting the caliper it is also likely to have clearance issues with the frame regardless of the brakes you have. Again, not an issue with the mechanism, but a design issue chosen by equipment companies who used to make bikes and caliper brakes that would clear 40mm tires...

Steve B.

Ah, Yes, that makes perfect sense. I had forgotten the need to reset brake position for wider rims, which I’m (unfortunately) not running on my Soma. It’s still old school 19mm wide road rims with 28mm tires, which are plenty wide for local conditions.

Dave Mayer

On my 'cross bike with rim brakes I can easily clear 32mm tires. This bike is fitted with TRP 8.4 mini-V's that have incredible power and modulation.

On my old MTB, I have 55mm knobbies and XTR V-brakes. Again, incredible brakes.

So I don't buy the argument that discs exist to facilitate bigger tires. Besides, I know, we're all getting fatter, and so we need fatter tires, but I don't see the need for road tires >28mm, even when navigating the crappy chip seal on the tarmac in Alaska.

Steve B.

Not sure anybody stated or meant that discs “exist” for bigger tires, just that do facilitate the use of larger tires as compared to standard dual pivot or direct mount road brakes. V’s and cantis are a different story but they’re not generally used on “road” bikes and are falling out of use on touring and cross, if not gone altogether in the middle to upper price ranges. I’m certain the move to disc is in all cases driven by the adoption by mt. bikes almost exclusively and for better or worse.

One thing I find a positive in the industry is gravel bikes whose geometry is not a racing cross bike, yet that allows use of pretty big tires, 37-40 or greater. Or you do a second set of wheels and run 28’s (or 25’s if you like). You can do this on frames with V or canti, but as many 700c equipped bikes were heavy touring bikes, the gravel bike now dumps a lot of weight, 4-5 lbs or so and that’s not even in a carbon. Thus you can buy 1 bike, 2 sets of wheels and get a lot of functionality out of a not too heavy bike.

jadocs

Ha I was thinking the exact same thing.

FLYBYU

As a bigger guy (250lbs) I appreciate disc brakes for their stopping power. I recently bought an old road bike with rim brakes and it is astounding how horrible the rim brakes are. My V-brakes on my old mountain bike are also not the greatest for sustained use, but stop me fine in an emergency situation. If I buy a new bike at some point, it will have disc brakes, no question.

Atlas Shrugged

Just when I thought I was out . . . they pull me back in.

DaveSSS 

An old bike probably has old pads that need replacing and rims that need some cleaning and sanding. Discs are great for heavy riders and wet conditions. At 140 lbs. I don't need them on any Colorado mountain I've been down, even when hitting speeds up to 54 mph. I hit 48-54 mph on nearly every ride.

tomato coupe

Are you sure you don't mean 48-54 km/hr?

Steve B.

[QUOTE=tomato coupe;21221862]Are you sure you don't mean 48-54 km/hr?[/QUOTE

Not unlikely to have seen 50 mph out that way, I hit 54 on 2 occasions in New Mexico. Easy to get up to speed on the multi-mile downhills. I regularly saw 40 on many road rides. I have to really work to see 40 here on Long Island.

I also well recall wearing out a set of V brake pads on day 2 of the ‘99 Bike Tour Colorado while descending Coal Bank Pass. I only heard the sound as the pads were diving under the rims. Had to stop in the cold and rain to move the pads higher. Got into Durango and installed new pads. When disc brakes got popular I could look back and think how useful they would have been on a tour that saw rain every day for 7 days.

tomato coupe

"I hit 48-54 mph on nearly every ride."

Call me skeptical.

Caliper

Old pads suck because the pad material goes hard with time. Also, what brand are they? Cheapo pads started bad and only get worse. Get some Swiss Stop pads or something similar.

Koyote

Note that the poster's sig indicates that he/she is in Loveland, Colorado. Are you familiar with the area, @tomato coupe ? I lived right up the road in Fort Collins for many years, and my regular routes had me routinely hitting those speeds. One of my frequent routes went up Rist Canyon and then down into Buckhorn Canyon, and I would always hit 60+ mph on the descent into Buckhorn. And on the Horsetooth Reservoir Dam road I once hit (in a race) an indicated 75.7 mph.

Back on-topic: out where I live now (Western PA) the hills are shorter than in CO, but many are very steep; I hit 40 mph on almost every ride without even trying, and could hit 50+ mph pretty regularly if it weren't so dangerous - the hills are steep and short, and at the bottom of each one there is usually a crossroad at which I must yield. Disc brakes are wonderful, and they require no more maintenance than my rim brakes.

FLYBYU

They are quality pads (Shimano) but they are very old. I hadn't planned to ride it outside til spring (it has been on the trainer for two months already) but we had a few days of spring like weather so I couldn't resist some outdoor riding. I will have to try some better pads in the spring.

Gresp15C

Back then, there was rarely any reason to remove a wheel unless the tire was deflated.

tomato coupe

I have no doubts he hits those speeds, but not "on nearly every ride."

Koyote

Well, I'm sure you know more about the poster's riding than he does.

DrIsotope

If someone isn't exceeding 50mph on every single ride, they aren't doing their Bike Forums due diligence. I would be disappointed were people posting to the contrary.

tomato coupe

If someone always averages 25+ mph, does that absolve them of their responsibility to exceed 50 mph on every ride?

DrIsotope

Oh, absolutely. The only excuse to average under 25mph is to average +200ft/mi of ascent.

HTupolev

I don't understand why it's a hard claim to believe. I don't exceed 50mph on nearly every ride, but I could if I wanted to. I'd just need to start being preferential to hills that are easy to reach 50mph on, of which there are some local to me. Many people living near mountains have many such hills available.

Wilfred Laurier

I cruise at 48-54 mph on the flats, but I don't like going that fast on downhills because I don't want to overheat my brakes if I need to stop. I have no problem going 48 mph up hills, but I sometimes struggle to reach 54mph - I must need a bigger chainring.