7/13/14 5:09 PM

quote:

---

Linda and I have both gotten our MTB brakes so hot that they were smoking and the disks changed color, but they didn't fade and the disks remained true. For the record, this was on a ridiculously steep road descent in Point Reyes, CA.

---

7/13/14 5:10 PM

Does the fork on a road bike need to be overbuilt compared to rim brakes? If so, does this degrade the ride quality?

7/13/14 5:26 PM

Obviously people have different experiences. The hydraulic disks I on my bike have been a PITA. Shortly after I got the bike, they started screeching which became worse and worse until it was intolerable and I wouldn't ride the bike. I have heard this complaint from others as well. Even the LBS (who did not set the bike up in the first place) had a lot of trouble eliminating the squeak, a number of things needed to be replaced and it took quite a bit of time. There was also a leak, which was hard to find, which took the pressure on one lever down to practically nothing. Again it took awhile to fix permanently. And heaven forbid the rotors get grease or oil on them - replace. And wheel changes, while certainly doable, are cumbersome. I am the first to admit I am not a great mechanic, but I can adjust a canti or caliper.

OTOH, I have ridden for over 40 years, in all kinds of rain, snow and sleet, and I have never once felt that my caliper or canti brakes were inadequate.

Again, YMMV

7/13/14 6:13 PM

The Juicy Avids on my 29er Gary Fish are event free.
2 cents there...

7/13/14 7:41 PM

I've said this before, I will never go back to rim brakes for my winter/rain bike. Ever. No more wiping down black rims after every ride either.

The modulation and smooth braking power impress me every time I switch from road bike to my Dirty Disco w/mech disc brakes.

7/14/14 5:09 AM

The point was that disk brake rotors are unlikely to warp due to extreme use.

The road is question was probably the steepest piece of pavement I've ever ridden (other than a few short stretches) and the descent was at least a couple of miles. It was very twisty and required you to be on the brakes almost constantly. It was as much of a worst-case torture test for brakes as I've ever seen and not something that most people would ever encounter on the road. The fact that our brakes didn't experience problems WAS impressive to us, especially considering that MTB brakes are not designed for that type of riding. Had we be using rim brakes, I would have been concerned about melting brake pads and overheating rims.

7/14/14 5:23 AM

...as my experience has been predominantly positive. Squealing can obviously be an issue with some brakes, but from what I've seen, it's less so than it used to be. I've done some playing around with mixing organic and semi-metallic brake pads on one bike to improve the feel and reduce noise, and that worked well. I have yet to experience a leak of any kind and I suspect that they will be very rare on road bikes, since they don't suffer the level of abuse that MTBs do.

Contaminating rotors hasn't been much of an issue, either, since they're not close to anything that you need to lubricate. You're far more likely to drip chain lube on a rim (happens all the time) than to get anything on a rotor. Contaminated rotors can be cleaned with solvent and they'll work fine. Contaminated brake pads require replacement. I've only had that happen once and it was my fault for not removing the pads when bleeding the caliper after trimming the brake line on a new bike. Lesson learned.

7/14/14 9:56 AM

"The point was that disk brake rotors are unlikely to warp due to extreme use. "

Brian, I wasn't disagreeing with your point. I was just surprised at the condition of the disc brake in a stretch that's not particularly extreme by west coast standard.

I rode that part of the bay quite frequently when I used to live there. All I had were rim brakes. Yes, the rims typically got really hot to the touch in just about ANY of the significant local descends.

Page Mill, the south bay local favorite climb/descend, is longer, if not steeper, which everyone who's into climbing does regularly. Yes, everyone knows they shouldn't touch the rim, and a few people had the unpleasent experience of having their fingers (or thigh) tattooed when they forgot that. But I really didn't hear much talk about tires coming off the rim though. If the disc gets so hot it changes color, it would be even more hazardous to any unintentional contact!

I'm not sure I would go so far to say disc brakes are "not designed for such use". I can think of a bunch of mountain bike trails & fire roads that are just as long and steeper. I'm incline to think the concern about disc brake over-heating is probably a bit over-stated? Granted, the disc will get hotter than rims, due to the far smaller surface area. But as long as they continue to perform, as Brian observed, that's all it matters.

7/14/14 10:03 AM

In my case some junk got burned into the rotors at which point they were shot. I did have some of the Finish Line stuff that is supposed to clean/quiet the brakes, but that didn't touch the squeak.

I don't doubt that most disks work fine, maybe I got a bad set or bad setup or the planets were aligned wrong. But whatever problems I might have had with cantis, they would have been much easier to fix. So I just felt I was getting a lot of crap for hypothetical "advantages" I didn't need. If the brakes had always worked like they do now, I'd have said fine.

7/14/14 12:40 PM

...that we rode up Sir Francis Drake Blvd, climbed up a long, steep fire road to the ridge on the west side of Tomales Bay, rode the ridge trail, then came down on a steep, twisty paved road.

I'm curious about what got burned into Dan's rotors. I have cleaned rotors with sandpaper and/or Scotchbrite to remove surface contaminants and they were fine afterward. Then again, I do a lot of things that shops probably wouldn't, in the name of being a frugal Yankee. ;-)

You can also clean rotors with any residue-free solvent or with water, for that matter. Automotive brake cleaner works well (imagine that!?). I tried using it on pads contaminated with brake fluid, but no dice. I also tried burning it off, but that really didn't work either. It was worth the try, if only for the experience.

7/14/14 4:11 PM

Y'all highlight yet another issue. They are finicky about being kept clean and even more of a pain than you are willing to admit to yourselves.

Thanks, but no thanks on my road bike.

7/14/14 7:10 PM

Obviously the forks on disc-equipped bikes need stronger legs to combat the tendency for the caliper to flex the left leg and thus steer the wheel toward the left.

So the usual fork flex that most framesets are designed to have must be reduced for disc-compatibility.

I twice had tires blow off of hooked-bead rims (once while riding in the L.A. area and once down Page Mill) at the bottom right-hand curve. Heat was definitely a factor on both occasions, but hooked-bead rims weren't then quite what they are today.

For persistent disc-brake squeal, changing to a rotor with a different pattern of cutouts may help greatly.

7/14/14 10:52 PM

While descending a hill at Wintergreen resort I had a double failure of both tubes that superheated due to rim friction...thankfully no crash but things got sporty real fast.
+1 for disc brakes

7/15/14 5:58 AM

Disk brakes are no more sensitive to contamination than rim brakes are.

You've obviously made up your mind that you don't like or want disk brakes. Fine, nobody is going to force you to use them, so you don't have to justify your choice though exaggeration.

7/15/14 6:57 AM

But I have to admit that for a tourist or commuter, certainly, they have their place.

I was riding to the office this morning after a powerful rainfall last night. Water and grit everywhere (a good test for the bottom bracket dynamo I'm testing!), and before long, grit on the rims and pads. There's some cleaning to be done when I get home.

Discs are far enough away from (most) puddles and (most) grit not to suffer that kind of contamination--what's more, if they do suffer contamination, you're not at risk of damaging your rim.

At the same time, I just think they're ugly on a road bike...in my opinion (and that's all it is) they turn something graceful into something more machine-like.

7/15/14 7:21 AM

I believe the jury is still out on disc for road bikes. For MTBs they are already nearly standard and CX bikes seem to be headed that way.

For pure road bikes, particularly race bikes, the designs will have to be refined to overcome the current weight, aero and wheel change disadvantages. We are still in the early stages of disc brake design so these may very well be manageable.

At this point i have no incentive to buy a road bike that uses them but in the future, who knows?

7/15/14 7:50 AM

"For pure road bikes, particularly race bikes, the designs will have to be refined to overcome the current weight, aero and wheel change disadvantages."

That's my experience too. Every time I took the front wheel off for transport, it's lottery time whether it'll go back fine or it squeal like a pig! For the mtn bike, we ended up buying a upright carrier tray for it so we didn't have to take the wheel off for transport. Talk about expensive!

I'm not willing to carry my road bike outside. In the trunk is where it belongs. So until the wheel change can be made flawless like in the case of rim brake, I'm not taking the bait.

Disc isn't without it's disadvantage. But its advantage on mtn bike is so significant that we're more than happy to put up with those disadvantages. On road bike, the advantage is much smaller so most of us are quite unwilling to put up with the disadvantages.

7/15/14 10:56 AM

I had a similar problem with one set of wheels on my old MTB. The axle end was not perfectly round, so it would shift the wheel position slightly, depending on what part of the axle was against the dropouts. I ended up making a mark on the end cap that I could align upward, so the wheel was always in the same orientation. Five seconds with a Sharpie and problem solved. I haven't had that issue with any other set of wheels on either of my disk-equipped MTBs.
This can also happen if you get mud buildup on the axle end, but that's just a wipe it off and go situation.

My 29er has a through axle in the front, which eliminates any alignment issues at the source. That's another technology that will probably be making it's way onto road bikes in the near future, as it's already showing up on 'cross and gravel bikes. It shows a lot of promise vs. standard quick releases:

- It stiffens the fork laterally and torsionally, without affecting vertical compliance. This is positive for any use.

- It eliminates issues with "lawyer lips" on forks. This has become an obvious problem for racing, as evidenced by the ridiculously slow wheel changes you see in pro races now, since they're not allowed to file them off anymore.

- With the new designs that require only a 90 turn to disengage and retain the axle in the left dropout, wheel changes are easy and fast.

- It eliminate any possibility of a wheel being ejected from the dropout.

- The weight difference vs. a Q/R minimal.

As with disk brakes, it will take some time for the products to evolve and standards to be established, but it will happen.

Last edited by Brian Nystrom on 7/15/14 2:21 PM; edited 2 times in total

7/15/14 11:23 AM

I prefer the through axle myself. Especially if the front wheel is coming off more often, like transporting etc.

Another reason I like the bike rack with the wheel loops. We got that mainly due to not wanting to hang the carbon bikes from the top tubes, but have come to like it for additional reasons. Not least of which is less scratches...

7/15/14 2:24 PM

...I won't buy a vehicle that won't carry at least two bikes inside . It never made sense to me to hang thousands of dollars worth of bikes on the outside where they're exposed to the elements, road hazards and theft.

7/15/14 2:38 PM

"It never made sense to me to hang thousands of dollars worth of bikes on the outside where they're exposed to the elements, road hazards and theft."

Well to rebut that. If it is nice enough to take a nice bike out via car/rack... It is nice enough to stay clean on the rack. If it is shitty enough for a bike I would use in shitty weather, I hope the rain on the return gets it 1/2 clean on the way home. Because I am going to have to clean it when I get home. i am pretty fussy about when the Scott goes out, and the Paramount too.

As to theft, a cable locks my bikes to the rack when appropriate. As far as unattended, the can bust a window out just as easy. So when the bike are in the Equinox, they still get cable locked if i need to leave unattended, and covered so they are not obvious. But I had a friend's PX-10 30 years ago get pulled out of his van after a smash and grab when it was parked. Cable lock

That said, a doctor where Elaine worked had to testify in court when he had a guy at a light grab his Cervelo off the rack and try to take off with it.
A cable and lock would have probably made this a non event [as it would not have happened most likely]. It did not end well for the thief in that case, but I get the point.

But since Elaine's car [still in body shop] got that $10k hit, I do think more on a rear end bike smashing event honestly.

Yada yada

7/16/14 7:05 AM

most OEM rotors are a single sheet of steel, the perfect form to resonate and squeel.

2-piece rotors generally have a stiffer aluminum carrier along with the riveted interface between the rotor and carrier. instead of 1 big homogenous plane of metal that's just waiting to harmonize and shriek, it's a stiff & somewhat complex structure that change the harmonics in a meaningful way to minimize squeal.

<img src="http://i.ebayimg.com/00/s/NzU2WDU2Nw==/z/ZBoAAOSw8lBToSEn/$_12.JPG">

but the stiffer carrier also makes them tougher to true, so the mfg has to have tight production QC -- which apparently is where SRAM falls on their face. i have a sram XX 2-piece rotor and it has a slight sine wave that has proven well nigh impossible to remove! i fitted up a 1-piece avid rotor for grins, and while it was also out of true i was able to get it super-straight in a couple minutes.

7/16/14 8:07 AM

Newsflash, brake can squeal. ;)

7/16/14 10:22 AM

I just saw a review of the 2015 Giant Defy, a Roubaix-style bike that integrates disc brakes into an ultralight frameset.

The bike overall makes disc brakes look at least better to my eye, though they stuck with standard QR axles because of a delay in manufacturers settling on what the new "standard" for hub axles will be.

The top model uses electric Dura Ace and sells for I believe 10,500.
It integrates a flexing seat tube junction that uses no moving parts or visible gimmickry beyond the designed-in, localized structural flex, and hits high benchmarks for specific flex and stiffness characteristics.

7/16/14 11:44 AM

They show this and talk about the bike having wonderful clearance:



But apparently forget this part:



I doubt the tires shown are >25mm

(Sorry about the photo sizes).