About two weeks ago I was hanging out at Books-A-Million with my wife, slurping coffee and checking out the October ’11 issue of Bicycle Times magazine. I came across an article on pg 65 describing the FSA Metropolis Patterson Bike Transmission, and as I read it I realized it would be perfect for my trike.
I have a TerraTrike Path 8 that I purchased used. I love the trike, but the wide range of the Sturmey-Archer XRF-8W 8-speed IGH wasn’t quite low enough to get me up some of the local hills, and still have enough top end for normal use. I had remedied the problem by installing a 24/42 double crank with a front derailleur and twist shifter, and an old rear derailleur on back to wrap the extra chain. Actually I tried a chain idler on back first, but found the derailleur was able to tune the chainline more precisely.
This setup worked well enough. I even rode a 55-mile loop on it that included hills I would have only attacked with a granny ring on my wedgie bike. But it had the disadvantages of still requiring front and rear derailleurs even though I was using an IGH. And the rear dropout wasn’t made to accept an idler or derailleur, so I had to kluge together an external derailleur hanger arrangement that would not interfere with my IGH’s dropout washers. And the front shifting was a bit stiff.
The article I was reading described the Patterson crank as a two-speed with 1:1 and 1:6 gear ratios, producing an effective 28/45 crankset. Wow, I thought, that is almost exactly what I’ve been using! As I read on, I learned that the Patterson crank installed like a conventional bottom bracket, no frame chamfering or modifications were needed, differing from the popular Schlumpf Drive. And the best part is that the price was only $299 MSRP, hundreds less than the Schlumpf. How could I lose? Okay, there were a couple of disadvantages. First, there were no options to change the chainring size, so I would have to like the gearing. This was no problem, the gearing was almost exactly what I had. Second, I had to order a couple of tools I didn’t have for the installation, and that would add $30-40 to the cost. Okay, I’m a guy, when was ordering another tool ever really a problem?
I was totally stoked by the time I went home, but I knew I should do more research. It turns out I couldn’t find anyone who had used one of these yet except for a mountain biker on the pattersonbike.com website. Obviously that seemed like it would be less than objective. And I also learned that I could order the crank from bikesonline.com for $237 with free shipping ($267 with the necessary tools included). I also checked out the excellent installation video at pattersonbike.com and decided this was worth pursuing. The printed installation instructions that I also downloaded included a strong recommendation not to use the crank with a front shifter with “click stops” – basically, one that is not infinitely adjustable between its end stops, as I read it. I figured the grip shifter would work, but I decided I would look for something better. I ordered the crank.
The goodies came a few days later, and I began the installation. I was concerned that the chainstay stop might not reach in far enough to rest correctly against the TerraTrike’s frame tube, but I devised a plan before I ordered the drive. If needed, I planned to remove the stop and put an aluminum spacer behind it, with holes drilled through it to pass the two screws. Of course longer screws would be necessary too. I think the screws and aluminum bar stock could be obtained easily at a hardware store. As it turned out, the stop protruded enough that this was a non-issue.
The second issue of concern was the direction of cable travel. I took care of this by purchasing a clamp-on cable stop made by origin8. Since the cable actuation had to come from above, I simply dressed the housing to loop up from the boom, then face down in parallel with the derailleur riser. This worked out quite well. Since there were no pre-existing cable stops for the FD, nor an OEM FD cable, I had lots of latitude for creativity. The cable stops are available for different diameter tubing. Here is an example on Amazon http://www.amazon.com/Origin8-Clamp-.../dp/B003BC7MZK
The third issue was the front shifter. I found the Shimano A050 shifters designed to be mounted on road bars on each side of the stem. These shifers only cost about $20 for the set (shipping included), and met my needs beautifully. If you already have bar ends, this is a non-issue for you. http://www.amazon.com/Shimano-Handle.../dp/B001L5Y1GC
Since I installed the crank I have had it out on one 30-mile ride, with more “testing time” over the next few days that should include more hills and dales. So far I have experienced no issues or concerns with the drive, and have been quite pleased with the result overall. You can check out pictures of the TerraTrike Path 8x2 (before and after installation of the Patterson crank) at https://skydrive.live.com/?cid=c5295...1337&sc=photos