Archive for September 10th, 2008

20080910 Bicycle Maintenance

Wednesday, September 10th, 2008

This post isn’t very exciting unless you’re fascinated by bike parts. I’m mostly posting this for reference.

We had a number of packages delivered to us in Fredericton, including one from Rohloff which contained two new 17-tooth rear sprockets and a tool to change sprockets. This and the 6 chains we ordered through Radical Edge (a bike shop in town) allowed us to correct our chain stretch problems. Unfortunately, when Scott compared the old sprockets to the new, he discovered the old ones were 15 tooth. If we did a direct replacement, it would mess up the gear ratio (currently 36/15 – 2.4), but fortunately we had a couple of 40-tooth front sprockets in the resupply gear Mom & Dad Drennan brought. That brought the gear ratio back to 40/17 = 2.35 – quite acceptable.

The new chains and sprockets are much smoother, and hopefully the combination of better chains (SRAM 870 instead of 830) and larger sprockets will allow this chain to last longer than the last one.

Our odometers are only reading 4200 km, and an oil change isn’t due until 5000, but we had the kits (and didn’t want to carry them), so decided to change the oil now. We’re glad we did, the hubs seem to be running much more smoothly. We have read elsewhere that as the hubs age they get smoother – hopefully this is the start of that process.

We also tested out the emergency rear shock replacement Scott’s Dad built for us. It’s a bar of aluminum with two holes for bushings, and four bushings made of Ultra-high molecular weight polyethelyne. The dimensions are designed to match the existing rear shock, but it’s rigid, so doesn’t do much to soak up energy over bumps. The important point is that It is much lighter than a spare shock, so we can carry it without too much trouble. Thanks Dad!