CHAINLESS BIKES ARE HERE (again)( this time it might take)

[alancw3]

interesting article!

http://www.cnn.com/2008/TECH/11/19/chainless.bicycles.ap/index.html

for years (ever since they started using belts on motorcycles) i have thought that for certain bikes like city bikes and beach cruisers this would be great improvement over the chain for all the obvious reasons i.e. low maintenance, clean simple, etc. not a big fan of trek but hey give credit where credit is due. it will be interesting to see how successful they are.

http://www.trekbikes.com/us/en/bikes/urban/soho/soho/

http://www.trekbikes.com/us/en/bikes/urban/district/district/

i think it is interestng how they handle the problem of replacing the belt with a bolt on dropout.

[Michael Maddox]

This is the same drivetrain that Spot is using, it appears, or at least it's the same belt.

I will be interested in seeing how the market responds to it, given Trek's appeal and saturation.

That said, will the belt drive become solely linked to the cruiser market and never find its way to performance bikes because of this?

[zap]

CoMo is specing belt drive to replace the timing chain on their top tandems.

[dogdriver]

A bud of mine has the Spot SS. Perdy nice package for a turn key mtb SS for $1400.00 (1900 retail, minus the fall/ economy in the crapper sales). The drive train is SILENT, and has thus far been nothing but perfect. He beats on his stuff, so I'm assuming that the durability is also there...

Cheers, Chris

[Der_Kruscher]

How does belt drive respond to muddy conditions? I've seen it suggested that it would be less than ideal but I didn't get the impression that the author of this statement had any first hand experience.

[dancinkozmo]

im holding out for shaft drive !

[csm]

judging from some of the recent posts about Israel, Record 11 and the new Great Depression....
we've got the shaft already.

[alancw3]

im holding out for shaft drive !

like the 1898 pope shaft drive bike!

[Marcusaurelius]

Hmm, well the shaft drive is interesting but I'm just wondering how much something like that would cost and how reliable would it be? Also how much more does it weigh than a conventional drive train.

[Lifelover]

Hmm, well the shaft drive is interesting but I'm just wondering how much something like that would cost and how reliable would it be? Also how much more does it weigh than a conventional drive train.


Ask and Wiki will deliver.

http://en.wikipedia.org/wiki/Shaft-driven_bicycle

[RPS]

I like that the takeup is built into the dropout interface. I can’t quite see all the details, but it appears that once adjusted the wheel can be removed and reinstalled easily.

For many riders short of racers I think belt drives in combination with frame-mounted gear boxes could easily replace derailleur systems. For normal riding and training I'd give up up to a pound or two and 1 or 2 percent efficiency to have a bike that required almost no daily maintenance.

[rwsaunders]

They use belt drives on motorcycles and think of the belt system associated with your car's engine. Why not a bike?

[dancinkozmo]

like the 1898 pope shaft drive bike!

NICE !!!

[RPS]

They use belt drives on motorcycles and think of the belt system associated with your car's engine. Why not a bike?I suspect the main problem to overcome is the amount of torque that has to be transmitted without having to add too much weight. Even though bike riders produce very little power (compared to motorcycles), it's at a very slow speed compared to engines. Think about the size of a typical motorcycle's rear-wheel sprocket that would be impractical on a bike (the bigger the sprocket the less tension required on a belt). Also, on a motorcycle a little stretchiness in the belt could make the drivetrain run smoother by isolating vibration, but on a bike a thin lightweight belt may feel a little spongee to the rider. Just my guess as to why it's taken a long time to become viable.

[fierte_poser]

meh...the district is a nice looking bike but at $929 it seems like a 2x markup.

[alancw3]

I suspect the main problem to overcome is the amount of torque that has to be transmitted without having to add too much weight. Even though bike riders produce very little power (compared to motorcycles), it's at a very slow speed compared to engines. Think about the size of a typical motorcycle's rear-wheel sprocket that would be impractical on a bike (the bigger the sprocket the less tension required on a belt). Also, on a motorcycle a little stretchiness in the belt could make the drivetrain run smoother by isolating vibration, but on a bike a thin lightweight belt may feel a little spongee to the rider. Just my guess as to why it's taken a long time to become viable.

i think belt technology has come a long way in the past ten years or so with the serpentine belts on automobiles. remember when cars had like three belts and you use to have to put belt dressing on them to keep them from slipping! now just one that is good for at least 60,000 miles with no maintenance.

[RPS]

i think belt technology has come a long way in the past ten years ...snipped......Actually, belts have been replacing chains in industry for a lot longer than 10 years (I’ve posted about this before). I’ve specified and bought a lot of equipment that was designed using cog belts – either to keep components in time (similar to camshaft timing on an engine) or to transmit more torque. They can also be cheaper, quieter, and a lot cleaner than chains.

What I was referring to is that belt drives are often limited by torque and not horsepower (think of it in terms of how much force the belt can take before it stretches too much, breaks, or jumps the teeth). Even though as a cyclist I may only be able to put out +/- ½ horsepower for a short time, the amount of torque at the cranks may exceed that of a Honda Civic engine’s output. And that is far more than what is required to drive the camshaft of that Civic’s engine. What I'm trying to say is that just because it's used on an engine doesn't mean the demands on it are equal to that of a bicycle. ;)

BTW, as a side not, many new OHC engines are going back to chains in lieu of using belts for cam timing.

[fierte_poser]

What I was referring to is that belt drives are often limited by torque and not horsepower (think of it in terms of how much force the belt can take before it stretches too much, breaks, or jumps the teeth).

And yet 'big torque' motorcycles like Harley's use primarily belt drive and 'big horspower' bikes like Japanese liter bikes use primarily chain drive. Do you know why that is?

[RPS]

And yet 'big torque' motorcycles like Harley's use primarily belt drive and 'big horspower' bikes like Japanese liter bikes use primarily chain drive. Do you know why that is?Sorry – wrong context. That’s the problem with not writing the complete “novel”. My posts are too long as is. :D

Power = Torque X RPM / Constant

What I was referring to -- without becoming too wordy – is that because a bicycle rider produces his/her power a such a very low RPM (compared to motorcycle engines) the amount of torque may be higher (at engine, not at drive wheel).

Drive belts care more about the amount of tension they have to deal with than how fast it is spinning (although that is important to a lesser degree also). So a belt drive that is designed to operate at higher speeds (within reasonable limits) can transmit more power. It’s much the same with chains too. If you could spin a bike at 200 RPM, the chain could deliver more power than it could if spinning at 50 RPM just prior to failure.

To answer your question specifically, I’m sure either type of motorcycle could be made to work with either belt or chain; although generally chains can handle more torque for similar sizes. More specifically, remember that motorcycles go through a transmission with gear reduction prior to the final drive (whether belt or chain final drive). Therefore, that the “big torque” engine of a Harley may put out more torque at the engine’s crankshaft doesn’t mean that it is delivering more “torque” to the rear wheel. Given the same motorcycle speed and tire size, the one with the greatest “horsepower” and not torque is the one that can deliver the greatest torque through the belt. And in that sense, the superbikes put out more power than Harleys (I think).

[William]

is runescape gold (http://www.runescape-shop.com/runescape-gold/runescape-gold.php) site safe?


http://dogslol.files.wordpress.com/2007/09/yoda6.jpg