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Disc Brakes on a road bike?(17 posts)

Disc Brakes on a road bike?CyberJay
Dec 21, 2002 8:20 PM
I've heard opinions both ways.. I'm curious for more ideas.

I'm 6'4" and 320lbs. 7yrs experience MTB, last two have been DH oriented. I work at a shop that is mostly high end road and I feel I need to get a road bike to take my involvment with the customers to the next level. I have all my choices made except brakes.

The ONLY reason I want discs is because I'm worried heat from my rim brakes would cause my tubes to pop on long downhills. It happened to me on my MTB when I was using Magura rim brakes, I'm worried it will happen on the road.

My boss and some other riders think discs are a good idea, just so I can have more power or whatever. Frankly I'm not too worried about power.

One of my riding buddies who is an accomplished road rider with MANY years of experience insists that CXP30s w/ regular road calipers will be enough for me.

I'd like to avoid discs. I've used MTBs with 1.25" slicks in the winter for years. I want my new bike to be a classic road bike. However, it will be useless if it can't withstand high speed braking. I like going downhill fast, I know this will be one of the driving forces behind my road biking. I simply won't ride if I have to stay on the flats all the time, or ride slowly down hills.

Thanks for you ideas.

-Jay
re: Disc Brakes on a road bike?Akirasho
Dec 22, 2002 2:36 AM
... there has been a bit of discussion on this issue on the forums for a couple of months (especially when we espy disc equipped CX frames) and a search might net you some of the older threads... but I predict that it's inevitable as makers search out new markets (whether we need them or not is not germane to marketing... indeed, marketing strives to "create" need (look at the craze for cellular phones... yet for the first 100 years since the phone was invented, we seemed to be able to wait until we got to work or home)).

Bicycles are certainly not immune to said (there are rumblings about "new" standards for headtubes on MTB's (1.5) as well as proprietary press fit BB's on road and MTB... a new "standard" for road bar diameters... integrated headsets... bazillion speed drivetrains, etc) and ultimately, beyond anyone's opinions, the market will show the way (ain't Capitalizm great??!!??).

My personal prediction is that we will see prototypes in the Euro Pro peloton in '03 (on select venues/stages/events). Again, because of developments in CX, the basics (frame and fork fittings (look at Cannondale's disc equipped CX)) are already in place (shave weight, line up proprietary disc rims and hubs from major wheelsmiths and wait for many of us to go gaaaah gaaaah).

We abide.

Remain In Light.

Be the bike.
re: Disc Brakes on a road bike?motta
Dec 22, 2002 5:19 AM
You must get disc brakes! I see riders bursting tires on almost every descent, and if they use sew-ups the glue becomes soft and tacky and the tire rolls. It is not a pretty site. One guy reached down to clean off his tire, his rim had built up so much heat he got third degree burns. Had to be airlifted to the local hospital.
As for me I am afraid to go that fast down hills, but my friends always wait for me at the bottom.
on 2nd thoughtmotta
Dec 22, 2002 6:21 AM
Consider the fact that discs will add alot of weight, at least 75 grams per wheel(rotating weight) and that there are no ski lifts in road cycling, so you will want to keep that in mind, especially when dragging your considerable @ss up the other side of that hill.
Good point but...CyberJay
Dec 22, 2002 6:39 AM
My "considerable @ss" has been riding bicycles up and down hills for years. And since my @ss is so considerable, 75g means almost nothing to me on the bike. Thanks for the input though.

-Jay
All brakes do is slow you down!Spoke Wrench
Dec 22, 2002 5:43 AM
I don't know where or how you ride, but honestly, most guys don't use their brakes very much on a road bike. For typical road use, overheating the rims would be a very unusual occurence.

Tandems are a possible exception. Tandem riders tend to continuously drag a brake on long downhills and seriously heat up their rims or Aria drum if they have one. If that's your concern, an ordinary closed system hydraulic disc brake isn't going to cut it. The issue is they heat up the hydraulic fluid too much and the brake locks up.

Santana had Formula design an open hydraulic system disc brake for their higher end tandems, but they are touchy to adjust and still have brake fluid boiling issues (I use DOT 5.1 hydraulic fluid for road raceing motorcycles in mine), and I don't think they stop as well as a mundane LX v-brake for routine use.
re: Disc Brakes on a road bike?bsdc
Dec 22, 2002 6:17 AM
Bottom Line: If you don't want disc brakes you don't have to have them. There are almost no road bikes with disc brakes and I have never heard of heat related blowouts.

I've considered disc brakes on my new road bike, but the bottom like is, I don't know of any disc compatible carbon fiber forks. I know you can get some steel ones. I don't think disc brakes are needed on road bikes. I just think it would be cool.
re: ... I wonder...Akirasho
Dec 22, 2002 1:22 PM
If you don't want disc brakes you don't have to have them.

... but, as with many high end MTB's coming down the pike, the frames are getting disc specific with nye a brake boss on the rear triangle... and fewer high end forks opting for both options... While it might not happen soon, it could go the way of a high end, high performance 1" threaded steerer MTB fork... with brake bosses.

Again, it's not about need. That's why I believe that the discs will be used on certain mountain descents, or inclimate venues where the cycling public can be shown why we need 'em. The salient points for discs on MTB's has already been made 'bout as fast as Sherman's march... and for the most part... accepted (I get the feeling that many frame builder's marketers are debating "when" not "if" every frame in their lineup will be integrated).

We abide.

Remain In Light.

Be the bike.
Not really necessary, butSnowBlind
Dec 22, 2002 9:37 AM
confidence going downhill is priceless.
I have yet to overheat my braeks, or blow out a tire on any decent (even Lake Tahoe), although you do outweigh me by ~50 pounds.

If you have'nt make a choice yet, I suggest you look at Campy brakes (even if you use them with Shimano levers).
Campy brakes are really good and the brakepad material is widely known for its long wear.
CXP 33 rims have a lot of material in them and will dissipate heat very quickly, but you will want to "pulse" (use the front, then the back in 3-5 second intervals) and feather the breaks to keep things cool. I tend to rely on the back brake to control speed and the front break to stop on long decents.
re: Disc Brakes on a road bike?merlint3
Dec 23, 2002 12:03 AM
Avid makes a decent mechanical disk brake, with a road specific ver that they claim will work with a road brake lever.

http://www.avidbike.com/2_cpsdiskbrakes/cps2_2_road.html

For a frame, an 02 model year Litespeed blue ridge or Appalacian model have the disk tabs in the rear (135mm rear spacing).

http://www.litespeed.com/english/2002_bikes/road/appalachian.html

(also I think Airborne's 03 Carpe Diem frame) I believe a CX fork can be found with the tabs for the front.

I plan on putting a disk on the rear and avid shorty cantilever for the front of a blue ridge. I am going to use a 36 hole Velocity Dyad rim w 28c wide tires. Although I weigh 100+ lbs less, I think disk brakes are the cats meow for mnt. bikes. So I will have extra insurance for loaded touring, especially downhill in the rain.

You might check though with Mavic on mating a Mavic 33 rim with disk brakes to see if there are any issues. I was cautioned some rims are not quite ready for disk brakes, although the Mavic is a very stout rim and should handle it fine.

I say go for it.
I'll make it easy for you: DON'Tfractured
Dec 23, 2002 12:40 AM
You don't need them. Period.

A good set of dual pivot brakes will always be able to lock up the tire, so there's no purpose for more power. You can definately get ceramic rims if you're concerned, but disk brakes for road bikes at this point are virtually unheard of, for a good reason.

As for heating up the rim, that shouldn't be a problem. The only time you would be braking that much is descending an entire mountain, switchbacks included. The point when road biking is to stay off the brakes as much as possible.

Don't expect road riding to be as exciting as downhilling... it's more of a passive enjoyment, like running.
custom road bike?kenyee
Dec 23, 2002 8:16 AM
I assume since you're working at a bike shop, you'll be getting a custom road bike? Or a standard cross bike?

As people have mentioned, most road bikes aren't built for installing disc brakes or the forks won't survive the stress of disc brakes. Cross bikes are built to take disc brakes.

There was a story on the Calfee forum about a crash a while back. One person had Campy Record, the other person had DA. The Campy Record rim brakes smoked slowing down for this sharp turn after a steep downhill and the person was able to slow down enough, but the DA brakes didn't (still smoked). The DA person ended up crashing into the Campy person's Dragonfly and snapped it in half (the guy ended up in the hospital for weeks). To me, that story sounded like a case where disc brakes would have been beneficial...

See if your shop owner would be willing to order two identical Serottas (or some other custom road bike maker). One w/ Campy Record and the other w/ Avid road discs and see if customers can notice the difference. If nothing else, it'd be a cool thing to do and would bring some extra business into the shop. :-)

p.s., road rims would be lighter if they were designed to not need the rim braking surface. The rotational mass out there would be significant compared to the 75g of the additional disc hardware at the axle. Of course, when we'd see such rims is anyone's guess...
Disc Rims will not be lighter.Paul Arlinghaus
Dec 23, 2002 9:43 AM
I thought that mtb disc rims would be lighter for the same reason (no braking surface). But look around at mtb disc brake specs, and you will find they are not lighter. The reason is that disc brakes put more stress on the rims. While disc brake manufactures love to say how close their disc brake system is to rim brakes, they forget to mention that the wheels have to be heavier to with stand the braking forces being transfered from the hub, thru the spokes, and to the rim. Also, the fork sees the braking force at the drop outs instead of at the fork crown. Thats a lot more leverage to over come. So a disc brake fork would have to be heavier to with stand disc brakes.
Aren't MTB rims thicker than road rims?kenyee
Dec 23, 2002 5:01 PM
I always thought MTB rims had to be sturdier because of all the rough terrain?
re: Disc Brakes on a road bike?Duane Gran
Dec 23, 2002 10:23 AM
I've read quite a few discussions on this. I'm no expert, but your description sounds like the first legitimate claim for a disc brake on a road bike. I'm a flyweight as they go and I still heat up my rims quite a bit on technical descents. I shudder to think of the heat build up you would face on a 15% gradient. As you pointed out yourself, 75g weight penalty is spit in the ocean. If someone makes a good disc for road bikes I wouldn't hesitate to use it.
Hell-forget the rims!!!Rusty McNasty
Dec 23, 2002 8:42 PM
I'd be worried that the tires would explode from the weight of your lard-@$$ sitting on them!!
320 lbs???? Holy $h!t!!
Have you considered an "adult tricycle"-you know-the ones with the big-@$$ wire basket on them?
Hey putz!Liberace
Dec 27, 2002 9:18 PM
He's probably one of the smoothest riders I have ever seen.
Maybe you should concentrate on bettering your overall self than putting others down.