suicyclists again
in [Cars]
|
Prev: Hoover Dam Bypass and Vegas notes
Next: Illegal mexican with "suspended drivers license" pleads "no contest"to murdering 4 year old white girl.
From: Matthew T. Russotto on 11 Jul 2008 15:34 In article <f5vdk.61941$pe5.3735(a)fe115.usenetserver.com>, Arif Khokar <akhokar1234(a)wvu.edu> wrote: > >As you apply the front brake, you increase force to the point that the >rear wheel starts coming off the ground. Ideally you would want to keep >the application force constant at that point, but in reality, it's hard >not to decrease the amount of force applied. That in itself would >increase braking distance to some extent. The ideal for a bicycle would be to hold the front brake at the point such that when the bicycle stops, you just reach the tipping point at which the bicycle flips over. All things being perfect, you'd actually stop with the bicycle balanced over the front wheel (but since that's an unstable equilibrium, it isn't going to happen) -- There's no such thing as a free lunch, but certain accounting practices can result in a fully-depreciated one.
From: Matthew T. Russotto on 11 Jul 2008 15:37 In article <80549bc1-b072-43a9-aa7b-70f9d1ebf506(a)56g2000hsm.googlegroups.com>, DanKMTB(a)gmail.com <DanKMTB(a)gmail.com> wrote: > >What's your guess on the stopping distance? It does have knobbies, by >the way. I still think the limiting factor will be not flipping as >opposoed to traction, so I don't think it'll make much of a >difference. I'll say 38'. -- There's no such thing as a free lunch, but certain accounting practices can result in a fully-depreciated one.
From: Matthew T. Russotto on 11 Jul 2008 15:58 In article <FKKdnWUbKYHBEerVnZ2dnUVZWhednZ2d(a)comcast.com>, Brent P <tetraethylleadREMOVETHIS(a)yahoo.com> wrote: > >If you were correct, that means the rear brake and rear wheel would be >entirely useless for slowing. They are not useless for slowing. They are useless for a maximum-effort stop. >If the brake were useless it would be deleted to save weight. I'm sure that in many racing categories if they weren't required by the rules they'd be deleted. >Once you've weight shifted everything >on to the front wheel you've past the point of maximum braking because >now the rear wheel is doing nothing. It doesn't matter that the rear wheel is doing nothing. The braking force on the front wheel has been increased by as much as braking force on the rear wheel has been decreased. >I don't think you're stopping as fast as you think you are. And I simply >cannot fathom under what math a one wheel stop is better than two wheel >stop. If it were true we could delete rear brakes on passenger cars and >bicycles. Passenger cars do not shift weight forward enough during maximum braking to unweight the rear wheels, so they still need rear brakes for a maximum effort stop. >jumping and other such things. However, I've never found an actual >trail that was designed to be used to get from A to B that I could not >take a road bike over. And that includes the rocky thing in Iowa that >was called a trail to get to the top of the bluff along the miss. river. You'd take a road bike over gravel? A touring bike, sure, but a road bike with 25x700c tires inflated to 100+psi? -- There's no such thing as a free lunch, but certain accounting practices can result in a fully-depreciated one.
From: DanKMTB on 11 Jul 2008 16:00 On Jul 11, 12:37 pm, Brent P <tetraethylleadREMOVET...(a)yahoo.com> wrote: > On 2008-07-11, DanK...(a)gmail.com <DanK...(a)gmail.com> wrote: > > >> > I am of the impression you've achieved maximum braking when you've > >> > fully unweighted the rear tire. I can comfortable stop on the front > >> > wheel alone, rear wheel hovering. > > >> You've achieved it and past it by. > > > How so? Please explain. > > If you were correct, that means the rear brake and rear wheel would be > entirely useless for slowing. If the brake were useless it > would be deleted to save weight. I don't agree. The rear brake is still useful for poor traction situations, severe downhills, etc. > Once you've weight shifted everything > on to the front wheel you've past the point of maximum braking because > now the rear wheel is doing nothing. But if your weight is as far back as possible and the rear lifts, it seems to me the front wheel has just picked up the braking force the rear wheel would have applied. For giggles, I'll try some stops without allowing the rear wheel to lift as well. It'll be interesting to see, but I don't think I'll stop faster that way since I'll be required to use less front brake in order to allow the rear wheel to stay on the ground so that it can brake also. Assuming I cannot balance on the front wheel to stop I'd agree, but I find in all-out stops my bike ends up on it's front wheel. > >> > Where did skidding come into play? I don't even intend to touch my > >> > rear brakes, much less skid. > >> Front brake only eh... your fastest possible stop is a face plant. > > Without question. And if we allow over-the-bar tumbles (which still > > won?t equal a face plant, at least with me riding), I guarantee I can > > out stop most cars, and stop well under 30'. Being an experienced > > rider, however, I am able to brake hard enough to lift the rear wheel > > for some time without going over the bars. I do it on a regular > > basis. Kinda fun, and it facilitates a very short stop (even without > > the face plant). > > I don't think you're stopping as fast as you think you are. It's possible. I look forward to finding out. > And I simply > cannot fathom under what math a one wheel stop is better than two wheel > stop. If it were true we could delete rear brakes on passenger cars and > bicycles. Not all riders have the balance to brake so hard with the front that the rear wheel lifts. Passenger cars skid the front wheels before the rear wheels lift, so there's no relevence at all. I assume you know this. > > So, considering I can brake hard enough with the front to unweight the > > rear without going over the bars, please explain where skidding comes > > into play or how I'd stop any faster using the rear brake. > > First I said skidding _AND_ lifting. Unless you're going to > shift your weight over the handlebars to intentionally lift the rear > wheel it's going to skid before it lifts unless you don't use the rear > brake. If you're not going to use the rear brake forget about minimum > stopping distance. > > >> I don't drive or ride SUVs. > > Ever hear of the right tool for the job? I do a lot of my riding off- > > road, on very technical trails. What type of bike would you suggest > > for that style of riding? > > 'techincal trails' is that to say trails that are purposely designed for > mountain bike entertainment riding? Yes. > I suppose you'll need one for > jumping and other such things. Even without the jumps you need one for some trails, and it makes many trails far more enjoyable. > However, I've never found an actual > trail that was designed to be used to get from A to B that I could not > take a road bike over. And that includes the rocky thing in Iowa that > was called a trail to get to the top of the bluff along the miss. river. Who said anything about point A to point B trails? Most of my favorite riding is done in loops throughout a section of woods. The point is fun, not getting to point B. Here are a few examples of some of my favorite trails: http://www.livefreeandride.com/vietnow.htm http://www.between2wheels.com/photos/nh_fort_rock/dsc00192.html http://www.between2wheels.com/photos/nh_fort_rock/dsc00225.html http://www.bikerag.com/images/PICTURES/nh-exeter/Dsc00775.jpg http://www.bikerag.com/images/PICTURES/nh-exeter/Dsc00785.jpg http://www.bikerag.com/images/PICTURES/nh-exeter/DSC00803.JPG http://www.americantrails.org/i/resourceimages/vietNEMBA.jpg http://www.livefreeandride.com/plank.htm http://www.livefreeandride.com/headbreaker.htm
From: N8N on 11 Jul 2008 16:28
On Jul 11, 3:58 pm, russo...(a)grace.speakeasy.net (Matthew T. Russotto) wrote: > You'd take a road bike over gravel? A touring bike, sure, but a > road bike with 25x700c tires inflated to 100+psi? I often ride on a gravel alley near my house because it saves me from having to cross a four lane road. granted it's only ab lock long but no worries. I think my tires are actually 32s but I've been thinking of trying narrower ones (my bike is a CX model because I wanted a road- feeling bike that could be abused and smacked around, and ridden on semi-rough trails without worry) nate |