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Old 08-14-19 | 12:28 AM
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79pmooney
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Joined: Oct 2014
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From: Portland, OR

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

All you need is a good routine. First, use a wheel with a hub set up with nuts, not a quick release. Get the proper wrench. Now, when you need to replace the wheel and set the chain tension:

stand behind the bike with your left hand on the chainstay and fingers around the tire. Pull the wheel hard both back and against the left chainstay. Tighten the right nut. Now center the tire and tighten the left nut. Lift the chain with the wrench. You would like to see it lift 1/8" to 3/8" above a straight, tight line. Next, lift the rear of the bike and spin the crank. See to it that at the loosest and tightest portions of several crank revolutions, 1/8" to 3/8" lift still works. If not, loosen the ight nut and tweak the tire a little right to tighten, left to loosen. Tighten right nut. Loosen left nut and center the tire. Spin the cranks and check again. Good? Tighten both nuts and ride.

Every bike is a little different on how far over you should pull the tire to the left to start the process. Once you have that dialed in, you will find the first tightening of both nuts gets you very close most of the time. (How much your chain loosens and tightens also make a big difference in repeatability. A lot of chain action (tightening and loosening) is a function of crankset and chainring roundness (and to a lesser extent, hub amd cog quality). Quality makes a big difference here. So does whether they were intended for single-speed/fix gear use or for derailleur bikes. That roundness makes a big difference here and very little on derailleur bikes. (In fact, out of roundness might even improve shifting.) So manufacturers have little incentive to spend time, effort and $$s to carefully drill chainrings accurately - unless they know it is going to singlespeed/fix gear use. Good track quality gear is a joy to own and set chains with.

You talked of setting chain "tension". I trust you know that the chain should never have actual tension on it except the upper portion as you ride (or lower portion as you brake. At rest, there should be visible sag both top and bottom. Pulling the chain tight is/was very popular with the fix gear hipster crowd in Portland. Also with the shops that sold hubs, bottom brackets and replaced sealed bearings. If you go to a velodrome, you will see a lot of very slack chains on very nice bikes. Now, they do not have bumps and we road riders do so we have to run a little less slack and poorer equipment means going tighter still so that the loosest portion of the chain cycle is acceptable, but still, we NEVER want to see fully tight.

You do not want a quick release because then you have to both set the slack and centering the wheel at the same time. And if you miss slightly, when you release the QR you will lose everything. With nuts, you can break those into two almost completely separate parts. You use the right nut to adjust the tension. Get it where you want it. Then use the left nut to center the wheel. Yes, the tension will change, but only a very little. And with a little practice you will get to know how much and you can (say) pull the chain just a hair too tight, knowing that bringing the tire to center from the left will slacken it a touch.

If you always use just one cog/chainring combination and your bike has dropouts, not track ends, you can set the dropout screws for the proper chain slack. Now all you have to do is push the wheel back to the screws and tighten the nuts. (Dropouts, those near horizontal slots that open to the front as used on older road bikes. Track ends are dead-on horizontal and open to the back. Used on all bikes made for the velodrome and near universal on modern road fix gears. Some of us have learned that on the road, dropouts make life simpler.)

Ben
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