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Richard230
24 May 2011, 0852
Check this out. Very interesting. I think there are very few motorcycle racers using carbon fiber as a structural component in their frames. I looks like Brammo is pushing the technology and engineering envelope and not just in electric power:

http://www.reinforcedplastics.com/view/18120/brammo-empulse-motorbike-employs-carbon-prepreg-to-reduce-weight/

Allen_okc
24 May 2011, 0912
this is going to sound stupid, but could a motorcycle become too light?

electriKAT
24 May 2011, 0943
It appears they are referring to the race bike. I wonder what the chances are of CF making it into the production bike.

Hypotehtically, if they could build a 150mph bike that weighed 10 lbs, that would probably feel weird. But for all practical purposes, I don't think it's possible to build a motorcycle that would be too light.

Nuts & Volts
24 May 2011, 0944
this is going to sound stupid, but could a motorcycle become too light?

Maybe, but I would say that wouldnt happen until a motorcycle is less than 200 lbs and a ride is less than 100lbs. The lighter weight a motorcycle is that less power it needs and less energy it uses to accelerate. Now weight is good because you increase traction at the wheel. So if you remove enough weight you can lose traction with same torque. Meaning less torque can be effectively used to accelerate you forward and you hit a acceleration limit. You can increase the traction again by making your tires stickier.

Ex: A 400lb bike, with 150lb rider breaks traction at 200Nm to the rear wheel. Take out 100lbs and the motorcycle may break traction now at 170Nm. F=m*a, so
200=550*a, a=0.364
170=450*a, a=0.377
In this case less weight is better, but say you take out another 100lb and traction is now lost at 120m.
120=350*a, a=0.343
In this case you accelerate slower

All those numbers are made up, so in reality it all depends on how the removed weight affects traction. Also this argument is about accelerating from a standstill and the arguement changes when you accelerating at speed.

ZoomSmith
24 May 2011, 0958
Richard, I don't see where they said any frame components other than the seat assembly. Replacing the sub-frame and seat/tail pieces with a self-supporting CF tail-section is commonplace in racing. Still pretty cool though.

The title of that article is misleading. I wouldn't really consider the sub-frame to be a structural component.

Here's one you can buy for a Ducati.
Carbon Tail Section (http://www.weridemotorsports.com/Double_Dog_Moto_eXoskeleton_p/dd5r%20-%20cf.htm)

moparren
26 May 2011, 1153
The other thought behind obsessive lightening is that if you do have to add weight, you can put it where it does the most good.


Maybe, but I would say that wouldnt happen until a motorcycle is less than 200 lbs and a ride is less than 100lbs. The lighter weight a motorcycle is that less power it needs and less energy it uses to accelerate. Now weight is good because you increase traction at the wheel. So if you remove enough weight you can lose traction with same torque. Meaning less torque can be effectively used to accelerate you forward and you hit a acceleration limit. You can increase the traction again by making your tires stickier.

Ex: A 400lb bike, with 150lb rider breaks traction at 200Nm to the rear wheel. Take out 100lbs and the motorcycle may break traction now at 170Nm. F=m*a, so
200=550*a, a=0.364
170=450*a, a=0.377
In this case less weight is better, but say you take out another 100lb and traction is now lost at 120m.
120=350*a, a=0.343
In this case you accelerate slower

All those numbers are made up, so in reality it all depends on how the removed weight affects traction. Also this argument is about accelerating from a standstill and the arguement changes when you accelerating at speed.

Allen_okc
26 May 2011, 1257
my thoughts was on stability in normal daily traffic... compare a bicycle's weight in the wind compared to a motorcycle's weight in the wind... i know my 80cc gas powered bicycle at 40mph becomes very unstable in the wind compared to the honda 350 i had...

jazclrint
01 June 2011, 0539
Ducati's MotoGP racebikes uses both a carbon fiber frame and swing arm, but it's not without it's issues in terms of fine tuning the ride, from what little I've read and heard. CF is great, but you can't repair it (or can you?). I don't see it being a production bike material for that reason. Can you imagine the replacement costs? [shudder] I'm not sure what other manufacturers are using CF chassis parts in racing.

Allen_okc
01 June 2011, 0552
i would stick with a aluminum frame, it just seems to me that a carbon frame can crack after a period of time and like jazclrint said, shudder the expensive to repair or replace a carbon fiber frame.

fairing and fenders cool...