chip.hedler

Interesting question: even if tire pressure is so low there is significant distortion of the tire from the weight on it, doesn't the same amount of tread have to be rolled onto the pavement for each revolution of the wheel? Or is it more like the fully inflated, unweighted circumference of the tire acts just a wee bit like the tread on a tracked vehicle when weight distorts the casing as you ride? Would there be a measurable difference marking the tire and the floor and moving forward EXACTLY one revolution if one trial was with a rider's weight and the other was with as little weight on the wheel as possible? Any theories?

beng1

I never have theories, only facts. Only the effective radius in a straight line between the axle and the road surface directly below it count in calculations.

beng1

Yes, a 25"er, and yours is in much better shape than mine, which has rust-spots and was once chain-sucked into destroying it's rear derailleur and hanger, it still has a few good hundred years to give though.

beng1

Pssssst, I also recently, and dozens of times in the past, said my Huffy was very fast, which makes your point moot. That is what happens when you cherry-pick....

clubman 

Those of us with very short inseams get more power in a forward position. I gravitate to short seat tubes and long stems. Seat angles also tend to tilt up with this positioning. This 110 pearl should be a 120.

chip.hedler

Well, have you gathered any facts about what happens with all that rubber that belongs to the full circumference of the unweighted tire? Are you stating as a data-verified fact that a wheel whose hub is, say 1/10th of an inch closer to the ground has an effective circumference that is 2/10ths times pi less than the circumference when totally undistorted, and therefore only rolls that far for one complete revolution? Maybe so, but then something must happen to that remaining rubber. What? Doesn't all of the tire have to make one full rotation each time the hub does? I don't have a theory about that, only some vague questions...Anybody else following this thread have some new ideas, or better yet, some actual facts to give calculations some meaning?

chip.hedler

What is what happens? A complaint about cherry-picking is so easy to lob! Good on you that your Huffy is fast, and that your SuperSport is also. In your view, are there any slow bikes, and if so, what defines them as such?

beng1

I can see if you have short legs and are trying to fit a larger bike the seat forward might help with the fit, I just do it to get my weight over the pedals as much as possible to partially replicate the position a rider has on a newer or more race-oriented bike.

If you are trying to get maximum power to the pedals on an old style bike that has a relaxed seat-post angle, then you are pushing down on the pedals at an angle, and so you are also pushing your body back and up at an angle with a tendency to push yourself right off the back of the seat. This will not be noticeable except when the rider is trying to put as much power down as possible, while just cruising and putting little effort into pedaling, the force put into moving the rider on the seat will be small also. If there were no limit to a rider's strength or endurance, the only thing stopping them from going faster would be their weight, because once you quickly push down on the pedals with a force greater than your body's weight, then you are going to push yourself up off the seat into a standing position.

So if a rider moves the center of their weight over the center of the pedal cranks then they will pushing their body more directly straight up and not wasting energy pushing themselves backward off the seat, they can make their seat level with the ground then too, and they will be able to put all the weight they have into pushing down on the pedals. With my LeTour I can go up a very steep hill and push myself up off the seat, but it does not look like it because I am not moving forward or backwards from the seat when I am off it, and there is no sense in being more than a fraction of an inch off the seat because that is more work wasted, once you are off the seat it is a waste to lift yourself any higher than a quarter-inch.

Another advantage of having the seat far forward is that the bars are very close to your body, so in a climbing situation or a sprint you can pull on the handlebars for power because your body is so close to them you have much greater force than a rider that is stretched out like a flying super-hero.

It is fun to experiment and invent things and try them out instead of just following the leader. By the way I had an old teacher for tool&die named Gianelli, he is 90-some years old now and lives down the street. Try slamming the seat on this blue bike all the way forward, you will have to raise the post a bit to compensate, then take it out and ride fast and see how it feels. I would lower the bars as far as they will go too.

Mr. 66

Your theory is just that

beng1

The only place that all riders of bicycles are anywhere close to being the same average size and of the same ability is in the fantasy world of professional cycling, which is something a small fraction of one-percent of of one-percent of the population gets to "be".

So for all practical purposes there are no fast or slow bicycles, and there are no fast or slow riders. If I say a bike or rider is fast or slow it has no practical meaning because it is only true from my point of view and has nothing to do with that of anyone else. If I can ride my ten-speed bike at 19 or 20mph for ten or twenty miles, or my single-speed at 17mph for the same distance, then I will say my bike and I are fast, but compared to the me of 25 years ago I and those bikes are slow. Nothing about pro cycle racing has meaning at all to bicycling except for use in marketing products for the sake of profiteering. My only concern in acquiring bicycles and related equipment for FUN is that it costs almost nothing, as there is zero reason for cycling to cost any more than that.

chip.hedler

Absent your current clarifications, how would anyone encountering your use of "fast" in your previous posts know that it "has nothing to do" with the way that most of the rest of us would understand and use it? If you aren't trying to invoke the shared understandings that allow us to fumble toward each other using common language, what's the point of posting in public forums?

beng1

Psssssst, teaching people what is subjective and objective will help them fumble on, maybe you should read what you write.

beng1

It is terribly, terribly, terribly easy to look up information on seat-tube angle that backs up moving the seat forward on old bikes. With the slack angle of the seat-tube on 70s road bikes, there can never be a drawback to moving the seat forward if you are looking for some extra power and speed.

chip.hedler

beng1

So what is your point? If pro cyclists did everything correctly, then there would never be any change in technology or in riding styles in their sport, which there always is. Your assumption is that what I see, experiment with or discover has been seen, experimented with or discovered already, or is or has been mainstream. If it were, then it would not be so controversial as to have you and your pals spend so much time on it and being bothered by it.

Senrab62 

Yikes. He's back for the New Year. I was hoping this thread would stay down.