Custom gears...

[omgwtfbyobbq]

Well, just one actually. Does anyone know what would be involved in making a much lower 6th gear for a motorcycle? Something that would cut engine speed in half compared to the stock 6th gear.

[GasSavers_Bruce]

I'd suggest trying a smaller sprocket on the rear wheel first. It's a lot easier and cheaper to change out, so you'll be able to dial in the top end a lot more quickly for lower cost.

It also has the advantage of changing all the ratios instead of just one, so there'll be less of a jump in engine speed when you need to downshift for an incline at speed.

The tradeoff is that first-gear acceleration won't be as quick.

[omgwtfbyobbq]

Unfortunately the bike I had in mind is shaft driven, so I figured it'd be easier swapping out 6th than it would be to fiddle with this. And, like you said, this would hurt acceleration for all the other gears as well.

[thisisntjared]

Originally Posted by Bruce

I'd suggest trying a smaller sprocket on the rear wheel first.

i agree. in theory every gear will not be as quick, but it is definitely a lot easier and cheaper

EDIT: i would get a different bike in mind

[omgwtfbyobbq]

But it's free! FREE!

[red91sit]

I have the same situation. 60 mph in 6th gear is a mind boggling 5000 rpm!!!! I don't want to get a higher geared setup, because it's 1st and 2nd are plenty tall to start with (wheelies are a bit tricky)

[skewbe]

Shaft Drive you say? Overdrive unit then

[omgwtfbyobbq]

Hmm... Interesting. I have no clue how I would make one of these, but my uncle's been studying transmissions, and can make anything. Thanks for the info!

[Silveredwings]

Originally Posted by skewbe

Shaft Drive you say? Overdrive unit then

That would work but it may be quite a project (I get it ). The thing is a planetary gear system about the size of a watermelon with an electro-hydraulic clutch, and weighs almost as much as a transmission:



It has to remain spinning fast enough to make atleast 400 psi of oil pressure in order to operate (usually shares its oil with the tranny). A quote from elsewhere on this site regarding the Laycock De Normanville OD:

Let’s think for a minute why overdrives were put in cars in the first place. I mean after all, anyone can put in a 5th gear on a transmission, why an overdrive? First of all the British never do anything the way we expect or anyone else does it. This was especially true in the 40’s, 50’s and 60’s and is why we have such interesting cars from that period. Laycock overdrives are really like a manually initiated mini automatic transmission. (I personally think a guy named Rube Goldberg had a major part in their design). The important thing to remember is that it was added as an option on most cars in order to reduce engine RPM (and consequently wear) on the highway and increase fuel mileage.

YMMV

[omgwtfbyobbq]

Jesus that's big. I may be better off with a one off sixth gear... Course I don't even know if it's doable until I crack open the tranny.