Fixed gear drivetrain issues
 

Hi guys, new to the forums here, but i've been lurking them for a while. I'm not new to cycling but riding fixed is a relatively new thing to me. I just have a couple issues with my bike and i'm wondering if they're related/how to go about rectifying the issues. First off, I should say I have an SE Draft Lite 2011. Yes, I know they're pretty much **** but I was aware of that when I bought it. Wasn't 100% sure how much enjoyment i'd get out a fixed gear (rode a friend's fixed a couple times and liked it but didn't ride it enough to really get a good feel for it) so I didn't want to blow the bank on a bike I would possibly quickly lose interest in. Well i've absolutely fallen in love with fixed gear riding and it's totally renewed my interest in cycling, so now the bike is serving as a "jumping-off point" to build up a much better bike and eventually replace the frame itself. It's pretty much stock right now, apart from some Time ATAC XS pedals I recently installed. So that's where i'm coming from here. ANYWAY, on to the problems:

1. An very noticeable un-evenness in chain tension that seems to be un-correctable with the current components. I tried the whole Sheldon Brown fix (loosen chainring bolts and retighten them just finger tight, find crank position where chain is tightest, strike chain, etc.) and while it appears to work initially, after I re-tighten my chainring bolts the un-evenness returns. I noticed my chainring is slightly bent (i do mean slightly, less then a millmeter of total side to side movement while turning cranks, very hard to see.) Is this the reason for the permanent uneven chain tension? I'm installing an All-City 612 track crankset and a compatible bottom bracket+spindle in the next couple of days here so if the chainring is the issue it will be fixed when the crankset is installed. I'll probably also be getting a new, strong 1/2" x 1/8" chain when the cranks are installed, because why not, i'm sure it'll be better than the stock chain.

2. Rear Axle slipping in dropouts. No matter how tight I crank down on the axle bolts (i've tried different 15mm axle nuts, such as track nuts with floating washer, as well as what are essentially track nuts, only with the washer fixed in place, welded to the main part of the nut), 20 minutes later on the next ride, lo and behold, my wheel has slowly shifted forward (the wheel does indeed stay centered between the seatstays and chainstays however) in the dropouts and the chain is noticealby looser than when I started the ride. Possible fixes to this? (i'm not interested in a chain tug, if other people can hold their wheels in place without them, they seem more like a symptom reliever rather than an actual fix to the problem at hand)

Could issues 1 and 2 possibly be related? I experienced the uneven chain tension and wheel slippage problems only after noticing the chainring was bent.

Any help would be greatly appreciated.

Not to have you guys do my homework for me, it's just that I feel i've tried everything I currently know how to do and i'm kind of at a loss here. I just want to get back to riding ASAP. Go easy on me, i'm new to DIY bike repair as well!

The two problems may be related. Many low-quality chainrings and cogs are considerably less than round. If your chain is too tight to begin with, when the "tight spot" on the chainring comes around, the chain will bind and inadvertently try to force your axle forward regardless of how tight your track nuts are.

If you've tried centering your chainring to no avail, you'll need to get a better one to fix the problem.

Thanks for the speedy reply, I figured the chainring might be the cause of all this but I really wanted a bit of confirmation to steer me in the right direction. As far as binding goes, will you definitely know if your chain is binding? I don't really know how to spot it because i've never had to deal with it before. Even with the issues, the drivetrain doesn't seem to encounter much resistance while in motion so i'm not sure if there's any binding going on at the tight spot in the crank's rotation, although I will agree the chain probably is at least a bit too tight at that tightest point. The All-City 612 comes with a 46T chainring and people seem to think decently highly of its quality so hopefully that will fix the issues.

I'd replace the rear cog with a good quality one while you're at it because, as Scrod commented, both the chainring and the cog could be out of round.

As for the chain going loose, if it just loosens up and stays there, ignore it provided it isn't dangerously loose. You may find it goes away with the new drive train anyway.