patentcad

I have created a bike/tech weenie monster with this stupid thread.

mrbubbles

This is the one. By MIN.



Disc is the future. I had one for a bad weather/long-distance-big-mountain-ride bike and it rules.

Tektro has a road disc caliper that's 100 gms lighter than BB7s.

Seattle Forrest

It's called a panic stop, and it doesn't feel any different based on the type of brakes on your bike.

big john

true dat

Minion1

Sorry but Im highly amused by the idea that Zipp is going to offer you superlight weight 303 rims built up 32 spoke 3 cross around a disc hub. Who in their right mind would pay for that? If Zipp and others are already pushing the limits at 16 - 20 spoke configurations, how are they going to deal with the different requirements?

Minion1

Why do you have to worry about heat build up with carbon clinchers?

BS87

Didn't old/cheap ones used to have problems caused by the heat of braking? Something about resins in the cf?

Shimagnolo

I read an article some time back (perhaps by Zinn) that the temperatures reached by braking are in the same range where normal resins used with CF start softening. This is a huge problem with clinchers because it means the air pressure can start pushing the sidewalls outward. For this reason, more expensive high-temp resins must be used to prevent this.

Bob Dopolina 

Novatec has two models available already.

Bob Dopolina 

If you design a disc specific carbon rim it means there is no brake track and that frees up design considerably - especially if you are designing tubualrs.

For instance, you could go wider and taller on the tubular bed which would alter both the contact patch and the interface between the tire and the rim. I'm sure there is a lot of room here for aero improvements. I'd image that guys at companies like ZIPP would LOVE to have this design restriction removed and be allowed to rethink this entire elemnt of rim/wheel design.

The weight of added spoks need for disc application would, most likely, be offset by the material not needed for brake tracks. It would pretty much be a wash.

To those only thining about stopping power your view is too limited.

Big John nailed it when he talked about long mountain descents. Caliper brakes give you Popeye forearms half way down the mountian and it only gets worse with brake fade. Add rain and carbon rims to the mix and it's an issue worth addressing.

bikepro

If Brunyeel thinks disk brakes are necessary, I guess he should know better than anyone. However, I'm personally not sure what advantage they would provide. I see where they would be better for high speed braking on descents, since they won't heatup the rims. However, I assume that disk brakes would provide more braking power from the brakes. But unless you can control the extra braking power, there will be more wheel lockups and skidding. It already easy enough to do this with rim brakes. Having never used disk brakes on a bicycle, do they provide better brake modulation? If so, riders would have better control of their braking.

Bob Dopolina 

Read the thread.

Usually this is completely pointless on BF but for this thread you might actually learn something both for and against on the subject at hand (with a few idjits sprinkled in).

mrbubbles

Stupid questions should be forbidden from people who haven't used disc brakes with 23c tires on road bike.

Guitarrick

Fairweather only not-so-mechanically-inclined (or not-so-mechanically caring enough for a leisurely bike ride) riders could benefit from sticking with v-brakes. Check out Kool Stop salmons. They're the $hite.

Whatever-weather riding as a usual mode of transportation people ---> discs could be your ticket.

I don't see the pros running discs anytime soon. Why bother? I don't know the weight difference of the lightest v-brake vs the lightest disc brake... that may be why..

I'm still trying to get my discs dialed in. Does anyone have a future disc brake TdF mechanic they can spare for a day?

Minion1

Cheers, you raise good points. But I still have reservations about the idea, because to my mind cable disk brakes don't have the modulation or power of hydraulics, and tbh I wouldn't change from rim brakes to cable disks - it's just not worth the bother, I don't think you'll gain that much. You can still burn your arms out braking using cable disks, it seems the expectation gap with disks is running away with people already.

WRT rim design, there will likely be another design restriction that we just don't know about yet...once a rim/tyre combination goes past a certain point, there may be diminishing aero benefits, if you remove the brake track the wheel may need reinforcing elsewhere, and while it may free up rim designers, (who wouldn't like a challenge like that to work on?) your assumed benefits have to overcome the fact that, on the front wheel for instance you'd have to nearly double the spoke count and add a rotor. This may be different for companies like Mavic and Fulcrum, who may be able to add fewer spokes because of their spoke design, but still that's a long bow to draw.

There may be tremendous advances in cable disk brake design, that I just don't know about and that make all my points moot. Also, if you're making long descents in the wet on carbon rims with a carbon brake track you probably need your head read, there's no safety device like common sense. I have a light, old aluminium box section tubular with a ton of spokes I use for rides like that. Brakes great.

I'm going to stick to my guns for now, that until there is a solution that allows hydraulic brakes to be used on a road bike the jump isn't worth making. I'm 99 per cent sure that at some point I'll be proven wrong, but who can't say that.

EDIT I'm only commenting on road race bikes. Cross bikes, tourers, tandems they've been around for ages and are a done deal.

ilovecycling

I don't think this makes sense. You said it yourself when you said the contact patch is already very small with the skinny tires. Increasing stopping power would only cause the tires to lock up that much faster. How could this possibly be a good thing? The riders aren't going down because they can't stop fast enough. They are going down because they are locking up the tires while going around the turns.

Comparing a motorcycle with a larger tire contact patch and another 500 lbs of weight is not a fair comparison.

Psimet2001 

Keep in mind that cross bikes and road bikes are virtually the same. Cross bikes have been racing in road races for a long time. can't tell you how many times I've looked up in a pack to see cantilevers in front of me. In the pro ranks they often show up for the spring classics as a way to gain mud clearance.

As you say - cross bikes are a done deal - therefore there will be road race ready bikes peaking into low end amateur races sooner rather than later. Spring races roll around next season I know we will see a few cross bikes here locally....and I am sure there will be a disc. Officials will be all over it, but it WILL happen. think about it.

bikepro

You know what? That kind of reply is totally unwarranted. I'm smart enough to know when I don't know something and ask a legitimate question. I've never found it necessary to attack anyone for absolutely no reason -- and I won't start now.

Bob Dopolina 

Do you ever get tired being ahead of the curve?


Bloody exhausting, isn't it?

SpongeDad

For cross, I always figured the entry would be people setting up on the front wheel as a disk and leaving the back as a canti. That way people with current frames would only have to buy a new fork / new front wheel, and they'd get the benefit of greater braking where it matters and eliminate brake shudder. This may be a stupid question, but is the front wheel also 130 or 135mm? For some reason I thought it was narrower (and now I'm gonna have to go downstairs and measure it, damn.)

Werkin

Front axle is 100mm

pbd

It's a matter of time before disks are common on road bikes, there are too few real disadvantages for them to not become common. Maybe they won't become the majority, but they won't stay rare for long.

Sure, changes will be required in the design and engineering of both the wheels and the bike. But they provide too many positives with too much open design space for engineers and designers to work in for them to stay rare.

Sure, you need strong mounts, more spokes, etc...but you can make the rim whatever you want it to be with no brake track, your wet braking is better, you get no brake fade, and with more R&D you won't be giving up any weight at all by the time it's all said and done. Plus any weight you do add can be moved from rim to hub, or even rim to frame/fork.

It's only a matter of time. Those Volagi bikes look awesome, and I think we'll be seeing more like them in the near future.

LesterOfPuppets

You really need a number?

How about a pic?

patentcad

I pump up my own bicycle tires you know.

Rowan

This is true. The cable discs on my MTB were very easy to align and the only issue I've had is rub from a bent disc that I bent by dropping the wheel.

And therein is one issue not dealt with here... the discs are the most "fragile" part in the mix, and people's clumsiness or carelessness are likely to produce issues with rub. Touring cyclists who use bikes with discs have always expressed concern about how to protect the discs in transit.