Singlespeed Help

buddy_club

Right, I want to convert the retro road bike (in sig) to a singlespeed. It has 5 gears at the back and 2 at the front. Would i be able to replace the screw on 5 speed block with one of these: http://www.ebay.co.uk/itm/270933565644?var=570107480115

The chain with one of these:
http://www.ebay.co.uk/itm/231096929072?var=530445791596

And then leave the inner chainring (its a 48t or 47t iirc) and just remove the outer as i imagine finding a new chainring to fit such an old crankset would be a big PITA?

Also what size would you recomend the cog be at the back? With a 48t up front and a 17t at back the gear inches would be about 75 (according to sheldon browns gear inch calculator) - does this sound reasonable for someone not particularly fit but in a reasonably flat area?

craker

I don't think that freewheel will work - _if_ it does screw on and the hub has a bearing race on ... your chainline will be so far out it will give you problems.

I'd suggest getting a wheel with a 7 speed freehub, failing that get a 9 speed freehub wheel and stretch the rear triangle (I did this on my old Raleigh & it may have been responsible for its recent demise... cracked weld on the chainstay.

Gearing wise, my old bike was 74" (39 x 14) which was great on my hilly commute - tough on the big climb to be sure but enough gearing to keep pedalling up to 27 mph +). My new bike - arrived Thursday - is a Specialized Langster. I've only ridden it home so far, it's on 75" (48 x 17) fixed. Felt a whole lot harder but it was a rotten windy wet day. Give 75" a go by all means but you my find it hard going to start with.

JayKosta

I think the 'single speed freewheel' is intended for use on a true 'single speed hub' in order to convert from FIXED to rear cog that can freewheel.

You could just remove the front and rear derailleurs and adjust the chain length to fit whatever front / rear gears you want. And yes, it would look goofy...

Jay Kosta
Endwell NY USA

buddy_club

Thanks for your input, i did wonder about the chainline - but read on sheldon brown that the chainline would only work on the granny ring - the 48t i plan to use. Could you point me in the direction of a cog or spacer kit i could use to convert? Im not really sure what i'm looking for. Also if possible i'd like to keep the current wheelset - as trying to convert as cheaply as possible.

JayKosta - im looking to go full singlespeed rather than just removing derailleurs - i'd rather keep the gears than just run SS on the current 5 speed block.

buddy_club

So having measured the the distance between the inside face of each rear dropout it appears the frame spacing is about 125mm, yet it seems this is not a common size - it could be 126mm but according to sheldon brown that spacing was used only for 6/7 speed bikes? So it would appear that the frame is designed for 120mm rear wheel but has slightly widened (perhaps due to its age?)

So will i be able to reuse the chain on an existing ring?

Will the chainline be reasonable with a screw on singlespeed cog and the chainring mounted on the inside of the cranks in the granny ring position?

cycleclinic

125mm or 126mm it the same practically. Your frame has not been spread. You can try your idea of the granny ring postion to correct chainline but you will be limited on the size of the chainring you can fit.

id buy a cheap 8 speed rear wheel and use a conventional single speed kit. I think trying to use your existing wheel will end up with comprimises which may or may not cause you a problem.

buddy_club

thecycleclinic wrote:

125mm or 126mm it the same practically. Your frame has not been spread. You can try your idea of the granny ring postion to correct chainline but you will be limited on the size of the chainring you can fit.

id buy a cheap 8 speed rear wheel and use a conventional single speed kit. I think trying to use your existing wheel will end up with comprimises which may or may not cause you a problem.

Thanks, looked at a few cheep wheels, all of 1hich are 130mm? It'll be alright to use a 130mm wont it? Also what chain will i need and will i be able to reuse the existing chainring?

cycleclinic

You can reuse the chainring if its not worn. You will need to spread the stays to fit a 130mm spaced wheel. Look harder 126mm spaced wheels are out there.

craker

You can reuse your chainring, get a 1/8" wide single speed chain and a single speed conversion kit (spacers and cog) with the appropriate gear.

The more bits of my old transmission of my 2 x 7 geared Raleigh I reused the worse the reliability was - in particular chains for multispeed bikes are designed to be flexible and gears have ramps on to help the chain on and off. So my chain fell off quite alot to start with.

The other thing I had trouble with was the quick release on the rear wheel - I had problems with the wheel shifting forward in the dropout. It's not a massive problem, tighten your lever up good and hard (and it worked better when the lever was on the drive side).

buddy_club

craker wrote:

You can reuse your chainring, get a 1/8" wide single speed chain and a single speed conversion kit (spacers and cog) with the appropriate gear.

The more bits of my old transmission of my 2 x 7 geared Raleigh I reused the worse the reliability was - in particular chains for multispeed bikes are designed to be flexible and gears have ramps on to help the chain on and off. So my chain fell off quite alot to start with.

The other thing I had trouble with was the quick release on the rear wheel - I had problems with the wheel shifting forward in the dropout. It's not a massive problem, tighten your lever up good and hard (and it worked better when the lever was on the drive side).

Did you use a screw on singlespeed cog for your Raleigh?

craker

No I guess my old Mavics were the right era for the conversion - splined seven speed freehub, simple conversion. When they died I got a nine speed set and bought a seven speed freehub for it off the 'bay (I may still have it somewhere) which worked a treat and meant I didn't have to spread the frame. For the follow up wheelset I stretched the frame. Now it's broken.