Semi-single speed conversion?

[StrontiumCat]

Have an old Raleigh that I'm considering converting to single speed. However, also wondering if I can just drop to one cog on the crankshaft and keep the original 6-speed cassette on the back? All seems straightforward enough, but are there any pitfalls I need to be aware of?

 

[Sharky]

No, it's good idea to keep the 6 speed block, so you can experiment with different cog combinations.

Just need a method to tension the chain and if you have horizontal rear drop outs, that will be fine.

If you are planning to remove one of your chain rings and leave it as a single, then you might have to get a new set of chain ringbolts or use spacer washers.

Is the rear a cassette or a screw type block? If the latter a single speed freewheel will screw on.

Good luck
Keith

 

[raleighnut]

Yep, easy to do and it'll drop a fair bit of weight. The difficult thing will be deciding how many teeth to have on the front but that will depend on the terrain you plan on riding it on.

 

[raleighnut]

I got the feeling he was talking about a 1x6 conversion.

 

[TheDoctor]

1 x 6 is perfectly doable. If you're planning on actually singlespeeding it, then yes, you can use just one of the sprockets on the freewheel, but you do need a reasonably straight chainline. At a rough guess, the single chainring will probably line up with about the 4th or 5th sprocket if it's mounted on the outside, and the 2nd or 3rd if it's on the inside. Crunch the numbers to see which one gives you the right sort of gear. FWIW, I'm running 39X17 on the singlespeed ( I think!) for a 62" gear, which suits me. The fixed is 39X15 for a 70" gear. Either way, I'd mount your current inner chainring (39T or 42T, perhaps?) on the outside of the spider to line up with the 5th sprocket - probably a 16 or so. Mounting the current outer chainring on the inside of the spider and using the 2nd sprocket would probably give you a workable gear too. Like I said, start counting teeth and crunching numbers

 

[Threevok]

The only thing I can see you having a problem with is the chain jumping off - this of course will only be a problem if you are intending to take it off road.

On road should be OK, if you get the chainline correct as @TheDoctor has said

 

[raleighnut]

1 x 6 is perfectly doable. If you're planning on actually singlespeeding it, then yes, you can use just one of the sprockets on the freewheel, but you do need a reasonably straight chainline. At a rough guess, the single chainring will probably line up with about the 4th or 5th sprocket if it's mounted on the outside, and the 2nd or 3rd if it's on the inside. Crunch the numbers to see which one gives you the right sort of gear. FWIW, I'm running 39X17 on the singlespeed ( I think!) for a 62" gear, which suits me. The fixed is 39X15 for a 70" gear. Either way, I'd mount your current inner chainring (39T or 42T, perhaps?) on the outside of the spider to line up with the 5th sprocket - probably a 16 or so. Mounting the current outer chainring on the inside of the spider and using the 2nd sprocket would probably give you a workable gear too. Like I said, start counting teeth and crunching numbers

If it is the standard basic Shimano crankset that Raleigh used then the chainrings are riveted together (and are steel so virtually indestructible) but a square taper single ring crankset is quite cheap.

 

[ColinJ]

I got the feeling he was talking about a 1x6 conversion.

I thought so too!

But as for single-speed conversions ... I did one last year and up to now have done about 800 miles of the bike. I chose a 52/19 gear which is about 72". That works well for undulating roads and moderate hills. Anything steeper than ~9% is too hard, as are long stretches of 6+%. It is a good gear for 12-24 mph which is 99% of my time away from big hills.

I fitted a Planet X 'Doofer' chain tensioner. It didn't work very well the way that it is designed to work which is to pull the lower run of the chain down. It reduced the number of teeth that the chain was engaging on the sprocket from an old cassette. As a result, the chain peeled off the sprocket several times in the first few rides.

I took the Doofer to bits and rearranged the spring to get the tensioner to lift the chain instead and wrap it round more teeth on the sprocket. That proved pretty reliable.

I was starting to get irritated by the sound of the Doofer bouncing up and down on bumpy roads and then I dropped the chain after one big hit. I decided to take the spring out altogether and set the tensioner position by hand and lock it there. In order to do that I had to fit a couple of thick washers to stop the mounting bolt running out of thread. The bike is much quieter now and the chain runs more smoothly. I will have to manually adjust the tensioner as the chain wears, but that is no big deal - I can do it in seconds without tools.

I think this is an ideal setup for experimenting with single-speed. Perhaps choose something like 52/21 (65") for slower, lumpier rides, or 52/17 (81") for faster, flatter rides?

 

[StrontiumCat]

Thanks guys, that's some great stuff to be getting on with. I'm fortunate enough to be near a brilliant LBS - shout-out to http://www.williams-cycles.co.uk so I'll have a chat with them and cost it out. What do you all reckon parts will set me back, roughly?

 

[ColinJ]

What do you all reckon parts will set me back, roughly?

I used a sprocket from an old cassette and spacers from 2 old cassettes so they didn't cost me anything. The 'doofer' cost about £15.

You can buy a single-speed sprocket and spacer set from about £10 (example) if you don't have spare bits lying about.

 

[StrontiumCat]

What a great community you guys are. Genuinely, you're brilliant.
Pleased by the cost too. End of the day, its a big fat fashioned-from-girders bike that was entry-level back in 2001 so I'm loathe to plough too much money into it. I'd got into my head that anything worth doing to a bike would be expensive, and I'm chuffed this isn't the case.

 

[raleighnut]

I used a sprocket from an old cassette and spacers from 2 old cassettes so they didn't cost me anything. The 'doofer' cost about £15.

You can buy a single-speed sprocket and spacer set from about £10 (example) if you don't have spare bits lying about.

It's a screw on freewheel on that bike.

 

[Threevok]

In which case you should be able to get a Single speed freewheel (or even a fixie should you so fancy) to fit it (assuming you want to go single speed and not 1 x 6)

 

[midlife]

Just curious, is it all working OK at the moment?

 

[raleighnut]

Thanks guys, that's some great stuff to be getting on with. I'm fortunate enough to be near a brilliant LBS - shout-out to http://www.williams-cycles.co.uk so I'll have a chat with them and cost it out. What do you all reckon parts will set me back, roughly?

One of these should do the job very well,

https://www.spacycles.co.uk/m2b0s109p2188/STRONGLIGHT-ST55-Single-Chainset

You just need to work out by using the triple which size ring would fit your needs best.

I'd also take the advice of the majority of bike shops with a pinch of salts, they'll tell you a rigid Raleigh MTB is not worth spending money on when the truth is they're one of the best 'utilitarian' bikes going. Sure they're a bit 'hefty' but they're also pretty 'bombproof'.


EDIT - BTW if it was mine I'd fit one of these,
https://www.googleadservices.com/pa...ahUKEwimnr73xsDUAhXFOxQKHR2RDYIQvhcILg&adurl=