BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

As I say in the linked article, when I got my 04 last summer and started getting familiar
with it, I found some objections to the tall 1st gear and the wide spread between 5th and 6th
and the result that had on driving on 2 lane roads where I do the vast majority of my driving.

Soooo - being the inquisitive type, I set out to find out if something could be tweaked to
improve on those situations. First I discovered the RTP transmission with it's low first
gear and more practical 5 to 6 spread, incidentally quite similar to the ratios in the much
touted R1200 bikes.

Doing a little calculating on rpm vs mph, I quickly found that swapping in the RTP trans
to help lower 1st gear would hurt my 6th gear upper mph rpm range, so then proceeded to
look into different available FD ratios. Being new dealer installed gears are quite expensive,
and looking for a challenge, I looked into alternatives.

Many of you will probly think I carried this to the extreme which I won't argue, but I've
found out an interesting combo and info along the way and, despite the seeming complexity
involved, ended up with a considerably lower cost and overall combined gearing very close
to that of the R1200's. And enjoyed the discovery process. When complete, I'll be able to
drive those 2 lane roads from about 53 thru 68 mph in 5th without shifting and while maintaing a
comfortable rpm, and still have nearly the same 6th gear mph / rpm for the freeway as the stock setup,
plus an admittedly minor reduction in 1st gear, although a reduction nonthless.
After all, isn't enjoyment what biking is all about?

For those of you who may be curious

http://www.mediafire.com/?gj1qdmm22tj

If you can't be kind, at least be gentle :-)

It sounds like the RTP trans shares the ratios with the R1150GS Adventure.
Lower 1st, not so high 6th.
I think you will find that the GSA is no slower in top speed than the GS, as the gear ratio allows the engine to rev free.

For my riding, I would like the lower 1st more than the worry of extra revs at highway speeds.
Unless you were riding at high speeds(80+mph), I doubt your fuel would suffer much.

From what I've found, they're the same trans.

The reason I started looking in the first place was the lower 1st gear.

However with the FD change, it negates much of the advantage gained in 1st
in favor of a really nice rpm / mph range in 5th and 6th, esp in 5th for 2 lanes.
Basically, shift it and forget it.

I don't like to run an engine at too high of an rpm unnecessarily. An engine has
only so much life - so many revolutions - built into it, and the stress on esp rods
and pistons / rings increases exponentially, not linearly, as rpm increases, esp
in higher rpm ranges. Plus generating more heat which is harder on the oil, so I
like to keep an engine in it's "sweet spot" when I can. I'm concerned with that,
not with a drop of a couple mpg.

We'll see how it goes after I get it back together.

What RPM do you call your "sweet" spot??
I wouldnt worry about wearing the engine out, it will probably outlast you

On that point, you're probly right! That bike will probly be running for years after I'm not any more.

It just seems to run so nice and smooth, without lugging and without higher rpm vibration,
between about 3k and 3800. I'm not talking about a short term blast into upper mph and
rpm, but a normal drive down a highway with the normal variations in rpm that lasts more
than a few minutes at a time.

I'm an old hot rodder, an ex-over the roader, have operated lots of small to heavy equipment,
and in general have many many years of experience with many different engines, and have
come to believe thru operating/driving them that each engine has an rpm range that is within
the design parameters of ports/valves/intakes/cam design - duration @ 050 - peak torque and
hp, etc. It's as much a thing of "feeling" how the engine is running thru long hours of experience
as anything else. When it sounds smooth, not lugging, and not laboring at excessive rpm.