Friday, May 6, 2011

Fixie Chain Maintenance

Basically the chain should be tight enough to engage the sprockets without binding (too tight) , or skipping (too loose).


For maximum forward and reverse pressure control, you want the chain to have a slight ‘pre-load’ against the teeth. You can guestimate this very easily by checking the slack at the center of the chain . It should be about 10 – 15mm.

Now this is only part of the task. Because chances are, neither your rear cog or front chainring are perfectly round and centered. So, you will generally have a tight point and a loose point in the chain. So, the next step is to center the chainring. We can do this by un-tightening the chainring bolts just so they are lightly snug, then we rotate the crank slowly until you have the tightest point. Then what I do is take my handy peanut butter wrench and tap the chain in the middle a few times. If there is enough slack in the chainring bolts, you should be able to get an ever-so-slight reduction in chain tension. Then tighten the bolts back up following a star pattern (imagine you are drawing a star in a single stroke – that’s the order you should tighten your chainring bolts).

Then repeat the above process a couple times. This will get you very close to a perfectly centered chainring and consistent chain tension as possible.
After you’ve done this, then go back and check the overall chain tension again. For longest wear and least stress on the bearings, its best to run just a little on the loose side. But for best fixie control and pedal response, its best to run it just a bit on the tight side. I typically run my chain tighter on the track than I do on the road – but its a very slight difference.
One tip when tightening chain is to hold the wheel firm and slightly offset from center – maybe 2-4mm, then snug the axle nut. Then push the wheel to center and tighten the opposite axle nut. This will let you ‘rock’ the chain into a slightly tighter tension easily. Especially if you are not using chain tugs (recommended), or have worn dropouts that make it hard to get an exact placement for chain tension.


That’s it for now! I’ll be posting some more basic maintenance tips as we go along. During this exercise I found that my KMC NJS chain was stretched irregularly resulting in more tension variance than I prefer. So, I swapped my chain back to they trusty Izumi Super Toughness and all is good!
(roadfixie)

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