|v-brakes on a road bike?||phlegm|
Sep 10, 2002 7:41 PM
|Is there any reason why I can't put v-brakes on a road bike? I know they're more power than I need, but I have a spare set. Do I need any special hardware to do this?|
|re: v-brakes on a road bike?||Atombomber|
Sep 10, 2002 9:10 PM
|You need the proper mounts. Road brakes mount through a hole above the wheel. V-brakes require canti posts mounted to the fork or the seat stays.|
Sep 11, 2002 3:13 AM
|Even assuming that your frame had post mounts for cantis (which is all V-brakes really are), you wouldn't like the result. Mounts and hardware aside, physics is your enemy on this one.
Major reason people rarely use full-length V-brakes even on 'cross bikes, and the 'mini-V' or 'frogleg' canti has become quite popular instead for the heavier rider in search of more power: The contact patch of a road tire (even a 'cross tire) is simply too small for the amount of leverage generated by V-brakes. Couple that with adherence (your tires 'stick' to the road a lot more than an MTB tire 'sticks' to dirt) and you have a classic recipe for lockup, tire skid, endos, washout and all the other joys of overbraking. Added to which V-brakes don't modulate or work well with roadie levers (cable pull issues).
Sep 11, 2002 6:20 AM
|(Snip)>Added to which V-brakes don't modulate or work well with roadie levers (cable pull issues).<
V brakes work well on road TOURING bikes. I have them on my Miyata commuter/tourer. I have set of DiaCompe 287V levers, which are designed for V brakes. I find the stopping power to be better then the 3 different sets of canti's I tried. I also find the V's to much easier to set-up and get adjusted. Note that I'm using LX non-pivoting V's. The newer LX pivoting V's I have on my recumbent suck.
Sep 11, 2002 9:15 AM
|I've seen those. That's what sparked the idea.
If I used a cross/touring frame like the Soma Double Cross (http://www.somabikes.com/frames.html), I could mount v-brakes, right?
Sep 11, 2002 12:10 PM
|Can get a set of "Travel Agents" to resolve the cable pull issues. This would give you the ability to have STI/Ergo shifting with a V-brake bike and not be an endo-king. 'Cross guys do it all the time.|
Sep 11, 2002 4:17 AM
|I had a cross bike that came with some cheapo cantis. I was always fiddling with them and they never seemed to have enough stopping power. I bought a set of XT v-brakes. These require a device called a travel agent to work with STI levers. They did work much better than the cantis, but not nearly as well as regular road brakes.
A bike mechanic told me that to really get them to work as well as road brakes, you'd need a really large travel agent.
There is a reason road bikes come with road brakes. If v-brakes were better, people would be using them. Its not worth the trouble and expense (2 travel agents will run around $35). Buy a new tire instead.
Sep 11, 2002 5:27 AM
|As nearly as I can tell, all brakes do is slow you down.
Truthfully, unless you have some unusual use or special riding condition, you really don't use the brakes on a road bike very much. Besides, modern dual pivot brakes are so good that Campy sometimes uses a lighter, simpler, less powerful rear brake.
Now here's the other side of the story. Linear pull brakes with a Travel Agent are pretty much the industry standard for road tandems. Raoad tandems have twice the weight of a single bike so they work fine for that use.
The mechanic that said you need a really big travel agent is addressing a completely different problem that is actually related to WWI era aircraft. Way back in the era of straddle hanger canty brakes and pulleys on the stem, a rider broke his front brake cable. This caused his straddle cable to drop down onto his tire where it caught a knob and caused him to flip over the bars. His lawyer found an old engineering standard for control cables and pulley size that dated back to cable operated aircraft and consequently established negligence by the bike manufacturer. After that, Shimano changed its canty hardware to link wires that pull through if the brake cable breaks and don't catch tire knobs.
|So why didn't they work for me?||pmf1|
Sep 11, 2002 6:42 AM
|They're pretty easy to adjust. I did have to worry about the pad being too far from the rim because that led to lack of power. And since the pads wore out pretty fast (compared to conventional ones), I did find myself monkeying with them from time to time. They also do not modulate very well. Either on of off, not much in between.
So would you stick a pair on your road bike just because you have them laying around? I sure wouldn't.
Sep 11, 2002 6:05 AM
|Others put it well, too.
I've never found a situation in which I did not have enough braking power, and I regularly plunge down huge mountainsj with twisty roads. Ordinarly side pull calipers have more power than the tires have traction; more power still will simply skid tires.
Plus, you'd have to beef up the fork to resist the force. Road forks just aren't made that way.
Some tandems have them, due to twice the weight. They've been known to literally melt brake pads, though.
Bottom line -- don't even consider it.
|on a tangent||Jofa|
Sep 14, 2002 6:27 AM
|you won't ever skid your front tyre, in a straight line, on a dry road: well before that, you will go headlong over the handlebars, however low you try to get your body in preparation. This would be easy to do, however, with the ordinary brakes you refer to, which have been used for decades, so it is lucky that we have an instinctive self-preservation which prevents us from squeezing the lever that hard.|
|but -- I want evidence, not theory||DougSloan|
Sep 14, 2002 2:07 PM
|Many times braking occurs in less than ideal conditions (for braking), like in a turn, while maneuvering, after the back starts to lock and you are fish tailing, or with any debris or water on the road. Stronger brakes, with less ability to modulate, might worsen the situation.
I wonder whether what you say is true, that you'd endo before skidding the front. Anyone want to experiment? :-)
Sep 14, 2002 3:03 PM
|And its for those reasons you cited that I qualified my point by referring to a dry road and an upright bike. I mentioned it not out of bloody-mindedness, but because I think it's generally surprising - and consequently interesting - that this is the case: most people intuitively feel that they might skid the front wheel from braking alone, and furthermore feel that if they don't, they might be able to brake at the limit of their grip by hanging their arse off the back seat.
I've never tried it of course... at least not on purpose. But plenty of people sail over their handlebars, when their stuation seemed so apparently hopeless that they squeezed the brakes fully, and flipped the bike. Physics worked against them: pehaps we could lobby those accommodating gents at Jackass TV to do some experiments for us.
Sep 14, 2002 3:09 PM
|that's 'back seat'... as opposed to...|
|I've tried it||off roadie|
Sep 15, 2002 7:38 AM
|I used to do nose-wheelies on my commuting bike a fair bit, just to scare the crap outta jayalkers that stepped in front of me. This was with some pretty cheap brakes (dia comp centerpulls, nicely adjusted but cheap) and nice sticky touring (Conti pro 27x 1 1/8) tires. Oh, and steel rims!
When I do a real panic stop on a bike with good brakes, I'm usually on the nose for 5 or 10 feet, and have to back off the brake to avoid an endo. I have lost traction on the front wheel, but never on a clean road. I've seen that exclusively on dirt, which is simply because the surface's shear strength is weaker than your tire's traction.
On the other hand, if you aren't panic- stopping, getting your body back allows some massive braking. If I put my weight back, its very hard to sqeeze the lever hard enough to lift the back end, even going down fairly steep hills. I use my front brake a lot even when descending steep dirt routes.