Single speed conversion

Sea_Green_Incorruptible

Re-posted from Road Gear section...

OK folks. All this talk of single-speeds and fixies has got me interested. So interested in fact that I’m toying with the idea of converting my old roadie (Raleigh Ultimate with very tired Tiagra groupset, drops and totally knackered STI levers. Sound frame and carbon forks. Wheels OK-ish. 7000+ miles ‘on the clock’) to a flat-bar fixie if possible, single-speed if this proves to be too tricky.

Various websites around telling me what to do and it all seems straightforward-ish. The main difficulty seems to be to do with maintaining the chain tension on a multi-gear conversion with vertical dropouts.

So… a couple of specific questions for those in the know:

1) First, the dropouts on the bike are replaceable. Anyone know if there’s such a thing as replaceable horizontal dropouts I can get instead to get round the chain tension problem? Not sure how specific they would have to be to fit my frame mind.

2) As I said, the current groupset’s ‘tired’ and the wheels are only OK. Which means I wouldn’t be averse to changing the lot if necessary rather than trying to clean them all up and convert them. Is there anyone out there who manufactures this kind of conversion kit: e.g. new wheel with fixed hub + single speed crankset + chain? Where would I buy such a thing? And any idea of what sort of price I could expect to pay?

3) And would replacing the whole drive train help with the chain tension issue (i.e. the chain would be designed to fit) or would I still be left with ‘issues’ here? Any easy fixes that anyone knows of?

Anyway. Sorry for all the questions. I’m digging around on t’web myself but any help/advice/wisdom from existing single-speeders would be greatly appreciated. I’m really getting excited by the idea at the moment. Cool project for my Xmas leave!

velocitizen

You could use a chain tensioner or leave the rear mech on to tension the chain, just select the gearing you want and then adjust the limits on the mech.
If the groupset is tired rather than worn out then just put a new chain on. remove your front mech. and shifters and put them on ebay.
The other advantage of this is you can play about with gear ratios to see what suits your riding.
When you've decided there are spacer kits for running single speeds instead of a cassette, Leisure lakes do one.
Just go out and ride in one gear for a day and take it from there.

peejay78

1. if it's a steel frame you can get new dropouts welded on for not too much dosh, even with trackends. it's a bit drastic, and you can get an old 531 or 501 raleigh with hoz drops for less on ebay.

2. chain tensioner is a possibility, but it looks vile and there'll be no riding fixed for you my friend.

3, cranksets can be picked up fairly cheap, sugino, miche, ambrosio all fairly good price. rpm is dirt cheap and a bit nasty but perfectly functional. buy a 1/8 chain from anywhere, you can run a 1/8 with a 3/32 on the front if you want to keep existing chainring/crank. rear wheel, built, with sprocket, expect to pay £90-100.

4. half-link or chain tensioner is one option. the other is an ENO white industries eccentric hub, it has a funny axle thingy that allows you to tension because it is offset. http://www.sheldonbrown.com/harris/white-hubs.html

Sea_Green_Incorruptible

Brilliant. Thanks very much. I'll let you know how I get on...

Sea_Green_Incorruptible

Here we go folks - here's the final result.

I ended up abandoning the fixie idea as it was just too tricky. Otherwise, it all turned out to be remarkably straightforward (and cheap too).

Stripped the whole bike down and cleaned everything up. Removed the front and rear derailliers, the big chainring from the crankset (replaced with a washer on each fixing bolt), the drop handlebars, knackered STI levers and gear cables. Took the flat handlebar and brake levers off my old (knackered) mountain bike. Then bought some new brake cables, shortened the chain and put it all back together. Got lucky on the chain tension too - probably a wee bit too tight but not by much. The one thing I've got left to do is replace the unused sprockets at the back with spacers.

Otherwise I am well pleased. The ride is fantastic: so smooth and silent! Just the thing for popping down to the shops. Thanks to all those who gave me advice!

peejay78

are you running it fixed or ss?

Sea_Green_Incorruptible

Ss. Fixed proved to be just too much of a pain.

I think the chain is too tight though. Will need to get a chain tensioner....

peejay78

it might be, it looks a little tight for SS.

you might not need a chain tensioner, you could try a half-link, or it might even wear in a bit and stretch.

wildwildebeest

does the chain tension need to be higher for fixed than ss??

meagain

"does the chain tension need to be higher for fixed than ss??"

Ideally the same. However can usually get away with slacker on single free than with fixed - and if do drop the chain on free an inconvenience rather than the potential disaster with a fixed!

Yours does look on the "bar-tight" side to me!

wildwildebeest

That's not my bike above - I've just rudely interrupted....
I'm gonna build up a bike with a filp-flop hub though and just wanted to make sure that I could successfully flip it over, considering I have vertical dropouts and so very little room for leeway in terms of tension.
I take it that disaster you mentioned is just the lack of brakes if the chain comes off.
Thanks for your reply - please shout if it sounds like I'm screwed for some reason

meagain

"I take it that disaster you mentioned is just the lack of brakes if the chain comes off."

More likely a sudden severe lock-up of the whole transmission than lack of braking! Demolished rear wheel. Worst case, chain stays part company...

And I know that CAN drop a chain on a fixed without real trouble (I've done it) but at speed best avoided.

FWIW I really think that running fixed in verts is more trouble than any saving it's worth (other than with an Eno eccentric hub - and that only if got a favourite frame to hand for next to nowt).

Have a read of the Fixed:FAQs (link given recently, I think).

wildwildebeest

gawd that does sound pretty bad!
Don't see how its quite so dangerous though - surely if the chain gets jammed then the wheels and the pedals lock up and you just skid to a halt?
didn't really understand your "And I know that CAN drop a chain..." sentence....

meagain

Sorry, simply meant that it can happen with only minor consequences, but that I wouldn't like to rely on such luck!

redvee

If the chain tension is a little tight then your more likely to kill the BB, a friend got lucky with his chain tesion and killed his BB within a month cause it was a little overtight.

wildwildebeest

ok thanks - what's the best way of judging when the tension is just right? (sounds like common sense won't be exact enough)

meagain

Half an inch up and down mid way along the chain run is my guide.

Rare for tension to be exactly equal ALL way round a complete revolution, so at tightest point.

Lots of tips re equalising tension etc etc on Fixed FAQs as I recall. Well worth a read!

wildwildebeest

Sorry! I did read it - honestly, just not too thoroughly
Thanks for all the help

krakow

I'm thinking of doing this to my current everyday bike, a Dawes Discovery 501 which I have been riding into the ground for the last 8 or so years.

Once again the drivetrain has reached a serious state of disrepair and this time I'm not particularly keen to get it all replaced yet again due to the cost. I've ended up using increasingly fewer and fewer of the gears over the years and am pretty sure that I could survive with one, especially taking into account the weight and maintenance benefits.

I'm wanting to canvas opinions on the various singlespeed conversion kits available.

It's got vertical dropouts and runs a very basic shimano 8-speed freewheel cassette as far as I know, so a chain tensioner and spacer/cog kit is what I have in mind. Of the various kits available, are there any particular recommendations or ones to be avoided? The readily available options seem to be:

On-One singlespeed conversion kit and their couple of doofers
DMR singlespeed conversion kit or their more expensive tension seeker2 and separate spacer kit
Charlie The Bikemongers singlespeed conversion kit, which I think uses Gusset stuff
Surly Singleator and a spacer/cog kit

Is there anything to choose between these, or are they much of a muchness? Other suggestions welcome of course.

Thanks

natmat

I've used a DMR tensioner, with orange roller wheel, that attaches to the derailleur hanger.

Had endless problems of this seizing up in the winter. Was oiling it weekly, but over the course of a weekend without riding it frequenlty rusted up solid. Though they claim sealed bearings, they're not the best.

When new it worked a dream, but 1000 miles/2 months later it was in need of constant fiddling.

IMHO A basic spring tensioner (aka fixed rear mech) with jockey wheels is the best compromise for vert dropouts.

krakow

Ah well, DMR kit now fitted and up and running, following various suggestion in the 'Know How' version of this thread, which garnered a bit more action. We'll have to see how it goes in the long term.

NorwegianBlue

natmat wrote:

I've used a DMR tensioner, with orange roller wheel, that attaches to the derailleur hanger.

Had endless problems of this seizing up in the winter. Was oiling it weekly, but over the course of a weekend without riding it frequenlty rusted up solid. Though they claim sealed bearings, they're not the best.

When new it worked a dream, but 1000 miles/2 months later it was in need of constant fiddling.

IMHO A basic spring tensioner (aka fixed rear mech) with jockey wheels is the best compromise for vert dropouts.

The one with orange roller (rather than a jockey wheel) is intended for street/dirt jump use, not for riding any distance. DMR are quite clear on the point.

I've tried DMR (Mk1 and Mk2) and Surly sprung tensioners and frankly they were all rubbish. They may clean lines when viewed from the side, but when you look at the design they are never going to work very well. Actually the DMR STS that you mention is a pretty nice design, except for the roller wheel. If a similar thing exists with a proper jockey wheel and an ajustable chain line then that might do the job batter. Otherwise stick with a short cage rear mech. If you're image conscious about your single speeding then it's not so good, since the casual observer may assume you are running gears. However if you are image conscious about your single speeding then you're not a real cysclist anyway, you're a fashion victim. <SHIELDS=UP>

If you have to stick with vertical dropouts then the only way to do the job properly is to use a White Idustries exentric hub. Not cheap at about £80 the last time I looked, but a sound bit of engineering that does the job almost as well as running track ends or horizontal dropouts. The right frame is of course the best solution, unless you can find a suitable frame at a bargain price then it can be costly.

The other way to do it is to try different combinations of front and rear tooth counts, and throw in a half link if necessary to get the tension approximately right. Some call it the magic ratio. Yes wear does mean that when your tension goes out with chain wear you either need a new magic ratio or new chain.

krakow

Thanks for instilling such confidence in me. ;-)

I ride about 100-150 miles a week, most of them on that bike, so it won't take long before any failings show up.

I've persevered with the bike, because I still feel a loyalty to it after all these years of it getting me pretty much everywhere, despite how badly I've treated it. It still seems a solid bike and I couldn't bear to give it up, hence this attempt to breath new life into it.