Rim brakes + fenders = oxymoron

[jpw]

in this dawning epoch of disc road bikes is the traditional rim brake plus fender mounting frame and fork oxy?

[christian]

No. Every 57mm rim brake is presently better than every road disc brake.

[John H.]

Yes- disc brakes would give more clearance at the fork and rear brake bridge but discs have issues of their own.
Also, there are not a bunch of good forks out there for this.
The disc movement is more about the bike industry wanting to sell more bikes.
I have always said that ability to brake is not the limiting factor in wet weather- tire traction comes into play 1st.
Discs do not help with tire traction.

[dustyrider]

8.99" of annual rain, here fenders=oxymoron. :)

[mossman]

what do fenders have to do with discs? are you familiar with the definition of oxymoron?

[jpw]

what do fenders have to do with discs? are you familiar with the definition of oxymoron?

enlighten me

[parris]

It could be how some fender brands aren't friendly with some frame//brake combinations. I picked up a pair of Planet bike road bike fenders and the plastic brake bridge bracket was too thick to for the brake tire combo. I called their cs number and they ended up sending me the thin metal bracket that use to be common with several fender brands. I'm not saying this is the only reason just that it could be a reason.

[Grant McLean]

what do fenders have to do with discs?

They both are purportedly beneficial in wet weather.

-g

[bcm119]

I don't think the combination of 57mm caliper brakes, fenders, and 28mm tires will be surpassed anytime soon for a rain bike setup. Discs dont make any sense to me, from a physics standpoint. Far more force required to stop a wheel by clamping it 6" from its axis than at the edge of the wheel, far more heat build up, and far more forces transferred to (one) fork leg and seat stay. They may feel great but part of the appeal of bicycles for me is their simplicity, and discs are a step backward in that category.

[fiataccompli]

Not completely sure the meaning of the original post but thought I would add this tangential data point: I have a Kona Honky Inc. ...figured it would be interesting to check out road discs, good utility road bike, etc...mounting fenders (full, with stays) while accounting for the brake hardware was a minor challenge...I only say that because it seemed surprising since you would think a bike like that with disc brakes would be made to be very simple for fenders....for whatever that's worth (probably not much, I know...)

[KidWok]

Not completely sure the meaning of the original post but thought I would add this tangential data point: I have a Kona Honky Inc. ...figured it would be interesting to check out road discs, good utility road bike, etc...mounting fenders (full, with stays) while accounting for the brake hardware was a minor challenge...I only say that because it seemed surprising since you would think a bike like that with disc brakes would be made to be very simple for fenders....for whatever that's worth (probably not much, I know...)

Before getting bikes that mount the brakes to chain stays, I used to bend the head of the strut loop 90 degrees and attach it to the M6 bolt that attached the calipers to the adapters. Sometimes, that required getting a longer M6 in order to make sure there were enough threads in the adapter. This was a lot cleaner and more reliable than using a long spacer at the dropout eyelet.

http://i27.photobucket.com/albums/c151/TaiLee77/Bikes/IMGP1733.jpg

Tai

[jpw]

when it rains rim brakes are poor, and so what's the logic of offering fender mounts on frames and forks designed for rim brakes?

discs work well in the wet.

[Bruce K]

Oxymoron - two disparate or opposite words used together to create a dramatic effect

Jumbo shrimp
Random order
Growing smaller

BK

[soulspinner]

i don't think the combination of 57mm caliper brakes, fenders, and 28mm tires will be surpassed anytime soon for a rain bike setup. Discs dont make any sense to me, from a physics standpoint. Far more force required to stop a wheel by clamping it 6" from its axis than at the edge of the wheel, far more heat build up, and far more forces transferred to (one) fork leg and seat stay. They may feel great but part of the appeal of bicycles for me is their simplicity, and discs are a step backward in that category.

+1

[christian]

when it rains rim brakes are poor, and so what's the logic of offering fender mounts on frames and forks designed for rim brakes?

discs work well in the wet.Good rim brakes work more than adequately in the wet. Discs tend to get less water/grit contamination, but whn they do, it' worse than rim brakes. Other than accelerate rim wear, I'd say rim brakes are at least as good.

I think the more fundamental question is, "Is there any good reason for disc brakes on road bikes at all?"

[saab2000]

There is a bike in my future which will use disc brakes. It will also have fender mounts.

My Hampsten single-speed has rim brakes and fenders.

I expect both will work fine and the fenders will keep me clean and dry when I ride in wet weather. :D

[Bruce K]

The only times I have ever even thought about discs for a road bike was on long, fast, mountain descents where taking away the possibility of overheating the rim/tire combination was beginning to worry me.

I know about modulating the brakes and have never has a heat related failure but the added confidence a disc would provide might be nice if I was regularly in that environment.

But at this time there are no on road disc brake bikes in my future

BK

[saab2000]

I was the lucky winner of a raffle involving Independent Fabrication. I'm getting a gravel road bike which will have discs and I'm going to use whatever is the best cable-actuated brake I can find when the time comes to build it up. TRP makes a hydraulic brake where the hydraulics are at the caliper but a cable actuates it. I will do this because I am not interested in the current crop of road levers with hydraulic master cylinders. Today this is limited to Sram and the new Ultegra Di2 hydraulic.

We'll see how it works. It's definitely a bit of an experiment with some unknowns.

It seems many folks who like discs have them and others who condemn them don't have them. I simply don't know the answer but I will find out! :beer:

[christian]

The only times I have ever even thought about discs for a road bike was on long, fast, mountain descents where taking away the possibility of overheating the rim/tire combination was beginning to worry me.Overheating discs is a much, much more likely scenario. Boil off some hydraulic fluid for real excitement!

[christian]

I was the lucky winner of a raffle involving Independent Fabrication. Saab, this bike will be cool, but why not go with Ultegra Di2 hydraulic. It's bound to be the only system to work worth a damn. Yeah, the cost isn't ideal...

[oldpotatoe]

Saab, this bike will be cool, but why not go with Ultegra Di2 hydraulic. It's bound to be the only system to work worth a damn. Yeah, the cost isn't ideal...

Hmmm, gravel road bike..I think his choice is a good one, mechanical discs, even those that are cable to wet hydros. I think there are great applications for discs..like wet weather commuter, gravel bikes, places where discs offer advantages, just like they do in MTBs...wet, muddy, crappy riding, high probability of wacking a rim and still be able to ride.


For those 'enthusiats' bikes, the carbon wunderbikes used for those dry,sunny, weekend jaunts with the others from the coffee shop..don't see it as a 'need'. But will some get the latest and greatest, carbon, wet hydros, zillion $ wheels?...yep, for good or ill.

[happycampyer]

I think the more fundamental question is, "Is there any good reason for disc brakes on road bikes at all?"After Saturday, all I can say is that, on certain sections where I really wanted brakes, I much preferred the braking of the Moots with discs over the Hampsten with mid-reach brakes. I'm going to see if Justin will let me borrow his bike so I can do a three-way comparison on some local dirt roads, etc. On paper, at least, his bike seems to solve things I dislike about the Moots and the Hampsten. I'd probably wait for hydraulic Di2, based on discussions with Justin.

[saab2000]

Saab, this bike will be cool, but why not go with Ultegra Di2 hydraulic. It's bound to be the only system to work worth a damn. Yeah, the cost isn't ideal...

The cost won't be ideal either way I do it.... the main reason I'm not going Di2 is that it doesn't stir mg soul. At all. I like the feel of mechanical shifting.

I may go Shimano on this build. For a huge change for me.

Longer stays, more clearance everywhere, different (more stable) geo in the front. Looking forward to it. I never felt 100% comfortable on the loose gravel descents on my regular road bike.

[benb]

Why is this forum opposed to any excuse to play bike consumer? Sometimes their is a lot of cognitive dissonance between what people are saying and their constant buying of new bikes.

It's probably not a good idea to assume road discs suck until you've tried them and they've been sorted out. Pretty much anyone who would claim they suck on MTB I'd laugh in their face, maybe they are not fully sorted yet for road but when they are they will be better, it won't even be close.

[christian]

maybe they are not fully sorted yet for road
Maybe? And the heat dissipation requirements for road are vastly higher than for dirt. Hydraulic road disk brakes will be very good one day, and Shimano will lead the way. But that day is not today.*

(*Please note that this does not apply to Happycampyer. I'm totally fine with Happy discarding his hopeless vintage-era mid-reach caliper SBTi for a hydraulic disc Seven!)

[BCS]

Why is this forum opposed to any excuse to play bike consumer? Sometimes their is a lot of cognitive dissonance between what people are saying and their constant buying of new bikes.

It's probably not a good idea to assume road discs suck until you've tried them and they've been sorted out. Pretty much anyone who would claim they suck on MTB I'd laugh in their face, maybe they are not fully sorted yet for road but when they are they will be better, it won't even be close.

^^^This. There are still some who believe bibs and full zippers are marketing ploys. New does not always suck.

[false_Aest]

I think the more fundamental question is, "Is there any good reason for disc brakes on road bikes at all?"

Sounds like something the UCI would say.... minus the BS about something not proven to be safe.

Also sounds like something I heard when Shimano offered 10 speed + Campy offered 11.

[jpw]

I was the lucky winner of a raffle involving Independent Fabrication. I'm getting a gravel road bike which will have discs and I'm going to use whatever is the best cable-actuated brake I can find when the time comes to build it up. TRP makes a hydraulic brake where the hydraulics are at the caliper but a cable actuates it. I will do this because I am not interested in the current crop of road levers with hydraulic master cylinders. Today this is limited to Sram and the new Ultegra Di2 hydraulic.

We'll see how it works. It's definitely a bit of an experiment with some unknowns.

It seems many folks who like discs have them and others who condemn them don't have them. I simply don't know the answer but I will find out! :beer:

congratulations on your good luck. envy.

why are road levers with master cylinders of no interest?

[jpw]

After Saturday, all I can say is that, on certain sections where I really wanted brakes, I much preferred the braking of the Moots with discs over the Hampsten with mid-reach brakes. I'm going to see if Justin will let me borrow his bike so I can do a three-way comparison on some local dirt roads, etc. On paper, at least, his bike seems to solve things I dislike about the Moots and the Hampsten. I'd probably wait for hydraulic Di2, based on discussions with Justin.

hydro Di2 is coming out around November time i think. not long to wait.

what do you dislike about your Moots?

[christian]

Sounds like something the UCI would say.... minus the BS about something not proven to be safe.

Also sounds like something I heard when Shimano offered 10 speed + Campy offered 11.Nonsense, I'm not opposed to disk brakes at all -- I'm opposed to their current implementation. My motorcycles have hydraulic disk brakes, and they work great.

But a cable-actuated BB7 operating on a 160mm rotor would NOT be my first, second, or third choice today for riding down the east side of the Fedaia or the Hochalpstrasse from Hochtor to the Zoo.

When Shimano brings out a 180 or 205mm-rotored, hydraulic road disk brake with Di2 shifting, I'm sure it'll be great, though still heavier and requiring heavier wheels than a rim brake solution. That's a solution I'd happily ride.

That doesn't exist TODAY. So if you're building a bike today, you could either (a) build it with mediocre cable disks and make sure it has all the provisions for hydraulic groups with a plan to swap to hydraulic Di2 Ultegra asap (what Happy and my friend Justin did) or (b) build it with mid-reach calipers.

[jpw]

...and now there are these;

http://www.zipp.com/wheels/303-firecrest---carbon-clincher-disc-brake/

[jpw]

Nonsense, I'm not opposed to disk brakes at all -- I'm opposed to their current implementation. My motorcycles have hydraulic disk brakes, and they work great.

But a cable-actuated BB7 operating on a 160mm rotor would NOT be my first, second, or third choice today for riding down the east side of the Fedaia or the Hochalpstrasse from Hochtor to the Zoo.

When Shimano brings out a 180 or 205mm-rotored, hydraulic road disk brake with Di2 shifting, I'm sure it'll be great, though still heavier and requiring heavier wheels than a rim brake solution. That's a solution I'd happily ride.

That doesn't exist TODAY. So if you're building a bike today, you could either (a) build it with mediocre cable disks and make sure it has all the provisions for hydraulic groups with a plan to swap to hydraulic Di2 Ultegra asap (what Happy and my friend Justin did) or (b) build it with mid-reach calipers.

i've been riding on bb7 and a 160mm rotor. not so bad. i don't like that only one pad moves to the disc. hydro improves on this obvious flaw.

[saab2000]

congratulations on your good luck. envy.

why are road levers with master cylinders of no interest?

Thanks!

They would possibly be of interest but I have no real interest in Sram components. I'm sure it works well for many people but even going Shimano is a leap for me. I've been a Campagnolo rider for a long, long time and I might make the leap to Shimano for this bike. If so, I'm probably going DA9000 but might go Ultegra as it seems like DA=XTR and Ultegra=XT and XT is the go-to stuff for a lot of serious mountain bike folks.

As to the Shimano with the master cylinder, well, I'm not really interested in Di2. I know it works great and all that but I prefer the mechanical shifting feel. That's really all.

If there were a Shimano mechanical group with a hydraulic disc brake I'd probably do that.

I had a 3-4 hour ride this summer on Shimano and I really enjoyed it. It was my first ever real ride on it. I had tried it in work stands and around parking lots, etc. but never on a real ride using the whole range of gears. In addition to flawless shifting, I liked the ergonomics of the shifters much more than I thought I would.

[jpw]

Thanks!

They would possibly be of interest but I have no real interest in Sram components. I'm sure it works well for many people but even going Shimano is a leap for me. I've been a Campagnolo rider for a long, long time and I might make the leap to Shimano for this bike. If so, I'm probably going DA9000 but might go Ultegra as it seems like DA=XTR and Ultegra=XT and XT is the go-to stuff for a lot of serious mountain bike folks.

As to the Shimano with the master cylinder, well, I'm not really interested in Di2. I know it works great and all that but I prefer the mechanical shifting feel. That's really all.

If there were a Shimano mechanical group with a hydraulic disc brake I'd probably do that.


I had a 3-4 hour ride this summer on Shimano and I really enjoyed it. It was my first ever real ride on it. I had tried it in work stands and around parking lots, etc. but never on a real ride using the whole range of gears. In addition to flawless shifting, I liked the ergonomics of the shifters much more than I thought I would.

interesting view of things. thanks.

i prefer the styling of Campagnolo, and the lines of EPS mechs are more pleasing than Di2.


"Hochalpstrasse" - that sounds rather steep.

[saab2000]

"Hochalpstrasse" - that sounds rather steep.

Not necessarily steep, but certainly possible!

My experience living in Switzerland was that some of the steepest climbs I ever encountered were not the highest ones. There were some 2-3 km climbs in the lower hills (still a couple thousand feet high thought) that were killer steep. As in almost-have-to get-off-your-bike-and-walk steep. :eek:

[benb]

IMO road is not going need a rotor bigger than 160mm for a "single" bike with your typical competitive cyclist weight... but cable operated might be an issue.

I've done lots of these little 2-3km descents that average > 10% grade and have 20%+ sections and they completely destroy road rim brake systems. Absolutely no issues at all in any weather with my MTB with 160mm hydraulic discs.

I totally agree with this statement that a lot of the steepest and most technical paved roads are not on the longest/highest climbs. The longest/highest climbs tend to have the "engineered roads" that keep the grades & curves safer for big cars and semi trucks, a lot of the shorter ones are not navigable by trucks.

Personally I profoundly disagree with the idea that paved road riding has higher heat dissipation requirements than mountain biking. Not cross, not gravel dirt bike riding, I mean real mountain biking where even flatland trails have >20% descents with rocks & logs and stuff in the middle of them.. Go up to something like a ski area descent and you're on a completely different planet than road biking.

[christian]

Neglecting drag and other losses outside the brakes, the brakes’ retardation power is given by the negative of the time derivative of the cyclist/bicycle system's kinetic energy.

Because mtb speeds are so much lower, there is much less KE. WC DH might be the only exception - and, surprise, they use 200mm+ rotors.

[christian]

After Saturday, all I can say is that, on certain sections where I really wanted brakes, I much preferred the braking of the Moots with discs over the Hampsten with mid-reach brakes.

Goes to show, de gustibus non disputandum est. I much prefer the feel of Shimano R600s (which I had on my Rambouillet) to BB7s (which I have on my Cannondale). The _only_ benefit I feel BB7s have is that they require slightly less lever pressure.

That said, I had no issue with cantis on Hawks Road, either.

[jpw]

I much prefer the feel of Shimano R600s (which I had on my Rambouillet) to BB7s (which I have on my Cannondale). The _only_ benefit I feel BB7s have is that they require slightly less lever pressure.



even when raining?

[christian]

even when raining?

In rain on the road, yes. In mucky, sloppy, cx-style mud, no. But in the latter situation, I don't run fenders, either.

Even riding in the rain reasonably frequently, I still get 3-4 seasons out of a set of Open Pro/Nemesis/Reflexes before the rims go.

[BCS]

Goes to show, de gustibus non disputandum est. I much prefer the feel of Shimano R600s (which I had on my Rambouillet) to BB7s (which I have on my Cannondale). The _only_ benefit I feel BB7s have is that they require slightly less lever pressure.

That said, I had no issue with cantis on Hawks Road, either.

I used shimano r600 brakes on a Rambouillet with fenders during the very rainy PBP of 2007. Horrendous. I am still scared/scarred.

[happycampyer]

Goes to show, de gustibus non disputandum est. I much prefer the feel of Shimano R600s (which I had on my Rambouillet) to BB7s (which I have on my Cannondale). The _only_ benefit I feel BB7s have is that they require slightly less lever pressure.

That said, I had no issue with cantis on Hawks Road, either.So true. The first two times I rode D2R2, it was on a cross bike with cantis and Michelin Jets, and my only concern was braking modulation on the long, gravel descents. The Hampsten with caliper brakes and Jack Browns was a night-and-day improvement, and the Psychlo-X with discs better still (but incrementally so). This year was the first year that I actually didn't mind descending Hawkes (twice, no less!). Of course, others bomb past me on road bikes with 23 mm tires, so it's clearly a question of one's capabilities and comfort level...

To jpw, the Moots was a bit of an experiment. I picked up a Psychlo-X YBB disc in the classifieds—it's a little short for me, and it weighs a good 4 lbs more than the Hampsten.* It's also a few years old and was built with 130 mm rear spacing, which limits wheel choices, etc. It's still an excellent bike, but I think I can improve upon it for my particular purposes.

* Without getting into the weight-doesn't-matter debate, if I can avoid carrying an extra 4 lbs up the 7,000 ft of elevation for the 100 km route of D2R2 (or more if I ever decide to do a longer route), I'm all for it.

[jpw]

I used these brakes on a Rambouillet with fenders during the very rainy PBP of 2007. Horrendous. I am still scared/scarred.

which brakes?

[BCS]

which brakes?

shimano r600 (rim brakes)

[christian]

I used shimano r600 brakes on a Rambouillet with fenders during the very rainy PBP of 2007. Horrendous. I am still scared/scarred.Interesting. Kool Stop salmon-colored pads? What rims? I have found the r600 brakes to be absolutely great in the dry, in the rain, on a train, wearing socks, dodging a fox.

[jpw]

shimano r600 (rim brakes)

yes. rim brakes plus rain equal scary.

builders offering rim brake frames and forks with fender mounts are encouraging poor riding choices.

[BCS]

Interesting. Kool Stop salmon-colored pads? What rims? I have found the r600 brakes to be absolutely great in the dry, in the rain, on a train, wearing socks, dodging a fox.

open pro rims. ? pads

[jpw]

In rain on the road, yes. In mucky, sloppy, cx-style mud, no. But in the latter situation, I don't run fenders, either.

Even riding in the rain reasonably frequently, I still get 3-4 seasons out of a set of Open Pro/Nemesis/Reflexes before the rims go.

i've ridden with ceramic rims and good caliper/ pad combos in the rain and it's still poor. never rim brakes plus rain again.

[KidWok]

So true. The first two times I rode D2R2, it was on a cross bike with cantis and Michelin Jets, and my only concern was braking modulation on the long, gravel descents. The Hampsten with caliper brakes and Jack Browns was a night-and-day improvement, and the Psychlo-X with discs better still (but incrementally so).

Been riding BB7 and Shimano's BR-R505 since 2007. Definitely agree with this assessment of braking performance. I'd take long-reach dual-pivot calipers over canti's any day of the week. The difference between dual-pivot and discs is less notable. What I do like about disc brakes is that they have much less initial bite and the modulation curve is very gradual. Beyond that, they have the advantage of much less rim wear, especially if you ride daily in wet conditions. Performance-wise, I'm perfectly happy with dual-pivot and salmon-colored pads on alum rims in the rain. If things start sounding gritty, I usually squirt a bit of water onto the calipers and rims to rinse things off.

The difference for me is less about the brakes and more about the overall frame/fork performance. All other things being equal, a disc fork has to be more rigid and will give up some vertical compliance over a standard fork. With 32mm and up, I prefer disc. 28mm and lower, I'll still prefer to run standard dual-pivot brakes (either 49 or 57mm reach). At 28-32mm, you could go either way and if I could only have one, I'd lean towards disc brakes since I live in rainy Seattle. I wouldn't want disc brakes with tires 25mm and smaller...nor would I want canti's or mini-v's with 35's...and that is based off of experience and not hypothesis.

One of the issues I have is that it is a bit tougher to go back and forth between disc and non-disc brake bikes. Since they modulate differently, it always takes me a bit to remember how to use the brakes...kind of like switching between Campagnolo and Shimano brifters.

Tai

[christian]

builders offering rim brake frames and forks with fender mounts are encouraging poor riding choices.

i've ridden with ceramic rims and good caliper/ pad combos in the rain and it's still poor. never rim brakes plus rain again.
You clearly have your position well staked out, but I think these are pretty much the silliest categorical statements I've heard. We'll clearly have to agree to disagree.

BTW, under your edict, aren't frames with rim brakes categorically encouraging bad riding choices? It is possible to ride a bike without fender mounts in the rain. I've done it.

[John H.]

Let me preference this by saying that I ride a bunch in the rain (when it rains)- I do not resort to an indoor trainer.
I do have a full time fender bike. It does have rim brakes (it is awesome).
Yes, rim brakes don't grab as well in the rain. But they are still predictable (you must predict that they will not grab as strong).
Also, tire traction is way down over dry conditions.
As long as you know that and ride accordingly, it is all good.
Hard to blame the equipment unless you go out with too much tire pressure or worn out brake pads- rider is to blame if he over-rides for the conditions.

[PJN]

John H. wins.

The argument and best rain bike ever.

[jblande]

John H. wins.

The argument and best rain bike ever.

no joke.

[jpw]

You clearly have your position well staked out, but I think these are pretty much the silliest categorical statements I've heard. We'll clearly have to agree to disagree.

BTW, under your edict, aren't frames with rim brakes categorically encouraging bad riding choices? It is possible to ride a bike without fender mounts in the rain. I've done it.

i just think that frames and forks with mounting points are positively encouraging rims in the rain. the inexperienced will gain experience...but at what cost?

[ColonelJLloyd]

I think you are grossly overstating the issue and showing a clear bias because you like disc brakes. Rim brakes and fenders in the rain have been used for nearly a century with great results. They both have advantages/disadvantages. If you want to bet that discs are going to spell the demise of rim brakes I'll take take that bet.

[bcm119]

This isn't directed at anyone in particular, and may sound crazy, but in the rain I'd rather have less braking power than more. The argument that discs provide powerful stopping power even in rain doesn't interest me because the greatest danger rain poses (besides your visibility to cars) is tire grip. Even for experienced riders I think you generally have less traction in heavy rain than you think. A slight delay in grab on a wet rim can save you from sliding out in a quick stop situation, and of course on long descents you can pulse the brake to keep the rim dry and your speed under control.

[Mark McM]

IMO road is not going need a rotor bigger than 160mm for a "single" bike with your typical competitive cyclist weight... but cable operated might be an issue.

I wonder where the idea started that road bike discs can be smaller than MTB discs? If you look at the motorcycle world, you quickly see that road motorcycles use much bigger discs than off-road motorcycles. The reason is plain: Road motorcycles travel faster, and can brake harder, than off-road motorcycles. And the same is true for road bikes vs. MTB. If anything, a road bike should have bigger discs than an MTB.

[mtechnica]

wipe your rims down it isn't that hard :beer:

[KidWok]

The argument that discs provide powerful stopping power even in rain doesn't interest me because the greatest danger rain poses (besides your visibility to cars) is tire grip. Even for experienced riders I think you generally have less traction in heavy rain than you think. A slight delay in grab on a wet rim can save you from sliding out in a quick stop situation, and of course on long descents you can pulse the brake to keep the rim dry and your speed under control.

My experience with both avid and Shimano mechanical calipers is that they had less initial grab than rim brakes and ramp up more gradually, as opposed to my 7800's on alum rims that have a pretty big bite as soon as pads touch the rim.

Tai

[christian]

Shimano just issued a worldwide recall of every road disk brake they've ever manufactured.

http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/news_and_info/news/voluntary_recall_by.download.-mainParsys-0010-downloadFile.html/Web_Recall_EN_120813_RZ.pdf

[ColonelJLloyd]

Shimano just issued a worldwide recall of every road disk brake they've ever manufactured.

http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/news_and_info/news/voluntary_recall_by.download.-mainParsys-0010-downloadFile.html/Web_Recall_EN_120813_RZ.pdf

Oops.

[KidWok]

Shimano just issued a worldwide recall of every road disk brake they've ever manufactured.

http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/news_and_info/news/voluntary_recall_by.download.-mainParsys-0010-downloadFile.html/Web_Recall_EN_120813_RZ.pdf

Not every disc brake caliper they've ever manufactured...just the recent models. The BR-r505 is not included in the recall.

Tai

[benb]

I wonder where the idea started that road bike discs can be smaller than MTB discs? If you look at the motorcycle world, you quickly see that road motorcycles use much bigger discs than off-road motorcycles. The reason is plain: Road motorcycles travel faster, and can brake harder, than off-road motorcycles. And the same is true for road bikes vs. MTB. If anything, a road bike should have bigger discs than an MTB.

I don't have much dirt motorcycle experience but I used to do lots of street/track motorcycling. I don't think it's all that relevant to bicycles.

The reason street motorcycles have huge brakes is they have huge power. No matter where you are, you have enough power to have to brake hard for just about every corner if you're riding hard. (BTW, pretty much no street riding qualifies as "riding hard" if you're talking about a sportbike.)

IMO when you consider the generally steeper grades in the woods combined with much tighter corners MTB seems much closer to motorcycling. (And indeed it rewards more of the skills that can be ignored by road cyclists but are mandatory for a motorcyclist.)

Just graphing speed (a histogram of time in speed ranges?) for the different activities would be telling.. road motorcycling & MTB would have huge swings in speed, moto cross would probably be a bit more smooth, then moto trail riding is probably a bit smoother, and road cycling is probably the smoothest of all.

[Mark McM]

IIMO when you consider the generally steeper grades in the woods combined with much tighter corners MTB seems much closer to motorcycling. (And indeed it rewards more of the skills that can be ignored by road cyclists but are mandatory for a motorcyclist.)

I disagree. The speeds on road bikes are often higher, and road descents are often much longer than off-road, resulting in more heat dissipation on road bikes. As an example, consider the Avid BB series of brakes. These brakes are available in nearly identical MTB and road versions. Heat failures of the road versions are known to happen, but similar failures are virtually unknown for the MTB versions.

[HillDancer]

I've found heat to limit my road disc (steel) brake performance on paved, steep, technical descents, requiring frequent and/or continuous brake applications. With a front rotor size less than 200mm, and rear rotor less than 180mm, pads would glaze, resulting in fade & noise; not an issue with 200/180mm size rotors and SwissStop Green pads. Different pad compounds had varying deteriorating performance thresholds, but none that I used were completely effective on their own.

When I'm flat-land riding, I still enjoy the low lever effort and stellar modulation the large 200/180mm rotors provide, and I don't mind hauling the extra weight of them in the least. There is future promise of overcoming the weight and possibly size issue, but for now, massive heavy steel has advantages.