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RE: Belt Drives

Here's a claim from an outfit that does conversions.  I know, I know,
where's the DATA?

"Typical chain efficiency is approx. 80% when new, and deteriorates
throughout it's life. Typical belt efficiency is approx. 98% throughout
its entire lifespan. Due to change of pulley ratios, the engine RPMs are
reduced by 28% @ 60 mph. Feels like you have a 6th gear!"

Their website:

- -----Original Message-----
From: owner-oilheads@xxxxxxxxx [mailto:owner-oilheads@xxxxxxxxx] On
Behalf Of Tom Brown
Sent: Monday, September 12, 2005 8:14 AM
To: BMW Oilhead List
Subject: Belt Drives


>It may sound like blasphemy today, but belt drive may the the way of 
>>the future for both reliability and durability.

I've long felt that belt drives are the best solution to the problem of
getting power from the engine to the rear wheel.   I don't know what the
energy loss is with these things or if there are any other trade-offs,
but they seem like a lot better deal than chains for street use and a
lot less complex than shaft drive.

The new K bikes would benefit especially from belts as they're now
saddled with an extra set of bevel gears to turn the engine rotation 90
degrees which robs a significant amount of power.  Although the K has a
bit more power than the Hayabusa at the crank, it's got quite a bit less
at the rear wheel. Also, the real long wheelbase (longer than the old
KRS) is partially because of these driveshafts, which, by the way, I
don't think look that nice on the K, especially the semi-gloss black

However, can you beat the look of the new hex head rear drive units?
heavens, are they beautiful or what?

I'm reminded of the little green Simca 1000 two door coupe' I saw
while riding in the Wisconsin countryside.   It was perfectly restored
painted a beautiful British racing green with a tan and black interior.
It was one of those elegant Fiat 2-door coupe bodies, reminiscent of an
Alfa GTV,
but smaller and even cuter.   With a 1 liter engine.  You're obviously
the gears like a road racer just to keep up with traffic.  The car could
have weighed much over 1500 pounds.   I chose the cafe in this town for
breakfast only because the Simca was parked in front.   When I arrived
in the
restaurant, I picked out the couple that I decided must have arrived in
this car.  When they got up to leave, I got up and looked out the front
window...sure enough, it was them.    What a perfect car for a drive to
breakfast on a perfect Sunday morning in September.

A car like that must have cost the owner at least $10,000 in restoration
lots more in sweat equity.   What a deliciously impractical way to spend
and money!   I'm sure the car is not speedy or particulary strong in any
aspect.   Even handling is probably not much better than "interesting".
not what one thinks of as a collector car, like a Jag or Ferrari.  It
however, one of the most attractive cars I've seen in a long time.   No
and no driving it in the winter.  It's a Fiat, basically, and we know
what happens to Fiats that are put outside in the winter.

By the same token, we all know that there are faster and more reliable
bikes than a BMW, but BMWs have a certain combination of "somethings"
that keep our
interests.   It's engineering blended with styling.  The bikes and the
seem to be made beautifully inside and out.  I don't always agree with
the German preference for the occasional whimsically over-complicated
The new servo brakes are one recent example of that.   I've adapted to
but I think I like the plain, non-ABS really strong brakes on my Aprilia
better, plus, I like that I can change the fluid myself without the aid
of a dealer-only computer.

BMW has been known to make design decisions based on asthetics and on
expectations about what's expected of them as a German maker of fine
machinery.   For this reason, we may never see an R bike in our
lifetimes with
a belt drive....Too simple!  Not pretty enough!

Will we ever see a boxer 2 or 4  or even 6 cylinder water cooled boxer
BMWs Valvetronic valve system?   I happen to think that system would be
ultimate answer for a boxer bike.   No more throttles, no more heavy
valvetrains, cams and chains.   Seamless electronic control of valve
for fat torque curves without the need for really long stroke which adds
vibration.  This would surely result in further weight reduction and
more HP, not to mention better fuel economy and lower emissions.  I get
crazy just thinking about it.  BMW has all the technology to do this. In
fact, expanded use of the electronic valve assemblies used in the cars
would bring down the unit costs.  They just need to apply it.

I believe more of these belts will be seen replacing chains in the
BMW/Aprilia singles that are coming soon.  They are already being used
on the "Scarver" 650s, but not on the GS version because the belts used
on these bikes behave
badly when rocks get between the pulleys and the belt.   Technology
appears to
be marching on and the new belt designs are supposedly more rugged.
always felt this would be the right solution if the belt could be
without adding a lot of weight or hurting asthetics too much.   I've
H-D for going to this sytem.  A big plus with these is that there is no
periodic oiling required.   A huge plus for touring.

Anyone know if these new belts skim off more hp than BMWs' driveshafts?
does it compare with a chain in that respect?

- -TB