Belt Drives

["Tom Brown" <tbrown@xxxxxxxxxxx>]

Bruno:

>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 ones.

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

I'm reminded of the little green Simca 1000 two door coupe' I saw yesterday
while riding in the Wisconsin countryside.   It was perfectly restored and
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 using
the gears like a road racer just to keep up with traffic.  The car could not
have weighed much over 1500 pounds.   I chose the cafe in this town for my
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 and
lots more in sweat equity.   What a deliciously impractical way to spend time
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".  It's
not what one thinks of as a collector car, like a Jag or Ferrari.  It was,
however, one of the most attractive cars I've seen in a long time.   No A/C
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 cars
seem to be made beautifully inside and out.  I don't always agree with the
German preference for the occasional whimsically over-complicated solutions.
The new servo brakes are one recent example of that.   I've adapted to them,
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 transport
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 with
BMWs Valvetronic valve system?   I happen to think that system would be the
ultimate answer for a boxer bike.   No more throttles, no more heavy
valvetrains, cams and chains.   Seamless electronic control of valve timing
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.    I've
always felt this would be the right solution if the belt could be enclosed
without adding a lot of weight or hurting asthetics too much.   I've admired
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?    How
does it compare with a chain in that respect?

- -TB

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