[trikes] Greenspeed GT3 gearing choices.

[John Turvey]

On Sunday, October 17, 2010, at 01:30 AM, Ian Sims wrote (IN PART):
>
> It is also possible to swap out the rear wheel for one with a standard 
> hub which will take say a 11/34
> cassette, but this will require a long cage rear derailleur to use all 
> gear combinations, which could give you
> ground clearance problems on unmade roads, or if you retain the 
> standard mid-cage rear derailleur, you will
> need to remember not to use combinations like small to small, which 
> may allow the chain to drag on the ground,
> or large to large, if the chain is adjusted to tight, when you could 
> damage the rear derailleur.
>

I have an early Trice Micro which uses the same 16 inch wheel as the 
GT3 - it has a standard hub with 11 to 32 cassette, 52 and 40 teeth 
chainwheels and a Speed-drive, giving gears from 17 inches to 126 
inches, and uses a Sram medium cage gear mech.  The clearance below the 
rear gear mech in some gears is minimal - a puncture in the rear wheel 
can mean the clearance is negative (I have replaced the rear mech once 
already as the original was wrecked as a result of punctures on high 
speed descents, and previously had replaced the lower jockey wheel in 
the original rear gear mech).  The other problem I have is that the 
clearance between the tyre and the rear mech is also minimal 
(especially as I use Greenspeed Scorcher tyres which are wider than 
most tyres) - after a rear wheel puncture, the cage on the rear gear 
mech can be bent, so using the lowest gear can quickly shred the side 
wall of the rear tyre (I have done this three times now - I keep 
telling myself to check the gear mech is not bent or misaligned, but 
forget occasionally - only when it IS bent or misaligned!)