Thursday, August 2, 2012

Let The Patterson Transmission Enhance Your Commute

Patterson Transmission cranks installed on a Raleigh ten speed re-purposed for all season commuting.

   Here at The Hub we love commuting and since commuting and internal gears go hand in hand, why not talk about FSA's new 2-speed internal crankset the Patterson Transmission? FSA is a relative newcomer to the world of internally geared cranksets, with both the Schlumpf drive and the Hammerschmidt having been on the market for some time. The difference, for myself anyway, lies in accessibility.
   I haven't been able to justify spending the money for internal cranksets in the past as both the Schlumpf and Hammerschmidt retail in the $700 range, so i was pretty excited when the patterson came on the scene at far more reasonable $300. I bought it, set it up and have been happily riding ever since.
   First off, i guess it makes sense to talk about what type of bike this belongs on. the important physical restrictions are simple, the bike must have a 68mm bottom shell and fixed chain stays. you need to have down tube cable routing, but if you don't you could always add a clamp on cable stop, so no need to worry about that. This crankset was designed by Sam Patterson (one of the founding members of Sram) for commuting, but could easily find a home on a touring bike, mountain bike, weekender recreation bike or cargo bike.
Bottom bracket shell faced to exactly 68mm with perfectly parallel faces for optimal bearing performance.

  A few things to remember when picking one up. Installation has many facets as you need to have your bottom bracket shell faced (to ensure 68mm which and to give the outboard cartridge bearings a good reference), you need to pick out what shifter you want to use and have that and a cable installed (not included) and you need a few specialty tools (we would be more than happy to install it for you, inquire about service rates at the shop).
   Now for the fun part; what's inside and how does it work?
    Anyone who is familiar with the Hammerschmidt will recognize the similarities right away, a simple planet gear system with a direct drive and an overdrive. The crank's direct drive functions just like any other crank (the Patterson comes with a 28t ring) and the overdrive increases the gear to the 1.6:1 ratio. This effectively gives you a 45t ring!! 
Initial diss-assembly of the crankset.

The function is simple: operate the shift lever to release cable tension and the pawl on the control plate sub-assembly engages a ratchet in the crank which in turn...

...rotates the sun gear, which then rotates the planet gears, and they, in turn, rotate the chainring section of the crankset faster than the crank is spinning. And...

...voila, simply 2 speed planetary gearing!

   Impressions of the crankset so far are very positive. The shifting is super quick and clean (i have mine set up to an old Sturmey Archer trigger shifter). The gear range is wide enough but the jump is reasonable so i don't end up with a lot of annoying recovery shifts (I have mine set up with an 8 speed Shimano nexus rear hub, f.y.i.). the bearing set up is FSA MegaExo, reliable and serviceable.

The cartridge bearings are easily replaced when worn or easily serviced on a regular schedule to maximize their lifespan.

I am one of those mechanics that really appreciates the value of a good overhaul so i clean out my cartridge bearings a bit more often than most, and i have to say, it does increase the lifespan. The non-drive side cup is your typical MegaExo setup. The drive side is another story

The bearing is connected to the crank via a small snap ring and the cup remains empty in the frame.
FSA uses completely serviceable cartridge bearings which can be easily broken down to the loose balls for thorough cleaning and bearing ball replacement.
The picture isn't great, but here we have clean races and fresh grease with brand new bearings.
Align the new bearing balls, re-install the retainer and seals and you are ready to ride!

The chainring is a bit different than the usual fare, as well.

The chainring is held in place by a splined interface
It is held in place by a spiral retaining ring
    Replacement chainrings are available at a reasonable cost, which is good news for winter riders who tear through drivetrains, and for those who prefer to ignore maintenance on their ride until it's pretty much destroyed (though, i would always still recommend regular maintenance to prevent parts from wearing prematurely). FSA also makes replacement parts available for most of the internals, which is good news as nothing lasts forever. And speaking of maintenance, the above photo gives a good illustration of the ports that allow easy access for flushing and lubing the internals with minimal diss-assembly! this keeps maintenance easy and hassle free.

   Final thoughts... The Patterson transmission is going to make the internal gear set pretty excited. With the most affordable 2- speed crank currently on the market there is no reason not to double the range of your internally geared commuting bike, so you can find better gears and ride more efficiently, which means having more fun. Reasonable cost, 165-170-175mm crank length options, 9 speed compatible chain, mountain bike approved... whats not to like?