|   the spin on 29ers and thanks to GF | bvh3
Dec 30, 2003 11:56 PM | | I would like to start in on the "fast food/I want it now" aspects of society in reference to some of the disgruntled among us, but that has been done.
I want to talk about spin.
first, I looked at my college physics text and determined that if the average mass of a rider and bike is about 200 lbs, the kinetic energy of the wheels might make up 1% of the total kinetic energy.
The further you get from that generous rider and bike weight, the less the wheels make a difference in the kinetic energy.
IF that is the case, the only real differences are gearing (torque) and how the wheel rolls over bumps.
Of course, the more you spin the better and faster you ride other things being equal.
I spin in a lower gear on a 29er an go the same speed as on a 26in bike. That is the effect of different wheel sizes using the same gearing, but the difference I notice is that it rolls over bumps better.
That is my spin.
Second, I would like to thank Gary Fisher for putting these bikes on the market. I am riding a paragon and I know several people who have recently purchased sugar 292s. I know that all of us love these bikes. |
| re: the spin on 29ers and thanks to GF | n8ofire
Dec 31, 2003 7:10 AM | | Thanks for the post, but it seems there is a bit of confusion over the "spin" topic, or I am at least confused about what you wrote.
A person's pedal cadence on a bike has nothing to do with the size of their wheels, unless you ride ss. Otherwise, you just shift gears to accomodate your ideal cadence. Just because you ride a slightly lower gear on the 29er to go the same speed does not make things any easier. Gearing is a function of chainrings and rear cogs AND wheels size. YOUR GEAR is actually the same!
The difference IS in how easily you roll over bumps and maintain speed.
Glad you're enjoying your bike. You're NOT alone! |
| At a steady speed, rotating weight doesn't matter | fastskiguy2
Dec 31, 2003 4:34 PM | | Ok, we don't ride the same speed all of the time but remember Moser's hour record disk? That sucker was huge and it sure wasn't light. I think rotating weight might be just a teeny weeny bit overrated. We need some studies, not opinions of guys who just dropped major coin for trick wheels. My 29" wheels don't seem to accelerate any slower but I'm biased too (29" wheels RULE)!. I mean, 500g in a 220 pound rider/bike weight just can't make that much of a difference. |
| rotating weight == flywheel | team_bfd
Jan 1, 2004 9:03 AM | | In the wide world of engine-driven wheeled vehicles, there is
a thing called a flywheel. It's a balanced, weighted wheel
bound (clutchless) to the drive shaft of the engine. Different
motors have different properties. The properties of the motor
and the desired operating characteristics of the whole vehicle
dictate the weight of flywheel mated to the engine.
Some vehicles are meant to be light and accelerate quickly. They
have really light flywheels. Some need a balance of acceleration
and power (horsepower and torque). A little flywheel weight can
make the power feel more smooth and regulated, and can help them
coast along efficiently once they are up to speed. Some vehicles
need to come up with raw power to haul a load--acceleration isn't
so important as the ability to haul the load at a relatively
constant speed, even up hills and for a long time. Heavy flywheels
help them maintain rpm, and their engines are well-suited to
dealing with a significant but steady load. And they can't
accelerate worth a damn anyway.
Different riders have different reasons for being out there.
Some of them are competitors in relatively short races. In
cycling, track racers are the 2-stroke moto-cross bikes. They
travel light, carry no cargo, brake late into tight corners,
accelerate hard out of them. XC offroad racers have to have a
slice of track racer, a good dose of climbing torque and steady
endurance, decent control in fast descent, etc. Jack of all.
Sometimes you can put a 4-stroke moto into a race with 2-strokers
and it'll do OK, maybe even excel. Probably because the operator
knows ways of exploiting properties of the ride that make the marginally poorer windup speed less of an issue than one might
expect. Maybe he's able to rip through the berms faster because
of the higher total weight of his rig.
Others are longer-haul specialists. Endurance racers are the
diesel sedans--plenty of steady power, endurance, and efficiency,
but still fairly fast and flexible. Doesn't matter if they can come
out of the corners as fast as a 914. Fully loaded tourers are the
big rigs. Doesn't matter how fast they go, as long as they have
enough torque and enough gears to get over the mountain.
Different horses for different courses. I don't have much interest
in traditional XC anymore. I never was much good at being really
fast for 90 minutes, but I've always been OK at all-damned-day stuff.
Get those wheels rolling and keep 'em rolling. Diesel .vs 2-Stroke.
I had some nice light 26 wheels during my time on traditional mtbs.
Didn't make much difference to me. That doesn't mean 29ers rule and
26ers blow, any more than it means the opposite. Just means 29 works
well for me. Better than smaller wheels.
All this recent trolling saying 29 isn't going anywhere--hell I
think it's already somewhere. It isn't for everyone, just as SS,
fixie, fully rigid, long-travel downhill, or
isn't for everyone. Even if we never get 2.3 rubber, I'd much rather
run a 2.2 Jones up front and most any 2.1 rubber on the back of
a big wheel than 2.5s on 26" wheeled bike. My 2.2 Jones feels
bigger by far than the 2.3 Conti Vertical I was running on my
26" bike. For the kind of riding I do, and for the size of bike
I ride, it's just a better fit.
My engine never has run right with a light flywheel anyhow.
My $.02 on a clear but windy + chilly New Year's Day with a head
full of coffee and pastry. (isit warm enough to ride yet? isit isit?) |
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