Otherwise, this tool should serve the average commuter well. Specifically, we think you’ll find the size 4, 5, and 6 hex keys, extremely common sizes in bicycles, very helpful. They’ll adjust seat-post heights or let you remove the saddle entirely, or tighten a loose stem that’s always rattling apart. The Phillips head will tighten loose bolts on shoe cleats or the rear derailleur. The most common use for the torx would be adjusting disc brakes if you have ’em.
First, I researched. I looked at Amazon’s top-rated products and their user reviews. Then I consulted Bicycling magazine, Gear Junkie, Bike Radar, Outside, and the occasional bit by Lennard Zinn via Velonews. I also found some worthwhile discussions at Bike Forums. Then I spoke with four experts, Ramona Marks, Scott Karoly, Cari Z, and Alison Tetrick, riders from all across the spectrum, who tour, repair, and race.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.
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