Wednesday, August 24, 2011

RM-20 Rides Like New

I took the newly-built Sekine out on a good 40km ride across town, and boy- this bike can fly. It's amazing how fast 30-year old steel rolling on 1 1/4" rubber can go. Power transmission feels solid, even though the ride seems cushy. The steering holds a strong line, almost to the point of unresponsiveness. Somehow, it's easy to set up a quivering speed wobble in the steering; but just as easy to snap out of it. The bike climbs a bit slow, but is very stable on the descent. And despite a bit of sun-fading, that red paint still looks great.

21" x 22" triangle.

Fit is the biggest issue; but I knew when I bought the bike that it was a size small. The seat post is raised to the max height (but still 2cm too low), as is the stem; which as a result, makes the bars feel flexy, and the bike looks a bit strange. Even with a 56cm top tube, the 60mm stem makes me feel a bit compressed; I notice that when I'm in the drops, I have to scoot my butt back almost off the seat to feel comfortable. However, I can probably ride short to moderate distances with no problems, and the small size makes the bike easy to whip around. I'd prefer handlebars wider than the 39cm c-c Road Champions, but feeling narrow can be nice on the streets.

Shifting with down-tube levers took some getting used to. Always reaching down, gauging cable pull by touch while keeping eyes on the road, ears listening for trim. The rear derailleur has a little quirk which could be termed "soft shifting". As the cable is pulled, a small spring-loaded arm on the derailleur body swings into contact to make the shift. This small, initial pull gives a mushy feeling at the shifter for a moment before engagement- I think I'd prefer a straight pull. Obviously, deft shifting will only come from practice, and the system is beautifully light and simple. Also, I will apply some thread-lock compound on the shifter adjustment screws, as they kept coming loose.

The gearing surprised me with its versatility. With a big 52/42 ring up front, the bike definitely likes speed, but this is balanced by a generous 14-28 range in the back. The big ring is actually useful around the city. Climbing the hills around Vancouver's bike routes, I definitely appreciated the 28T, and can see why old Sekines sold with this range may have been popular here. Long term, I'd probably switch the 42T for a 39T ring, just to add a bit more low-end for days when I'm tired.

Braking is probably the biggest concern with this bike. Going fast is thrilling, but it's more frightening when I know the brakes have a sluggish response. As mentioned in the re-build post, the brakes are Shimano Tourney long-reach side-pull calipers, which I have tried to augment with nice road cartridge pads and compressionless housing. Stopping is still more of a gradual affair that I'd like (compared to the disc brakes I'm accustomed to), however it's probably as good as it can get. Worst of all, after initial set-up, the rear brake caliper howled a painful vibration that travels up through the frame, buzzing one's genitals unnervingly. This is a clamorous problem, and I'm attempting to quell it by experimenting with the adjustment of the brake's center pivot nut (Update: setting the pivot a bit loose made a large improvement).

New tires, saddle, and bar tape make a big improvement.

On the initial quick test ride, the chain seemed prone to skipping off the rear cogs. Closer inspection revealed that this was probably due to insufficient chain wrap, caused by a weak derailleur pivot spring. My solution was to remove the dropout spacer inserts, moving the axle to the rear of the dropouts, and further past the derailleur pivot. So far this has eliminated the problem, although giving a 1cm longer wheelbase.

Overall, the bike is fun. It's exciting to ride something I've only looked at for so long, and it's strange seeing the bike parked in the house. It's red, chromed, silver parts, and pretty. I can't wait to take it out again tomorrow.

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