Adam Clark

I have been running a singlespeed mountain bike for quite awhile now, and have been experimenting with the pros and cons of different chain tensions. My friends have given me different opinions on the matter as well, compounding my confusion. If it's too tight, the drivetrain will wear prematurely. If it's too loose, it can damage the teeth on the sprocket and/or chainring. I hoped I would find closure by looking at examples of the myriad s/s 29ers from Dirt Rag's coverage of the North American Handmade Bicycle Show, but no dice: some had droopy chains yet others were high and tight. Advice before I kill my hub or break some teeth?

AEO

if it's too loose, all it does is increase the chance of popping off at a most inopportune time.

When at the proper tension your chain should only move vertically by around 3/8in to 1/2in when you lift it with your finger or tool.

Adam Clark

3/8 to 1/2. Is that from the chain's resting position upward?

AEO

when you lift the chain from its resting position, yes.

BCRider

And try this at various points of crank rotation for a couple of turns. Look for the tight spot. You need to do it for a couple of turns because it's based on the combination of runout at both the front ring and the rear cog. So it takes a couple or three rotations of the cranks testing about 5 or 6 times per rev to ensure you don't have one combination where things suddenly bind up.

Adam Clark

Thank you, gentleman. I clearly had it too tight. Do you think I could have damaged my hub or BB?

BCRider

In the short term no. If you have been riding it a lot like this then you MAY find that some of the links of the chain have deformed and the chain MAY fail. But it would need to be overly tight to where you'd feel it while riding to do this. More likely it's 100% fine. When I was first playing with SS setups I had the chain much too tight. It was fine and free running until the runouts ganged up and then it felt like I had to pedal over a "stick stuck in the chain" type of pressure that ramped up and then snapped over the top. It made for quite a cogging like feel in the pedal. If you didn't feel that sort of thing then you didn't harm the chain at all.

fabry

To get the best results its obvious that the chain should not be very tight since this create more stress on the teethes and when its too loose you have chance of popping off most of the time.So to make a deal out of it make the chain atleast free but not loose.
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