Just doing up an old Cannondale M400 as a ‘riding with the kids’ bike and thinking of going singlespeed.
Is the DMR kit the easiest way to go?
I’ve got some decent cogs from the old cassette so thinking I just need a spacer kit and chain tensioner..?

I used a kit very similar to the DMR one and it does the job well. . Standard cogs from a cassette might wear quickly so worth going for a 1/8th cog and chain.

I wouldn’t go 1/8″, 3/32″ geared chains will work better, but I would definitely recommend using a dedicated singlespeed (and 3/32″) sprocket. You can pick up singlespeed kits with 16/18T sprockets easily and cheaply.

Surley singlespeed cogs are excellent. I use a 15 and 17 with a tensioner and spacers and you can have two singlespeeds for the price of one! I have reverse dropouts, and they accommodate this change, the DMR will make it even easier. Completely agree about 3/32″, your existing sprockets will work, but the Surleys are in a different class.

I’d also go 3/32 as I found stuff more readily available.

FWIW you can get cheaper tensioners than the DMR. I preferred the ones with jockey wheels rather than rollers because they were quieter. If you can find them then push up is better than push down to get better chain wrap.

Get a dedicated sproket at the back – you risk slippage with an old cassette.

I’d recommend having a look at Charliethebikemonger

http://www.charliethebikemonger.com/one-speed-kits-216-c.asp

or you could try velosolo.

I use the Singleator from Surley as a tensioner, can be run to pull up or down. For sprockets, the On-One Groove Armada is my current favourite. I run a narrow wide front chainring, purely because I had it spare, really, on the front anything will do.

Gearing on a 26″ wheel, start at 1:2 for road/offroad mix, will get you up most things and gives you enough to not spin out instantly. I use a 36 front 18 rear because more teeth = less wear!

https://www.planetx.co.uk/i/q/SKOOSSGA/on-one-groove-armada-single-speed-sprocket

http://surlybikes.com/parts/drivetrain/singleator

Steve, I got a box of SS bits if you want to come and rummage. Couple of tensioners, 16t and 18t sprockets, short on spacers though.

Stoner, thanks. I’ll PM you 🙂