So if you have raced in the bay area this season you have probably seen me drop my chain in the Single Speed category, at least once. I have done 13 races so far this season and have dropped it once in every single race except for 3 or 4. I got a new Rock Lobster a few races ago (kept same wheel) and thought this would fix my problems but dropped my chain last weekend at Coyote Point. Okay no problem just needs to be tighter. Raced it this Saturday at Surf City and dropped it a whole bunch of times then dropped out of the race (this was after checking the tension with a mech before). Two mechanics looked at my bike after and said they only things they can think of are alignment and my shitty acs freewheel.
I took it to a bike shop in Watsonville, paid 12 bucks to have a spacer put in between the hub and freewheel. Took the bike out and hammered up and down everything I could find unable to drop it. Went to race the next day and warmed up super hard making sure it wouldn't drop. Then on a super bumpy part at the end of the first lap of the race, it came off again! I put it back on and kept going for 4 more laps but then got a wood staple in my rear tire and flatter out.
Things I am going to try:
PC-890 Chain - 3/32 width and 8 speed so won't flex as much and will sit tighter on chain ring and cog. This is opposed to my current 1/8 Sram PC-1.
White Ind Trials 18t Freewheel - A new freewheel will hopefully just be better quality all around. More consistent tension with less tight spots than ACS.
Check chain alignment with calipers to make absolutely certain.
With those three things I cannot imagine there is anything else I could do. Would the rear hub for some reason have an effect? I am going to be building up a new tubular rear wheel soon and am wondering if I should go with a phil hub instead of white to see if for some reason that has an effect. Can't go Chris King because I have 120mm dropouts.
Are you running a tensioner? I can't figure out how it'd jump off if you had horizontal dropouts and full tension on it, I can't even get mine off unless I loosen up the wheel. I've had my SingleCross for two seasons, I train on it weekly and have never dropped the chain.
Oh yeah I should have mentioned I previously had the wheel on a Specialized Tricross Singlecross with a surly chain tensioner and now I have it on a Rock Lobster with sliders. These tensioners are bolted down and not coming loose. The wheel is a White Industries Standard Eno Hub (not eccentric) laced up at to a DT Swiss Rim with a new ACS 19t freewheel (happened with an older ACS 18t as well).
I did not have this problem with the original Specialized wheel on the Tricross.
Again I am hoping a new chain, new freewheel, and making absolutely sure the alignment is correct will fix this.
If you have full tension on the rear wheel, and you're still dropping the chain you should see if your chainring is bent. With that much tension on the drivetrain, even a tiny bend in 1 or 2 of the teeth up front will knock the chain off. I have an older Peugot SS (it's my commuter, I don't race on it), and I had a similar problem. Full tension, straight chainline and still dropping the chain. Turned out I had a bent a few teeth up front. It's really hard to notice a small bend in a chainring, but take it off the bike, lay it flat on a table and you'll be able to tell that way. Unless your table is uneven...:)
As an aside, ACS freewheels are absolute garbage. http://www.k-124.co.uk Makes awesome freewheels, but they are pretty pricey.
Yeah. So it turned out to be the spacing on the rear hub. For some reason the free side of the white industries hub is super far inward. I am not sure why they did this. I have a white BB as well and it doesn't line up at all. I put a pretty big spacer behind my freewheel to try and even it out but its still not completely straight. I don't want to put a bigger spacer on in fear of loosing to many threads.
Since I a put white ind freewheel and 3/32 chain on t I have been unable to drop it. Well see what happens at SSCXWC.
It's a white crank that has the chain ring attached to the crank arm. Don't think it's possible to move those around. Options seem to be new hub (thinking about getting a phil for my tubular set) or adjustable bottom bracket.
Despite how many times I may drop my chain, I refuse to use a chain guide on a single speed.