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TIM'S BIKE FRIDAY
NOTE: As of 2007 the Pocket Pilot has been superceded by the Pocket Rocket Pro with a Titanium Seat Upgrade.
We asked BF Customer Service Rep Tim Link about his racing Bike Friday based on a Pocket Pilot (note, this configuration is not standardly offered by Bike Friday, but is described here in the interests of showing an application of the new Capreo gearing):
My bike is a Pocket Pilot, racing green, with a titanium seatmast and a near full compliment of Shimano Dura-Ace components. The front hub is an American Classic for its light weight, and the rear is a Shimano Capreo for it's superb functionality with small wheels. I've set up my front chainrings for half-step gearing (see below).
What's so good about a Capreo?
* Goes all the way down to a 9 tooth cog! This means I don't have to have giant chainrings to get high enough gears for racing.
Why wouldn't I want larger chainrings?
* Front derailleur designs aren't optimized for shifting larger chainrings, so shifting performance is compromised a bit. With standard sized chainrings shifting is smooth and precise. A dropped chain during a race is highly undesireable.
Why half-step gearing?
* The Capreo is actually a wide range cassette, even though it's largest cog is only a 26. The ratio of 9-26 is equivalent to an 11-32, which is a much bigger spread than almost any road racer would normally use. So the Capreo gives me all the range I need by itself for road racing. I don't need an extra chainring for lower gears. The problem is that as a percentage, the gaps between gears, i.e. 10 to 11, or 23 to 26, are quite large. For road racing, it is preferable to have tighter spaced ratios between gears. I achieved tighter ratios by using a 50t and a 53t chainring. This way, when I switch chainrings, the effect is roughly half that of the effect of changing a cog in the back. If I want to go up a tiny bit and I'm in the 50t ring, I can just switch to the 53. If I want to go up again, I switch back down to the 50t and to the next smaller cog in the back.
If I want to shift down a tiny bit I switch down to the smaller ring, or if I'm already in the smaller ring, I shift to the larger ring and the next larger cog in the back.
It sounds a little complicated, but I've found it very easy to take advantage of in practice. The front shifting is very fast and smooth since the chainrings are almost the same size. With STI levers it's easy to simultaneously shift front and rear. (Well, with a little practice, it's easy.)
My bike currently weighs 18.75 lbs with saddle and pedals. It will get a bit lighter once I have a chance to upgrade the rear wheel to an M14A rim.
I have my seatpost on backwards right now to move the saddle forward for time trialing. I may be able to leave it backward by sliding the seat all the way back when I'm doing normal road riding. I'll have to see in the next few days of riding if that will work...
Tim timl at bikefriday dot com
 Service with a smile: Tim Link specializes in reconditioning Bike Friday pre-owned bikes. |
Emailable link to this article: http://www.bikefriday.com/bf/capreo-pocket-pilot
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