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I recently knocked up a single speed for messing in the street/BMX track and taking the kids to school.
Its a vertical dropout frame set up using a N/W front ring, a spare 15 tooth rear cog from an XT cassette, and chain tensioning is courtesy of a black spire stinger.
At first I didn't have the rear cog spaced correctly so I dropped the chain a few times off the front, so I realigned the rear, but now I keep dropping the chain off the back. I'm pretty sure it's all straight, but could it be because i'm using a cog that is supposed to be on a cassette for a geared bike? would the ramped teeth be causing it to drop off every now and then? Or could it be a tension thing???
It's my first foray into single speed since BMX's as a kid!!
Tension, surely? IME stingers aren't great, but then I might have not set it up too well.
The XT cog would be my guess. Cassette cogs are designed to shift up and down - only a few quid to get a proper SS specific one which I'd have thought would fix it.
Rob, yeah It's a BB mounted one as well but doesn't seem to be moving. I might add some more tension and see....
DBW that's what I'm hoping. Will get one ordered.
I'd guess a combination of the two.
My ss proper has a habit of losing the chain if a bit loose (and it doesn't need be much, just a few mm on the drop outs and some bouncy terrain).
With a shift cog anything other than bow tight will catch and drop every so often I'd expect.
I'll tighten the stinger up and see how it goes.
I didn't want to put too much tension on it as the first ride I had on it, it flipped my over the bars in the middle of the road when a chain ring bolt popped when i was putting the power down about to jump up the kerb!!
Fortunately their was no traffic around at the time and it was probably to do with the duff chain ring bolt (or my cack handedness) rather than anything else, but i'm a bit paranoid about adding too much tension now..... 🙄
I ran a Stinger on a SS for years with no droppage. Proper Shimano SS sprocket.
It's the cog on the back. I've used a Stinger thinger on SS for ages as well, including on a couple of DHs, and I've never had the chain come off. Cassette cogs have lower profile teeth than SS cogs [i]and[/i] they're designed to derail/work with a squiffy chainline- SS cogs have taller teeth and are designed to run with a straight chainline.
Right new cog ordering time then.
Cheers all.