Silver Case

We leave for three weeks in Italy a week from Tuesday. I’m trying to put our bikes ready in time. I built 406mm wheels for Le Chacal and repaired the headset on the Dahon.

Once I started riding Le Chacal on my daily commute, instead of my 700mm titanium racing bike, I realized how absurdly low-geared it is. Small wheels plus the stock MTB gearing set on it leaves me with way too many ultra-granny gears (full cadence 90rpm pushes me at normal walking speed!) and not enough high-end to go fast.

So how to fix it? The rear cassette is 11-32. 11 is about the smallest cog you can get without getting into the strange Shimano Capreo transmission system. I don’t want to go down this route because Capreo is hard to find, it uses special tools, and defeats some of the simplicity-of-repair I want for the bike. Then what about replacing the 44-32-22 crankset with bigger rings? Again, turns out these are hard to find and I couldn’t get something big enough to make a difference.

It turns out the best thing to do it just toss the crankset entirely and replace it with a road set, like Shimano Ultegra 53-39 double-ring. That combination loses some of the uselessly-low granny gears and earns me a few higher gears. I’ll still be able to spin them out > 40kmh, but it’s definitely going to be faster.

This chart shows my current gearing (Le Chacal Current) and my race bike gearing (Tri Current) versus the new design (Ultegra 53/39 + 11-34). Main differences: Highest gear at 90rpm cadence gets me close to 40kmh. I sacrifice most of the <10kmh granny gears. And since I have fewer cog combinations, the spacing at higher gears is fairly wide.

This should do, and Ultegra or comparable hardware is easy and inexpensive to get hold of. The problem, however, is that my bike’s cable routing is setup for a MTB-style derailleur — the cable comes from the top of the bike while road bikes expect the cable to come from underneath the bottom bracket. Bad news. What can I do that doesn’t involve welding on new brazeons? Turns out a German company manufacturers a little addon lever that I can bolt on to the derailleur which converts it to a top-pull operation. I don’t know how long it will take to get this piece.

Most signs point to me bringing Le Chacal to Italy in its stock configuration unless by some miracle Speen can airmail me this part in just a few days. And if not, who cares. My high gear still runs at 33kmh, and as proven, this is the max speed I can maintain continuously for an hour, so I can live with it. The bikes are here for leisure anyway, not hard riding. Plus I wonder how my gearing compares to Le Chacal, which Matt will be riding. Fortunately, they are matched pretty well, in fact the Dahon is geared a touch faster.

This entry was posted on Sunday, September 6th, 2009 at 7:40 pm and is filed under Dahon Mu XL Folding Bicycle, Le Chacal.You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.