Single speed conversion hiccup

david 142

I'm posting here in the hope that some readers will have travelled further down the road I've started...

I've just dismantled a cassette to procure a selection ofsprockets and spacers which I plan to use to try single speed with a freehub wheel. I knew why I was doing it - simplest way to control chain line etc. - but I've just re-realised that the lock ring engages with teeth on the smallest sprocket.
Do I need to install this sprocket as the outermost spacer (in which case it might be a good idea to grind off the teeth) or will it be safe to simply tighten the ring down against the stack of assorted of spacers (and one sprocket!) that I end up using?

s.frisby

I understand, but I'm sure that other people will tell you more, that a firm - I think it might be surley - make and will sell you a conversion kit that will solve your problems. :shock:

ColinJ

david 142 wrote:

I've just dismantled a cassette to procure a selection of sprockets and spacers which I plan to use to try single speed with a freehub wheel. I knew why I was doing it - simplest way to control chain line etc. - but I've just re-realised that the lock ring engages with teeth on the smallest sprocket.
Do I need to install this sprocket as the outermost spacer (in which case it might be a good idea to grind off the teeth) or will it be safe to simply tighten the ring down against the stack of assorted of spacers (and one sprocket!) that I end up using?

Hi David.

My mate built up a single speed bike for me to ride on my frequent trips back to Coventry. I've done about 100 miles on the bike so far and it has been great for the undulating lanes between Coventry, Birmingham and Nuneaton.

To answer your question - we just tightened the lock ring against the spacers and it seems to be fine.

More info that might be useful...

I preferred the look of the chainring on the outside, so I moved the 39 ring to where the 53 used to be and discarded that. I was able to tighten up the bolts to take up the slack, but it might be necessary to buy some shorter threaded studs (don't know the technical name for them!).

We started off with two cassettes so we had plenty of spacers. For the first attempt, we just used spacers and a 15 tooth sprocket placed in the right position to get a perfect chainline. When I went for a test ride, I quickly managed to drop the chain off the sprocket despite having no slack in the chain and an ideal chainline. I put it back on, then it happened again. I had a think about it and concluded that a sprocket from a cassette is actually designed to permit the chain to move easily off it, otherwise a derailleur wouldn't work! I came up with a solution to this problem - I replaced the spacers two away from the 15-tooth sprocket on either side with 17-tooth sprockets (I had two cassettes, remember, but the idea should work equally well, say, with a 17 and a 19). These extra sprockets act as chain-retention guides and since fitting them, I've had no further problems with dropping the chain.

I wouldn't get away with a s/s bike back home in Yorkshire but it is fun to ride something different down here in flatter terrain. The transmission feels smooth and efficient, and the bike is very quiet. Hills are hard work on 39/15 though!

PS I used Campag hub/cassettes.

david 142

Thanks chaps! I just needed some reassurance that the lockring wouldnt jump off as soon as I took my eyes off it!

I have seen the conversion kits - IIRC they were selling for about £20, which seemed like a lot to spend just to try out an idea. If it works out for me, well thats something else - bring on the bling then, by all means!

Thanks for the warning about the chain dropping off. I expect theres some truth in your explanation for this, but after mulling it over I'm a little puzzled. You comment on how smooth and silent your transmission now is - as it should be, of course! Well if the chain is regularly being nudged back into place by a "retainer" wouldnt that make some noise?

I expect I'll know the answer to that in a few days so dont rush to tell me. I'm targeting the sprockets from the middle of my cassete, so I too will have a couple of bigger ones to play with - another good waste saving idea!

ColinJ

david 142 wrote:

Thanks for the warning about the chain dropping off. I expect theres some truth in your explanation for this, but after mulling it over I'm a little puzzled. You comment on how smooth and silent your transmission now is - as it should be, of course! Well if the chain is regularly being nudged back into place by a "retainer" wouldnt that make some noise?

The sound of gentle nudging compared to the sound of a longer chain being pulled round two jockey wheels seems to be negligible!

I was surprised how much weight is saved by having such a simple bike. I reckon it weighs about 19-20 pounds and that is with a steel frame and forks.

There are some pictures of the bike in this thread. I've changed the pedals to SPDs since then and the pictures were taken before I sorted out the chain problem.

PS It has just struck me - if you only have one cassette, where are you getting the extra spacers from? I used extra spacers from the second cassette to replace the 6 sprockets I removed from the first one.

peejay78

what gearing are you running colin?

just interested how you manage to get out of hebden on a fixed wheel. or is it ss?

ColinJ

peejay78 wrote:

what gearing are you running colin?

just interested how you manage to get out of hebden on a fixed wheel. or is it ss?

I got out of Hebden Bridge by riding down the valley road to the railway station and bringing the bike to Coventry on the train ! I left it here so I don't have to mess about carting it back and forth every visit.

It's not a fixed wheel - it is a s/s I put together from scrounged bits and pieces. I had to spend only £25 on cables and a new seatpost to get the bike on the road. I wanted a decent inexpensive bike to ride in the midlands because I've been spending about 10% of my time down here since my father died. I really missed having a bike handy on nice sunny days.

The s/s is fine on North Warwickshire lanes though I have found a few little 10+% hills which needed some grunt to get up on the 39/15 gear.

If I was riding the bike in Yorkshire I'm afraid I'd stick to the valley roads! I normally ride either 52/39/30 + 14-28 or 53/39 + 13-29 on those hills...

david 142

Nice looking bike! If the current low budget version works out in practice, ie. gets ridden lots I'll be looking for some quality components too.
I was impressed by the weight savings myself, and after this afternoons towpath excursion with t'son and heir I'm also impressed with how much easier it'll be to clean

Extra spacers? Nice man in LBS offered me some when I explained what I was up to. Some of them were 10sp too - very useful for fine adjustments!

ColinJ

david 142 wrote:

Extra spacers? Nice man in LBS offered me some when I explained what I was up to. Some of them were 10sp too - very useful for fine adjustments!

You could well be right. I took a very close look at my chainline last night and I reckon that it is actually about half a spacer off perfect. That could explain why I had that chain-dropping problem but I find it reassuring the way the bike is set up now with extra sprockets as chain guides so I won't mess about with it. I had my worst ever cycling accident as a teenager when my chain slipped. I was sprinting out of the saddle at the time and I went over the bars, headbutted the road***, banged my knee, then used the top of my left shoulder as a brake :shock: :shock: :shock: - I don't fancy that happening again...

*** No, I wasn't wearing a helmet at the time but if I could have paused in mid-flight I'd definitely have done that and put one on! I ended up with a lump the size of a hen's egg on the top of my head.