For True "GEAR" Heads

[bdx]

I am not a gear head. I am a rider with sufficient mechanical skill to fix the small stuff and the ability to find a mechanic for the stuff I can't fix. Ever since I got into Adventure Bikes I have been curious about this.
RE: big bore adventure bikes. Is there a mechanical/physical/philosophical reason they don't have a super low "granny" first gear? It seems for the purpose these bikes are built that a low first gear would be a no-brainer. Make 2nd and 3rd about where 1st and 2nd are currently, then you could have a bigger gap to 4,5,6 for highway riding. I read all the time about guys trying to find a gearing that brings the low end down without sacrificing top end. For off-road riding, trails, tight mountain passes... I don't need a first gear that will take me up to 35/40mph. Not trying to be a smart-ass, I really know nothing about the inner workings of transmissions. Is this hard to do or is the inertia of years of manufacturing motorcycle trannies the problem?

[High Country Herb]

No, it isn't difficult to design them that way. I wish they would.

Wide ratio gear boxes (that's what you're talking about) don't drive as smooth, because each shift requires the motor to go from very high to very low rpm. Apparently most people don't like that.

The other reason is that really good riders just blast up hill climbs at high speed. I'm not that good on a heavy bike, so I tend to put along when off-roading, especially with the extra weight of a passenger sitting on my low profile 180/55-17 rear tire.

Along those lines: I'm currently researching new gear sets for my wife's Subaru Impreza. I think I will be using a WRX STi gear set that has lower gears for the first 2, and higher gears for 4th and 5th. This will be great for my super steep driveway, and improve fuel mileage on highway. Not to mention, they are stronger than the OEM gears used on our 2.5RS model. Win-win.

[troidus]

There may be a physical ratio limit related to case dimensions, shaft diameters, and shaft spacing. Maybe someone should create a bolt-on 2-speed planetary clutch.

[High Country Herb]

Originally Posted by troidus

There may be a physical ratio limit related to case dimensions, shaft diameters, and shaft spacing. Maybe someone should create a bolt-on 2-speed planetary clutch.

Good idea you've got there. Reminds me of the old 3-wheelers with the high/low switch.

[chollo9]

Unfortunately, because most people ride them exclusively on the street.

[RustyStuff]

Well some bike were made with Dual Range transmissions. Honda trail 90's and 3wheelers had this in there 2nd version, 1st one's had 2 sets of sprockets.

I also want to say that some big street bikes in the late 70's may have had dual range tran's.

I honestly don't know why they don't, I bet they would add alot of $$$$ to the price though.

[anotherguy]

Originally Posted by chollo9

Unfortunately, because most people ride them exclusively on the street.

Honestly it's because they work best on the street. Yeah I know some (few) can ride them well off road but it is not where they belong.

[Benesesso]

Agree with you that so many bikes are way overgeared. Old Huskys were great because some had wide-ratio 6 speeds;

If you don't want to use a big rear sprocket (I'm not a fan of small front ones), you'll have to do what so many riders do--slip the clutch a lot. Fortunately clutch plates are easily changed in many bikes, as opposed to cars and trucks and some BMW dry clutches (from what I've heard).

[xcflyn]

Originally Posted by anotherguy

Honestly it's because they work best on the street. Yeah I know some (few) can ride them well off road but it is not where they belong.

Really - "Yeah I know some (few) can ride them well off road but it is not where they belong" .

Not true at all - stop over by orange crush. It is more a case of people using them more on the road - not that they do not belong off road.

I think dual range transmission is out because of space & weight ? Hard to believe when looking at the big dual sports - but every ounce adds up. Most people, even hard core off road riders will still ride their big bikes over 50% on the street, and a close ratio is better on the street. It it a interesting thought- my GF Yamaha XT250 has a big gap between 1st and 2nd- it works just fine and that little turd has no power, you would think they could do better on the big bikes. Not sure about the new GS's but I know a few years back you could get a trans option ? Be nice if you could get a low first gear option on these big bike. Being chain drive sure helps make it easier to re-gear , I am up 3 in back on my 990 just to get it where I want it off road, it is still good on road but I dont travel long high way slabs at 90 so its fine. Contrary to the the comment the big bikes dont belong off road - mine spends more time on gravel, dirt, trails, even single tracks, then it does on the asphalt.

[chollo9]

Yeah, they belong wherever you want to go, just like those plated dualsports on the road.

[rapidoxidationman]

Yamaha WR450F?

Wide-ratio five-speed transmission uses strengthened gears and YZ450F-spec multiplate clutch—good for quick-hitting power in the woods, as well as eye-opening top-end power.

of course, it's only a 450...