Results and opinions on cx and road with discs

[Dave B]

Would like to hear feedback on those of you who have gone to disc brakes on your road and/or cross bikes.

What pros and cons have you noticed, not just in braking, but noise, feel, problems, etc.

Cheers

[Pete Mckeon]

Have not seen a need on road bike for I like the cantilever but disc sounds like an advantage in off paved roads. Challenge is how you put them on frame and currently made road wheels.


I am interested in also hearing from someone who made a conversion to disk - especially wheel and hub types and how connected to road farm.


Pete

[d_douglas]

This has been discussed extensively, but I will add my 2 cents:

I will likely NEVER own another bike without discs. I have commuted and CXd on a disc'd bike for 5 years now. I do not race, so bear that in mind, but for fun offroading on skinny tires, I highly recommend it.

Road wise, it is less useful, but I would still get disc only; in 2 years max there will be incredible road disc systems on the market.

Is it for a ti Desalvo?!?! :)

[Dave B]

This has been discussed extensively, but I will add my 2 cents:

I will likely NEVER own another bike without discs. I have commuted and CXd on a disc'd bike for 5 years now. I do not race, so bear that in mind, but for fun offloading on skinny tires, I highly recommend it.

Road wise, it is less useful, but I would still get disc only; in 2 years max there will be incredible road disc systems on the market.

Is it for a ti Desalvo?!?! :)

No not for a DeSalvo

I know it has been discussed at great lengths.

Just want to hear from people like you who did it. Thanks for the feedback.

What group are you using? Brakes as well?

Do you think 140 rotors on front and back be too little?

[rice rocket]

I have the Avid BB7s on 6500 levers, they're sorta mushy and lack the feedback and power of my XTR brakes. But then again, the XTRs are hydraulic...and they're XTRs. They are however, incredibly consistent.

I want to try Shimano's version soon.

[4Rings6Stars]

I have BB7 road discs and 140 rotors front and rear on my Soma Double Cross and love them. Stopping power is great. I've done light touring (loaded with about 50 lbs. of gear) and all weather commuting and never felt I needed more braking power. Only issue is they squeal some when wet. I'm using stock pads, FWIW.

I'm currently building up a DeSalvo cross bike and will be using BB7 discs on this one as well.

Necessary for the riding I do? No (but a 35lb 1960's Raleigh Sports would suffice for most of the riding we all do)
Worth the weight penalty? Possibly, because I hate cantis and haven't had good luck with mini-v's
Excellent stopping power, wet or dry? Yes
Easy to set up, maintain and adjust? Yes
Fun new technology? Yes

[ergott]

Next bike is in the planning stage while I wait for my turn to come up. I plan on doing a disc bike.

I'm leaning towards the new R45 disc brake hubs to be released. The bike will have 135mm spacing no matter what. I'd prefer to stick with a Campagnolo group so I have to choose hubs carefully. The R45 hubs are surely great hubs. I did hear from one big shop that wet weather performance isn't so great. I'm seeing if others find this to be true. White Industries disc hubs are 130mm for the road offering and that's a no go.

I'm also considering an Ultegra Di2 group, sticking with 10 speed and using Chris King ISO hubs. They are so "fire and forget" it's tough to pass over. Another option, Project123 hubs. They use I9 internals and are beautiful hubs to work with. Bottom line, 135mm spacing.

To anyone else thinking about wheels, think more about a disc 29er set of wheels rather than road wheels. The ideas and offering are better suited for what a disc brake road bike is usually intended for.

[maunahaole]

Eric - I'm doing a disc bike here soon. Are there any special considerations as to the wheel build when doing a disc brake wheel vs a rim brake wheel - i.e. does more strength have to be built in anywhere?

[ergott]

Crossed spokes all around.

Consider upping the spoke count by at least 4 if you are into low spoke count wheels. I would typically start at 24 spokes for real light riders and go from there. Me? I'm leaning towards a 32/32 build.

I like the idea of looking at 29er rims. Stan's notubes Crest or similar especially if you plan on tire sizes 28mm and up. Even better, Stan's make an Iron Cross rim that's 385g and no attention is payed to the traditional rim shape that used to have a brake track.

[FlashUNC]

Bike rumor has spilled quite a bit of ink about it. Including a lengthy article about some brake failure they dealt with.

[ergott]

On extended descents I've heard stories of all sorts of failures.

Disc brake failures
Clincher blowouts
Carbon rims warping
tubular glue melting causing the tire to come off

You name it. It's happened. The common theme, know how to safely negotiate tricky descents even if it means getting off the bike and letting the brakes cool.

[d_douglas]

The first time I descended a 'real' hill was a 17km descent in the Swiss Alps with Mr. Gothard. I borrowed his Sachs and after a few turns, he suggested that I lay off the brakes so much and start really diving into the corners. He said I was melting the tubular glue!

Anyways, scary as it was, the rest of the descent was a riot! Big descents require care with equipment on many accounts.

[bargainguy]

Funny, this just came out today on how Magura is not clear on how road bikes and discs play nicely together:

http://www.bicycleretailer.com/product-tech/2013/01/03/mag-road-disc-brake-safety-focus-new-magura-study

[oldpotatoe]

Next bike is in the planning stage while I wait for my turn to come up. I plan on doing a disc bike.

I'm leaning towards the new R45 disc brake hubs to be released. The bike will have 135mm spacing no matter what. I'd prefer to stick with a Campagnolo group so I have to choose hubs carefully. The R45 hubs are surely great hubs. I did hear from one big shop that wet weather performance isn't so great. I'm seeing if others find this to be true. White Industries disc hubs are 130mm for the road offering and that's a no go.

I'm also considering an Ultegra Di2 group, sticking with 10 speed and using Chris King ISO hubs. They are so "fire and forget" it's tough to pass over. Another option, Project123 hubs. They use I9 internals and are beautiful hubs to work with. Bottom line, 135mm spacing.

To anyone else thinking about wheels, think more about a disc 29er set of wheels rather than road wheels. The ideas and offering are better suited for what a disc brake road bike is usually intended for.

DT 350 disc...add a Campagnolo FH body and axle end and bob's yer uncle.

[oldpotatoe]

This has been discussed extensively, but I will add my 2 cents:

I will likely NEVER own another bike without discs. I have commuted and CXd on a disc'd bike for 5 years now. I do not race, so bear that in mind, but for fun offloading on skinny tires, I highly recommend it.

Road wise, it is less useful, but I would still get disc only; in 2 years max there will be incredible road disc systems on the market.

Is it for a ti Desalvo?!?! :)

I have discs on my Merckx and Moots...622mm rotor, rubber compound pads..works great.

[jr59]

I have discs on my Merckx and Moots...622mm rotor, rubber compound pads..works great.

Seeing as it was your birthday yesterday, I'll let this bad joke go! :butt:

[oldpotatoe]

Seeing as it was your birthday yesterday, I'll let this bad joke go! :butt:

tee hee

[VA-Scooter]

I have Avid BB7's & Di2 on a CX bike. Was not familiar with either when I ordered bike but love them both. They both do their job with very little effort,noise or adjustment.The only thing I do differently is I am real careful to be sure wheels are in the dropouts very square as I can not see the brake clearance. Spinning in stand sometimes it seems like they are dragging a bit. Not sure if they really are but I put bike on the ground & bump the wheels to make sure they sit straight. I use this bike for the road & a light duty Mt bike.

[10-4]

White Industries disc hubs are 130mm for the road offering and that's a no go.

White Industries MI6 hubs are 135mm spaced and can come in 24/28/32/26 hole counts with disc brakes.

[FlashUNC]

I have discs on my Merckx and Moots...622mm rotor, rubber compound pads..works great.

http://funnyasduck.net/wp-content/uploads/2012/11/funny-intense-pelican-woman-bird-see-what-you-did-pics.jpg

[10-4]

Bike rumor has spilled quite a bit of ink about it. Including a lengthy article about some brake failure they dealt with.

That "review" was a disaster. I would take that particular article with a grain of salt. Tyler (the editor) admitted later to using the wrong equipment (super-lightweight 140mm rotors if I remember correctly) for long descents and riding the brakes heavily on the way down.

Here's the article, read through the comments....

http://www.bikerumor.com/2012/02/14/road-bike-disc-brakes-are-coming-but-will-they-work/

[oldpotatoe]

White Industries MI6 hubs are 135mm spaced and can come in 24/28/32/26 hole counts with disc brakes.

stay away from the 26h. hard to find rims.

[10-4]

The common theme, know how to safely negotiate tricky descents even if it means getting off the bike and letting the brakes cool.

Bingo.

[10-4]

Funny, this just came out today on how Magura is not clear on how road bikes and discs play nicely together:

http://www.bicycleretailer.com/product-tech/2013/01/03/mag-road-disc-brake-safety-focus-new-magura-study

That's really interesting to read. I guess I wasn't SO wrong in ordering my new frame with rim brakes.....

[10-4]

stay away from the 26h. hard to find rims.

Zing.

[rice rocket]

The bike will have 135mm spacing no matter what.

Not 142? :)

[FlashUNC]

That "review" was a disaster. I would take that particular article with a grain of salt. Tyler (the editor) admitted later to using the wrong equipment (super-lightweight 140mm rotors if I remember correctly) for long descents and riding the brakes heavily on the way down.

Here's the article, read through the comments....

http://www.bikerumor.com/2012/02/14/road-bike-disc-brakes-are-coming-but-will-they-work/

True, but they also highlight some of the very real challenges brake manufacturers are facing in bringing this stuff to the road. Makes for interesting reading I think.

[cp43]

I've been running BB7's on my winter commuter / gravel road bike for 4ish years now. 160mm rotors, 36h x 3 cross all around, 135mm rear spacing. I'm 230 pounds, so I built heavy wheels.

The front brake squeaks a bit sometimes, even in the dry. Back brake, no problems. I'm running Tiagra STI levers, 8spd, lever feel is good for me, but I'm not picky about that.

When this bike gets replaced, it will be with something that has similar brakes. I'm not sure they're necessary, but I like them.

Chris

[BumbleBeeDave]

. . . might end up being a great idea, they're not something I will be an early adopter of. There will be brake and wheel failures under conditions of hard use and I don't want to be one of them. I've already broken my neck once and was VERY lucky. I don't want to do it again.

BBD

[David Kirk]

I've got two bikes that I have run discs on -

Cross bike - this bike is set up to only run discs and for cross they work near perfectly. It would be OK by me if they weighed a few grams less but it's not a big deal. I can see no reason to not use discs on a cross bike - they work better than a rim brake in the cold, wet or mud and they have loads of 'mud room' - and they have better modulation and power. I've heard some say that having more braking power is a waste as the tires are narrow and have limited grip anyway. While I understand the logic I have to call BS on this. The real advantage to a disc isn't that it's easier to lock the wheel and skid but that it's easier to bring the tire to the limit of traction (however much there is or isn't) predictably regardless of course conditions. In other words the rider can feel better what is going on with the limited traction the tires have and exploit it to the full. Discs will allow the rider to go deeper into corners with better control. I can't see how having two variable elements (brake friction and tire grip) is better than having one variable (tire grip).


I also hear some folks saying that disc ruin the sport because part of the charm of cross is that the stuff just doesn't work all that well and that this struggle with the gear is part of the appeal. Again - I understand the logic but I just can't see how having gear that doesn't work as well as it could is better. At the same time I don't see many of those folks that say discs are ruining the sport using bar end friction shifters very often just to be more 'core'. Brifters work better so we use them.

I think anyone that rides cross that tries discs will want to keep them........the beauty is that if they don't prefer them they can use rim brakes and life is good. Choice is good.





Road bike - I have a road bike that is set up to work with either discs or rim brakes and I've swapped back and forth a number of times to be able to compare the overall riding experience.

I live and ride in the mountains of Montana and that means two things......long hills and dry weather. I don't think I rode in the rain once this past summer but I rode nearly everyday.

The conclusion I've come to is that discs on the road may be just perfect for one rider and not so perfect for another - it all depends on where and how the bike is used. If the bike is ridden in the rain regularly then I think discs could be a good option. If the bike is used in the mountains in all weather conditions even more so.

If on the other hand the bike is used on flat roads, in the dry, then the advantages of discs will not be realized and the weight penalty would be for nothing.

For my personal use I waiver back and forth as to what I think would be better for a given day's ride. I really like the discs when the road gets really steep and curvy as they are so consistent and predictable as opposed to pads on a carbon rim that change feel and modulation dramatically with temperature. But - not every ride is in this terrain so there are plenty of rides that I hardly even use the brakes aside from having them prevent me from running into my own garage door when I get home.


I know there are some very strong opinions about road discs and that some think them an abomination..........and on the other hand there are folks that ride everyday in the wet who are thrilled to not have to replace pads and even rims all the time. I think that road discs are great for some and not so for others. If we all rode the same way we'd all ride the same stuff..........but we don't so the gear varies. Variety and choice are good.

--------------------

As a slight aside - I've been running the BB-7s on both these bikes. I too was concerned that I might overheat the brakes on long fast descents so I tried on numerous occasions to cook the things. I weigh about 185 pounds and took the bike down 10+ mile twisty descents and used the rear brake very poorly on purpose and dragged it much of the way. I was pedaling downhill with the brake on for a very long time and while I could get it pretty darn hot I couldn't get it to fade let alone melt. I'm sure others could get this to happen the same way one can melt tubular glue with rim brakes but I couldn't do it. Just my experience.

Dave

[Rueda Tropical]

Don't you need a beefier fork for discs? Not an issue for MTB suspension forks but wouldn't that make for a harsh front end on a skinny tire road bike?

According to the Magura article current road discs are often seriously undersized. The increased speeds and heat require much bigger beefier discs then mountain bike applications.

Is there that much of an advantage over modern rim brakes to offset all that?

[jr59]

I run discs on my Co-motion city view! It's set up more as a fast city bike than any thing else. They work really well and I like them alot.

No hills here, but a bunch of drivers that don't always stop when they should.
These things stop. All the time. Wet, no problem, dirty no problem. They just work.

The next bike I get will be more a road bike than the Co-Motion, but it will have disc brakes!

[David Kirk]

Don't you need a beefier fork for discs? Not an issue for MTB suspension forks but wouldn't that make for a harsh front end on a skinny tire road bike?

According to the Magura article current road discs are often seriously undersized. The increased speeds and heat require much bigger beefier discs then mountain bike applications.

Is there that much of an advantage over modern rim brakes to offset all that?



It seems to be a popular idea that the fork needs to be beefed up to deal with disc brake loads - this is understandable. But the question is 'beefed up compared to what?'

I think most carbon forks would not take kindly to having all the brake load on the bottom of one leg. The legs are just not designed to deal with that and with good reason. So in the case of a carbon fork I think most would need to be 'beefed up' in some way to be able to perform as desired and be safe.

IME - with steel forks - it's a bit easier to deal with. Most steel forks are beefier than many carbon forks and the material isn't directionally sensitive. In other words the nature of the material lends itself more to complex loads without a design change. So, in my case, after building way too many forks to test and ride, I've settled on using a heat treated blade that is slightly larger in diameter than I would otherwise use for a rim brake. It is very slightly stiffer than the rim brake fork but mostly it's tougher. I doubt anyone that rode one would consider the disc fork to be in any way harsh. I'm sure that carbon fork makers can also optimize the design to allow for the fork to be tough enough to work well and be safe. So while changes will often need to be made one need to know how big a change it is and from what baseline it was changed. I think the danger here would be saying that 'disc forks are stiffer and harsher' - I just don't think that needs to be true.

Rotor size - I've seen all different sized rotors being used. I've used 160F and 140R and it has worked very well for the way I've used them. Obviously one can go too small and heat dissipation is an issue but I think this will depend as much on the pads and caliper design as much as anything else. Suffice it to say that one can go too small and have heat issues - the debate will continue to be on how small is too small?

Are they worth it? Well..........I don't think anyone can say for sure and only the rider himself can say for sure. As with anything there is a compromise to be made with upsides and downsides to a given design. if you ride and commute in Seattle I'll bet they are more than worth it..............if you ride in fair weather in Miami then I doubt they will be. It all depends. No one size fits all no matter how much the market wants it to.

I hope that helps.

dave

[rice rocket]

IME - with steel forks - it's a bit easier to deal with. Most steel forks are beefier than many carbon forks and the material isn't directionally sensitive. In other words the nature of the material lends itself more to complex loads without a design change.
dave

Playing devil's advocate here, wouldn't carbon be better suited in this use case then? Disc brakes increase the directionality of the forces on the fork, meaning you can put the fibers exactly where you want it, and how you want it.

[David Kirk]

Playing devil's advocate here, wouldn't carbon be better suited in this use case then? Disc brakes increase the directionality of the forces on the fork, meaning you can put the fibers exactly where you want it, and how you want it.

Could be -

I think either material can be optimized to work well. It just takes time, thought and testing.

Steel is different than carbon in that one can't just add a layer where you want but instead the designer needs to decide what is best and seek it out or have it made. So steel blades can be made to work very well............and ..........they can be made to work very poorly. Just like carbon.

Dave

[Rueda Tropical]

if you ride and commute in Seattle I'll bet they are more than worth it..............if you ride in fair weather in Miami then I doubt they will be. It all depends.

dave

Thanks Dave. That was very informative.

Flat smooth roads and always sunny -gears, fenders and discs are all overkill for the riding I do here :)

[1/2 Wheeler]

Disc brakes are not the future. They are the present and to think otherwise is living in the past.

I'm a flat lander and while none of my current bikes have Disc brakes I will not get another one without them. I have riden them and they are better.

Superior braking is never a disadvantage.

[binouye]

White Industries MI6 hubs are 135mm spaced and can come in 24/28/32/36 hole counts with disc brakes.

WI also make those hubs with 145 rear, which is what we run on our tandem (with 200mm rotors and BB7 road, works well).

I also have BB7s on my dropbar 29er (Campy Centaur + jtek), 160 mm rotors, and I like them. Occasional squealing issues, but not too bad.

[rwsaunders]

When I purchased a city bike for my kid to use on campus, I went disc, as I knew that she'd be riding in wet weather, and that her maintence skills are non-exisitant. No hills to speak of on her campus, but regardless, not too many of us bomb downhill at 50 mph for extended periods. If she manages to not have it stolen, I'll consider it a success. It's definately being ridden and she has commented on how quickly the bike stops...ignorance is bliss.

I've considered converting my Poprad, as the frame was built for canti's and discs...I'd need a disc ready fork...but the I haven't been able to make it pencil. If I saw a 59cm disc Poprad come up for sale, I'd most likely take the plunge.

[ergott]

DT 350 disc...add a Campagnolo FH body and axle end and bob's yer uncle.

I did forget about using a DT mtb disc hub with a Campagnolo driver. Thanks for the reminder.

[dd74]

So can my Serotta Coeur d' Acier be retrofitted for disc brakes, that is if I wanted to go that route? I like the idea only because I wouldn't have to change pads when going from aluminum to carbon wheels.

Can any frame be retrofitted for disc brakes?

[RudAwkning]

stay away from the 26h. hard to find rims.

But not impossible! I've got a couple Mavic Helium front rims stashed away :)

[staggerwing]

So can my Serotta Coeur d' Acier be retrofitted for disc brakes, that is if I wanted to go that route? I like the idea only because I wouldn't have to change pads when going from aluminum to carbon wheels.

Can any frame be retrofitted for disc brakes?

Dunno about the backend, without extensive and expensive surgery. However, it might be perfectly reasonable to switch to a disc compatible fork (DK, will you make one a la carte?), and run a cable powered BB7 up front, with the rest of your setup remaining "as is."

Even though the rear carries most of the load when just pedaling along at a constant speed, weight transfer due to deacceleration dictates that the majority of your braking power is at the frontend.

[dd74]

Dunno about the backend, without extensive and expensive surgery. However, it might be perfectly reasonable to switch to a disc compatible fork (DK, will you make one a la carte?), and run a cable powered BB7 up front, with the rest of your setup remaining "as is."

Even though the rear carries most of the load when just pedaling along at a constant speed, weight transfer due to deacceleration dictates that the majority of your braking power is at the frontend.
Right, but I'd be afraid of flipping over as I've always heard discs are much stronger than calipers, this being exasperated even further when a disc is on the front and a caliper is used in the rear. What do you think?

[4Rings6Stars]

Dunno about the backend, without extensive and expensive surgery. However, it might be perfectly reasonable to switch to a disc compatible fork (DK, will you make one a la carte?), and run a cable powered BB7 up front, with the rest of your setup remaining "as is."

Even though the rear carries most of the load when just pedaling along at a constant speed, weight transfer due to deacceleration dictates that the majority of your braking power is at the frontend.

I asked a bunch of builders (including DK) about addign a disc brake tab to the rear of a steel cross frame originally built with canti bosses and every one said they wouldn't do it... That certainly doesn't mean it's not possible, just that it might be tricky to find a builder to do it.

[staggerwing]

Right, but I'd be afraid of flipping over as I've always heard discs are much stronger than calipers, this being exasperated even further when a disc is on the front and a caliper is used in the rear. What do you think?

Not going to happen. On the other hand, it will be easier to lock the front end up, but will have a more consistent feel, and be easier to modulate, in variable weather conditions. FWIW, the front is actually the end you would prefer to lock up, if it could not otherwise be avoided.

I'm quite looking forward to completing my disc braked equipped, Surly Karate Monkey, winter bike build and out in the icky stuff. Grabbed a big handful of brake the other evening on my normal commuter, a cantilever brake equipped Crosshairs, and my heart stopped while the greasy ice water burned from the rim and the pads began to take hold.

[mtb_frk]

I have been looking at the new redline conquest disc for my winter/gravel racer. I have Paul cantis on my current bike, they work but disc brakes would be nice when it gets snowy and icy. I never even think about my brakes on my mountain bikes which are all disc, I can't say the same for my cross bikes.

[NHAero]

I have discs on my Big Dummy commuter/errand bike and love them. Even if it's not raining the roads can be wet and have puddles and the discs just work. Almost all of my road bike rides are in dry weather, but I had a frame made this year and to allow the flexibility of touring, D2R2 type riding, and commuting I had it made to accept discs and haven't regretted it, though I haven't exploited their advantages in the riding I've done thus far. Many folks on this forum have multiple road bikes and get custom frames built regularly. Since this was the one frame for the foreseeable future I opted for the discs, knowing it would be heavier overall. They are BB7s and work well.

[thirdgenbird]

Dunno about the backend, without extensive and expensive surgery. However, it might be perfectly reasonable to switch to a disc compatible fork (DK, will you make one a la carte?), and run a cable powered BB7 up front, with the rest of your setup remaining "as is."

Even though the rear carries most of the load when just pedaling along at a constant speed, weight transfer due to deacceleration dictates that the majority of your braking power is at the frontend.

I'm glad I'm not the only one to think about this. It may not be elegant but it may be a great functional compromise.

-cheaper upgrade
-less weight than full disc
-braking where you need it
-no need to cram more stuff between the rear dropouts
-heat from front braking won't effect tire (rear is less of an issue)
-rear caliper safety net for those concerned about melting discs

[tuscanyswe]

I run discs on my Co-motion city view! It's set up more as a fast city bike than any thing else. They work really well and I like them alot.

No hills here, but a bunch of drivers that don't always stop when they should.
These things stop. All the time. Wet, no problem, dirty no problem. They just work.

The next bike I get will be more a road bike than the Co-Motion, but it will have disc brakes!

Thats a very practical good looking bike you got there!

Personally i will never put discs on a roadbike unless the market forces me to do so (more or less).

[mtb_frk]

For everyone running the BB7s are you using the road or mtb version?

[MIN]

I really want a Colnago World Cup Disc - looks fast and cheap enough to not worry about locking it up in the city or abusing it. Brake shudder is a concern for me with disc brake road/cross bikes though.

What are thoughts on the Foundry bikes with the thru-axel front?

[VA-Scooter]

For everyone running the BB7s are you using the road or mtb version?

Lynskey Cooper CX--Avid BB7-Road. Love them - They just do the job. Smooth quiet powerful. With Ultegra Di2 levers

[4Rings6Stars]

For everyone running the BB7s are you using the road or mtb version?

With road levers/STIs/Ergos? Road.

I have only heard of people using the mountain version on drop bar bikes if they were using linear pull brake levers.

[ergott]

I asked a bunch of builders (including DK) about addign a disc brake tab to the rear of a steel cross frame originally built with canti bosses and every one said they wouldn't do it... That certainly doesn't mean it's not possible, just that it might be tricky to find a builder to do it.

Maybe those builders (including DK) are trying to tell you it's a bad idea. I have no doubt you could find a sucker out there to do the job, but when well respected builders say no it's time to give up the ghost.

[4Rings6Stars]

Maybe those builders (including DK) are trying to tell you it's a bad idea. I have no doubt you could find a sucker out there to do the job, but when well respected builders say no it's time to give up the ghost.

Which is why I bought a disc specific DeSalvo and decided to try TRP 8.4 calipers on the IF instead...

[oldpotatoe]

some snipped

As a slight aside - I've been running the BB-7s on both these bikes. I too was concerned that I might overheat the brakes on long fast descents so I tried on numerous occasions to cook the things. I weigh about 185 pounds and took the bike down 10+ mile twisty descents and used the rear brake very poorly on purpose and dragged it much of the way. I was pedaling downhill with the brake on for a very long time and while I could get it pretty darn hot I couldn't get it to fade let alone melt. I'm sure others could get this to happen the same way one can melt tubular glue with rim brakes but I couldn't do it. Just my experience.

Dave

Discs on bicycles have been around for a long time. They are not really 'new'.

What has not been mentioned and a problem that has not been solved is overheating of a hydraulic disc brake on a road bike. THAT is what sram is trying to figure out(intro of their road wet discs delayed from Interbike, not sure where they are on it) and shimano says they will have in 2014(intro late 2013). Wet discs on a road bike is much different problem than cross or MTB. Lots more heat, much more braking requirements, ala, long, steep, twisty descents.

Smaller(gotta be light) calipers, reservoirs in the lever(less cooling), less fluid.

shimano has mentioned how they will re-engineer the hydraulic fluid to make the boiling point higher but in the cold, the fluid becomes like thick honey.

All the hub-bub about discs are like tubeless road. Avid BB7s have been around for how long? Transitioning to a 'road' bike is more popular now because of the commuting by bike/crappy weather/dirt road type riding increases seen in the industry.

Unless the above is solved(wet brakes and heat), I don't think you will commonly see a high-ish end road bike with mechanical discs anytime soon.

No Tarmac or Madones or the like with BB7s..

[David Kirk]

Hey Spud-mon,

I agree with all this and didn't say anything to the contrary.

dave



Discs on bicycles have been around for a long time. They are not really 'new'.

What has not been mentioned and a problem that has not been solved is overheating of a hydraulic disc brake on a road bike. THAT is what sram is trying to figure out(intro of their road wet discs delayed from Interbike, not sure where they are on it) and shimano says they will have in 2014(intro late 2013). Wet discs on a road bike is much different problem than cross or MTB. Lots more heat, much more braking requirements, ala, long, steep, twisty descents.

Smaller(gotta be light) calipers, reservoirs in the lever(less cooling), less fluid.

shimano has mentioned how they will re-engineer the hydraulic fluid to make the boiling point higher but in the cold, the fluid becomes like thick honey.

All the hub-bub about discs are like tubeless road. Avid BB7s have been around for how long? Transitioning to a 'road' bike is more popular now because of the commuting by bike/crappy weather/dirt road type riding increases seen in the industry.

Unless the above is solved(wet brakes and heat), I don't think you will commonly see a high-ish end road bike with mechanical discs anytime soon.

No Tarmac or Madones or the like with BB7s..

[oldpotatoe]

Hey Spud-mon,

I agree with all this and didn't say anything to the contrary.

dave

I know you didn't, just 'discussing'. You mentioned heat buildup in discs and I mentioned wet brakes and heat is a bigger problem, not yet solved.

[dd74]

My main issues about braking prowess stems from others on the road, namely soccer moms in Suburbans and their male equivalents in 3-series BMW convertibles who always seem to simultaneously be on the cell phone while not checking their rear view mirrors before a lane change, or figuring they can turn left in front of me with only 20 feet to spare. I can't tell you the efforts i've put both Campy and Shimano calipers through in these instances, all to the point I thought I'd snap the pads straight from the holders.

That's why I'm looking at disc brakes on whatever build I next take on.

As Mario Andretti once claimed that brakes win races, in my case discs might help me from being hopelessly bent.

[etu]

another advantage, if your frame has adequate clearances, you easily convert to 650b. i've been curious about this for a while. Recently built up a set and put on 650bx38 tires. Wow, it's a really neat ride - quick and plush.

[sworcester]

Every bike I ever had up to this point had non-disc brakes. I bought a Cannondale CadX aluminum cross bike with Shimano Ultegra when it came out a couple months ago. It uses Shimano levers with manual Cannondale disc brakes. Works well, not as throw-you-over-the-bars well I thought it would. Raced it and liked the performance. Interestingly in the snow (we don't get much of that stuff in North Texas) is the only time it squealed.
It has 160mm front and 140mm back rotors.

I thought I would vault over the bars when I slammed the front brakes. Maybe upgrade to BB7 or Ultegra just to see if they work better for the CX season in 2013.

Modulation is more than acceptable, may need some different pads or better adjustment. My thought process was mud, sleet, snow, dry, I wanted the same braking performance. The only race I did was mostly dry, one muddy creek crossing, and 35º weather, but they worked well.
Personally, I think they are the future, it just may not arrive in the same state it is today (think evolution).

[gavingould]

don't know if anyone cares, but top four finishers (might have been more than that actually) at the UCI cross race out in Chicago today were all on disc...

[oldpotatoe]

I'm glad I'm not the only one to think about this. It may not be elegant but it may be a great functional compromise.

-cheaper upgrade
-less weight than full disc
-braking where you need it
-no need to cram more stuff between the rear dropouts
-heat from front braking won't effect tire (rear is less of an issue)
-rear caliper safety net for those concerned about melting discs

Just make sure the fork is the same dimension, axle to fork crown, as the one being replaced. A lot of front disc forks are taller than standard road forks-since they go on cross bikes.

[thirdgenbird]

This is a very good point. In the unlikely event that I would do this, my first call would be to wound up. I belive they will let you add disc mounts to any of their forks and I think you can also custom spec crown height. I'm not sure how much it would cost, but it is still an option if you are attached to your frame.

[PaMtbRider]

I bought a Cannondale CadX....It uses Shimano levers with manual Cannondale disc brakes....

I thought I would vault over the bars when I slammed the front brakes. Maybe upgrade to BB7 or Ultegra just to see if they work better for the CX season in 2013.



A close friend bought one of these last week and I got a chance to ride it. Biggest disappointment was the disc brakes. No where near as good as BB7 brakes I have used. If the Cannondale discs don't improve dramatically after a few rides he is going to swap them out for the Avids.

[mccx]

I asked a bunch of builders (including DK) about addign a disc brake tab to the rear of a steel cross frame originally built with canti bosses and every one said they wouldn't do it... That certainly doesn't mean it's not possible, just that it might be tricky to find a builder to do it.

I've had the opposite experience. When I was looking around for someone to do this I was 3 for 4 finding builders say they'd be happy to retrofit a steel frame for rear discs. One of those was a well known builder who I'd consider unimpeachable in his framebuilding knowledge. The one who said 'no' said it was because his schedule was full and he'd rather do full frame builds that do retrofits and repairs.

[4Rings6Stars]

another advantage, if your frame has adequate clearances, you easily convert to 650b. i've been curious about this for a while. Recently built up a set and put on 650bx38 tires. Wow, it's a really neat ride - quick and plush.

I've thought of trying 650b on my new cross bike. I think I would be able to fit 2" wide tires...would be fun for the root/rocky New England single track I ride and probably d2r2 type rides as well.

Anybody have a set of Campy 650b disc wheels they want to sell??

[sworcester]

A close friend bought one of these last week and I got a chance to ride it. Biggest disappointment was the disc brakes. No where near as good as BB7 brakes I have used. If the Cannondale discs don't improve dramatically after a few rides he is going to swap them out for the Avids.

Probably what I will do as well. I wanted to see the Shimano's first though.