B"H
Hi Mike, Thank you for sharing your GTT experience. I'll
definitely will use shorter cranks.
Do I understand you correctly, that you don’t like
Dualdrive that much on your GTT and would like to replace
it with a regular rear wheel because the Dualdrive
accelerates slower, is less efficient going up the hill,
and creates problems in shifting?
Thank you,
Victor
> >
> >
> >>I'm considering SRAM Dualdrive 27 for a touring tandem
> >>trike with 20" drive wheel and two chain rings 30-50 on
> >>a 155mm crank. Does anyone have any experience with
> >>similar setup? I'd appreciate any advice on this matter.
> >
> >
> > I am just getting into the shorter cranks, though not on
> > the tandem. I love them. You will likely spin a lot
> > faster and not require as high of gearing as you might
> > otherwise, assuming your stoker also like high speed
> > spinning, but you will probably want to gear down as low
> > as you can because torque does seem to decrease a bit
> > with the shorter cranks. Especially on my 140's, the
> > 155's I also use are not nearly so bad.
> >
> > I have the old version of the Dual Drive on my 1999 GTT.
> > It has not broken down and left me stranded. I do
> > sometimes ride with a very powerful stoker and we can
> > cruise in the 18-20 range. It is heavy, very heavy
> > rotating mass. When I took the dual drive off another
> > bent, replacing it with a regular rear wheel, I was
> > faster accelerating and faster up hills. I would love to
> > replace it on my GTT.
> >
> > I have had far more problems with shifting the regular
> > part of the drive train than on any other tandem I have
> > ridden, DF or bent. The rear derailluer,a Shimano seems
> > unable to be adjusted to keep the chain on one gear. We
> > can be cruising along for a very long way, straight
> > line, smooth road, when for no apparent reason, we
> > shift, then return back to the selected cassette ring. I
> > am switching over to SRAM derailluers because I
> > understand they use a stronger spring.
> >
> > I really have to moderate my power, and even this stoker
> > too, or we will cause the timing chains to jump out of
> > phase. I can do this up to about 12-15 mph just by
> > trying to sprint. New chains helped a bit, new chain
> > rings a bit more. Alignment is critical for the boom,
> > and unfortunately, every time I transport my GTT the
> > boom has to come off.
> >
> > Under the grass is always greener department, my current
> > thought would be to build a good strong, maybe even a
> > non freewheeling wheel for the rear and devise a mid
> > drive system, something like Rotator uses, to get the
> > range of gearing I need. My fantasy holds that shifting
> > will be smoother with a wider range of gears for the
> > slow crawls uphill and the fast trips back down, will be
> > stronger because the wheel will be built without any
> > dish, or nearly so, and the drive train will have tandem
> > rated parts so the cranks can be in sync, allowing for
> > faster acceleration and better climbing. This doesn't
> > address the cranks skipping though.
> >
> > For that I think some kind of device that will
> > tension/guide the chain onto the chain ring would solve,
> > or at least, minimize the problem.
> >
> > All that said, of the half dozen or so other bent trike
> > owners I've talked to, I am the only one experiencing
> > these problems, so my fantasy solutions may not be of
> > any benefit to you at all.
> >
> > Any comments? Anyone?
>
> There is the da Vinci Independent Drive [TM] that could
> possibly be adapted to a GTT:
>
<http://www.davincitandems.com/dv2.html>.
>
> The Rohloff Speedhub 500/14 is rated for tandem use:
>
<http://www.rohloff.de/index.php?p=PRODUKTE/SPEEDHUB>.