Gearing question

I am currently in what I hope to be some of the final stages of
building a quad recumbent with independent rear suspension. I've
managed to tie the two rear wheels together but I seem to be having a
gearing issue. I start off at the front with a single 36T front
sprocket. This goes to a 7sp cassette pack with a standard coaster hub
sprocket attached to the other side. This connects via a short chain
to another standard coaster sprocket. This is on the axle that
connects my drivetrain together. On this axle driving my rear wheels
is a 36T sprocket on each end which was part of my original donor
bikes. This goes back to a 6sp cassette on each rear wheel. I know
this sounds complicated but it was the only way I could achieve the
gear range I was trying to accomplish. I belive my problem is going
from the small sprocket on the axle to the large 36T on each end. I
think this is causing a problem but no 100% sure. I have pictures
here. quadrecumbent.blogspot.com Any help is greatly appreciated.

Moose

Derick wrote:
I am currently in what I hope to be some of the final stages of
building a quad recumbent with independent rear suspension. I've
managed to tie the two rear wheels together but I seem to be having a
gearing issue.

snip


Moose

Moose:

You don't say what the gear range (# of teeth) is on your front and
rear freewheels, so I'm guessing a bit. If they both have a 28-tooth
big cog, your low gear is around 30". That's fine for a 20-lb race
bike! If you can find a MTB crank with a nice 24-tooth chainring you
can get down to about a 20" gear which should be OK for getting away
from a stop and general tooling around on the flat. If you're going to
offroad this beast, you'll want some *really* low gears. In that case,
I'd get a megarange 7-speed freewheel/cassette (depending on what kind
of hub you're using) and you can get down to around 17", and ideally
24-tooth chainrings at both the crank and mid-drive for about an 11"
low gear. For comparison, my Rotator Tiger has a 5-speed (originally
6-speed) mid-drive and a 9-speed cassette on the rear wheel. I've set
it up for a low gear of about 16", which is fine for hill-climbing on a
bike that will fall over below 4 mph anyway (at least with me on it).
For a trike or quad I'd gear lower, hence my recommendations.

Hope this helps,

John

P.S. Are you also Moose on BROL?

Maybe the analyzer at http://www.cycletech.us/gears/ might help you evaluate
your gearing options?


"Derick" wrote in message
...
I am currently in what I hope to be some of the final stages of
building a quad recumbent with independent rear suspension. I've
managed to tie the two rear wheels together but I seem to be having a
gearing issue. I start off at the front with a single 36T front
sprocket. This goes to a 7sp cassette pack with a standard coaster hub
sprocket attached to the other side. This connects via a short chain
to another standard coaster sprocket. This is on the axle that
connects my drivetrain together. On this axle driving my rear wheels
is a 36T sprocket on each end which was part of my original donor
bikes. This goes back to a 6sp cassette on each rear wheel. I know
this sounds complicated but it was the only way I could achieve the
gear range I was trying to accomplish. I belive my problem is going
from the small sprocket on the axle to the large 36T on each end. I
think this is causing a problem but no 100% sure. I have pictures
here. quadrecumbent.blogspot.com Any help is greatly appreciated.

Moose