Using just 1 chain ring without a front deraillier

[cyberknight]

Yes, assuming you are using flat bars.



I am a bit surprised by your selection of ebay chainsets from 36T to 48T - if I were you I would use a gear calculator to try to work out what is the smallest front ring I would be happy with a 11T rear sprocket, and search for a chainset from that. This will give you a decent shot for a light, tight setup. Some sort of logic is here.

I have been advocating and running the same Stronglight 55 Doc suggested above for some time. It is a remarkably light piece of kit (strong enough for anything on the road other than a fixie imho) for peanuts - my 40T is only 465g. Coupled with a UN72/73 (alas unfortunately these things are increasingly rare in decent shape) you will have a ~700g chainset+bb combo, which for the princely sum of c£35 in total is simply astonishing (ok let me put it this way, it is impossible to achieve same currently with Shimano kit without going all the way to DuraAce...). Incidentally, I use a 115mm JIS spindle to achieve 43mm chainline with the 55, so a 118mm JIS will give you 45mm.

I was trying to do it on the cheap as cash is as always an issue and single chain rings are new to me as i have always run a double , from what i gather the bike will have a 120 mm BB and a 52/42 crankset is on offer but i just wanted the simplicity of a single ring for a winter hack
That spa cycles chainring does look like its on the money and about the right size as after a play with a gear calculator i reckon a 40 tooth front will be enough for a laden commuter as i can spin a 34 x17 close to 20 mph