I stand corrected.  Courtesy of Trike Asylum, I recently learned of a (nearly) production trike that meets most of my criteria for the “ultimate human-powered touring and commuting machine.” 

Update:  I stand corrected again.  I’ve now talked with the man behind the TRIOT, Martin Rassmussen, and can clear up some of the speculation that follows in this blog entry.  First of all, the front crank is indeed driven by a chain.  But not just any chain, a special high strength, high mileage “diamond” chain that is designed to run very quietly without periodic lubrication.  Combined with the truss that is the parallel boom, Martin says the result is a very quiet, clean, efficient, and maintenance-free drivetrain.  I don’t feel quite so bad about my original, incorrect assumption that this was a completely belt-driven drivetrain because that truss was designed to provide the required rigidity.  But until availability improves for belt lengths, the chain will have to do.  With the special chain, the enclosure, and a mechanism for precisely tensioning the chain that is independent of the leg length adjustment, they may have achieved much of the benefit of a belt anyway.  Martin gave me a bunch more information but instead of regurgitating it second-hand I’ll wait until I’ve had a chance to take a ride on one.  This will definitely be worth another road trip to Salt Lake.

The TRIOT is being developed near Salt Lake City, UT.  It’s a sophisticated design and the first I’m aware of that includes belt drive!  It looks like they solved the suspension problem by putting a mid-drive at the pivot point of the rear suspension, so the belt length remains constant.  They also combined the boom with an enclosure for the front belt.  At least I think that’s a belt in the front—you can’t tell from the pictures and their blog talks about an enclosed chain.  It’s definitely a Gates belt in the rear.  I’m guessing the enclosed “parallel boom” design also addresses the problem with boom flex and belt drive.  And it looks like they provide adjustable leg length by moving the crank along the parallel boom, somehow picking up the teeth in the belt anywhere along the boom.  Pretty ingenious if that’s how it really works.  But the more I think about it, the more this looks like an enclosed chain after all.  I don’t see how they could get enough wrap on the front sprocket without adjusting the length of the belt/chain to account for leg length, which is one of the killer design problems for an all-belt-driven tadpole trike.

From my original criteria, the only thing the TRIOT “lacks” is electric shift, a 20” rear wheel, and, well, lack of suspension.   None of these shortcomings are inherent in the design though—this thing is proof that I can have it all, at least in theory.

Yes, like most high-end trikes these days it’s fully suspended. I wonder if the manufacturer would see much value in removing that feature to make a lighter, simpler version of the trike.  It also has the popular big rear wheel—it would probably require some minor design tweaks to accommodate a 20” rear wheel.  Sometimes you just can’t buck the popular trends I guess.  The final shortcoming for me is lack of electric shift but that might be easily remedied by retrofitting the Rohloff electric shift option.

The TRIOT is intriguing but not a slam dunk for me.  In addition to the issues mentioned above, it’s relatively heavy (starting at 43 lbs) and sits higher and more upright than I prefer.  Still, the weight is less than some trikes with far simpler and less interesting designs.  I think this thing may create a new category of expensive, though at their projected starting price of $5,499 it’s well in line with cost estimates I’ve made based on the ICE trike.  I’d love to see one in person but based solely on their web site I’m quite impressed, even if they are still using a chain in the front.

Here’s to spectacular success with the new TRIOT trike.  So much success that they can build up their fleet with designs targeting touring and speed.  And usher in an arms race for belt driven tadpole trikes.