I've been working this week on finishing Xtracycle number 2, a mid-90's GT Karakoram:
It's set up with a Surly 1 x 1 disk fork, Hayes disk brakes, Sun Rhyno Lite/XT wheels and Nitto Albatross bars. A pretty good combination so far.
The GT frame is not suspension-corrected, but the Surly fork is—which has a surprisingly positive effect on its handling. Large Marge suffers from the same heavy steering that many folks have said comes with stock Xtracycle conversions. I've measured the relative heights of the rear axles and Boss Hogg bolts (where the Xtracycle connects to the rear dropouts of the donor bike) and found that the GT has an axle height of 13 inches and a BH height of 13.625 inches. Marge also has an axle height of 13 inches, but her BH height is only 13.125 inches. One might have thought that keeping the Boss Hoggs at the same height as the original rear axle would be the ideal, but now I'm thinking that might not the case. It's hard to know whether the fork by itself makes the difference, but I'm thinking I might like to try the Surly fork on Marge (because I'd like to convert it to disk brakes anyway.) I'm guessing that raising the front end will improve Marge's handling much in the same way it has improved the handling of the GT.
There's also the issue of GT's frame design, which I like quite a bit in spite of its goofiness. It has a noticeably harsher ride which I hope will translate to improved torsional stiffness with a load of cargo on board. The Trek 830 (Marge) has a disconcerting whippiness at low speeds with a heavy load. The handling improves considerably once it reaches 7 or 8 mph, but I'm glad I've never had to make an evasive maneuver while carrying buckets of sand or the like.
And than there's the cable routing for the rear brake:
...which is just a bolt from a post-type cantilever brake, bolted to the seatstay bridge as a stop, with a barrel adjuster added as a ferrule. Ended up being pretty clean, really.
Now I just need to add a few little things like grips, a bell, and the Xtracycle racks to finish up. I'll post pictures of the final product...