It is possible in some cases to eliminate or at least shorten the chain tubes on some Catrikes. It usually requires moving or adding an idler wheel. Terracycle makes some that clamp around the frame. Usually the reason you can't completely eliminate the tubes is because the idle side chain will make contact with the cross member. Keep in mind that as the boom extension changes, so does the chain line.
Flaring the ends of the chain tubes (particularly where the chain enters the tube helps some. Also make sure the alignment of the tubes ensures that the chain isn't hitting the entrance/edge of the tube. HTH
Yeah....Did all the above but the chain wore right through just beyond the flare! Disassembled, reflared readjusted....and a few hundred miles later I am starting to hear the grinding noise on the power stroke again...Really annoying. I thought about adding an idler but hate to spend another $80-$90 on just the bracket. And the TerraCycle idlers are priced like they are pure gold!
Guess I better talk to UtahTrikes....
Rans Screamer, Catrike Expedition, Specialized Montain Bike, Cannondale Quick SL1
I have a 2012 Expedition and I did the change over to Terra-Cycle idlers for both drive side and return. As a result, I was able to eliminate all but 4" of tube on the return side where the chain crosses under the cross-member. Here's a thought. The sport idler that comes on the Catrike is an aluminum cog. We wore one out after about 500 miles on our recumbent tandem, (Rans Screamer) so I switched to the titanium cog for $14. Relatively inexpensive upgrade, and the drive train is very quiet. I'll do the same thing with the Catrike when things get noisy. Just a thought, but perhaps you've worn down the teeth on the aluminum cog on your Expedition and hence the noise. Mike
I can't speak for the specifics of an Expedition, but I have a Greenspeed power idler on my Baron. It has plastic teeth, and shows no wear to speak of even after 15000+ miles. Toothed power idlers just don't wear like cassettes and chainrings do. Chains do Bad Things to flat-bedded belt pulleys, though.
I had the same issues on my Trail. I HATED the chain tube noise and knew it was costing me something in effort. So, when I put on the adapter and the 26" rear wheel, I also got a 'power side' idler from Utah Cycles and installed it. Additionally, I cut down to chain tube on the return side to about 3" where it wanted to rub the frame under the seat. The result was a VERY quiet chain, and better transmission of power to the big rear wheel. Utah also sells a return side idler, to eliminate any chain tubes at all.