Snapped Rear QR Skewer when riding !

Hi

I've just bought a cheap beater for my commute and want to run it single speed . It has a 7 speed thread on freewheel (not freehub) To keep it cheap without buying a bmx sprocket and re-spacing & re-dishing the wheel, I figured I would use one cog of the existing 7 speed freewheel and one chainring up front, as I see this set up on a few other bikes around town.

So I stripped the gears at work. Whilst on my maiden voyage home last night I heard some strange noises coming from the drive train . I figured it was just the chainline (which didn't look too bad) but I suddenly lurched forward and almost crashed. Turned out the QR skewer had snapped off right where it protrudes for the drive side dropout and the wheel almost fell out. Luckily I was on a canal path away from any traffic.

It appears the chain had jumped up a sprocket on the freewheel , (though this my have just happened afterwards once wheel moved) . I'm wondering if the cause of the skewer snapping could have been the chain wanting to move up a sprocket to correct the chainline, which in turn put pressure on the skewer as the chain was effectively shortened. Does this sound likely? Like I said I cant be sure if the chain jumped up a sprocket before or after the event once the chain was slack.

I know the advice will probably be to get a proper set up, but I really want to keep it cheap as ill be leaving the bike overnight at the station, In theory it should work right?

Nothing wrong with the set-up: just done the same to turn a friend's Halford's POS into a usable "lock-up and leave" bike.

The QR almost certainly snapped because it had been over-tightened over a period of time: it shouldn't require the amount of force you see most people using, to open and close.

Flip the lever shut and use the nut to take up the slack, then open the lever and give the nut another quarter/half turn. Don't forget to give the spindle a wipe of oil or grease: it's damp and shitty inside the axle.

Any enclosed cam QR will do: whatever your LBS has from Shimano.

If you find the wheel slipping, rather than over tightening the QR, try roughening the dropout.

Thanks Scilly, the bike looks to be at least mid 70's , although the wheels are alloy replacements I suspect the QRs are also at least 20 years old. I've bought a new front and back QR to be sure.

I just wanted to make sure it wasn't the chain jumping up the freewheel, I don't want it to happen again! I'll properly calculate the chainline this time and use some spacers on the chainring to be as close as possible.

I might try roughening the dropouts as well, they are the stamped smooth variety.

Still having issues with this - rode today with a new skewer and adjusted the chainline at the front , its pretty spot on but the chain still jumped up a cog on the freewheel as soon as I stood and put pressure on the pedals.

Im using a 9 speed chain as it was in my parts bin, could this be an issue on the 7 speed freewheel? It seems to mesh with the teeth ok, if a bit noisy.

thanks

It's the external width of 3/32" chains that varies according to the number of gears, so it shouldn't be a problem.

Jumping or skipping chains normally indicate excessive wear, so I would check for that.

its an old chain I had lying around so maybe I should just buy a cheap 7/8 speed and try it out! Cheers.