Hi
Looking to convert an old Dawes Tamark mtb i have kicking around. Im just wanting it nice a simple to use as a go to shops or pub bike. Im thinking of using on those DMR Simple Tension Seeker & Single Speed Kit. https://www.chainreactioncycles.com/dmr-simple-tension-seeker-single-speed-kit/rp-prod10009
Question is would this work? also what do i need to do with the front chainring can i use whats there or do i need to remove some and change. Any advice would be much appriciated.

thanks
Tom

You can tend to get away with mix and match on a singlespeed as, well, there’s only one gear to set up. I’ve just done a BFe 26 commuter conversion with a Surly singlespeed kit (13t), Deore 30t chainset with a narrow wide chainring, SRAM PC-1 chain and a chain tensioner. Mix of speeds in there but all works flawlessly, just make sure you check chainline and tension.

Yes, that would work. I’d contemplate getting a better cog with a wider base if you have an aluminium freehub to stop it digging in, but that kit would work.

eg: https://www.bikemonger.co.uk/halo-fat-foot-18-single-speed-cogs-1419-p.asp

Actually I can look in my spares box and see if I have one.

For the front chainring, a normal front ring will work but may be prone to dropping – usually when giving it beans out of the saddle. What do you have already? For a road / pub bike the usual 32:16 or 32:17ish might be a bit light, depending on where you live. A tall tooth, or even a N/W might be better, of a size to suit the ratio

I use one of those cheap tensioners on my work/shit bike. It works fine but be aware that the arm can only take up limited slack. Consequently, many chainring and cog combinations won’t work. It took me a few attempts to fit a useable combo.

what combination did you find worked the best just outta interest?

I think it’s 38 x 18, but YMMV.

Any variation on 2:1 gearing (32-16 etc) will work reasonably well on a 26″ wheeled bike for just riding arround unless you have a particularly steep hill to get over. Off-road a bit lower works much beter than a bit higher as pedaling downhill is of limited value even with gears

Tensioners tend to work fine untill you try to run any sort of new chain + worn chanring/sprocket combination when they’ll skip just like a geared bike, whereas an actual SS frame really will let you run components untill the sprockets are almost a circle as there isn’t enough slack to skip. Keep the same chain though and it’ll last for years with no issues.

Decent explanation on gear ratios.

https://surlybikes.com/info_hole/spew/spew_single-speed_gearing_101

Even if you find the perfect ratio for your current riding, you’ll probably want to tweak it a touch once you’re used to it. There is no right or wrong singlespeed gear, only what you prefer.

Try to buy steel singlespeed specific chainrings, chains and sprockets. They’re cheap and last ages. But using what you already have will probably do.

Messing around with singlespeed bikes is part of the fun. 👍

Also the main singlespeed chain width is 1 1/8″ and 1 1/4″

The latter is bigger and supposedly stronger but I’ve never had any issues with the former.

You may get lucky and find you don’t need a tensioner if chainstay and gearing are just so.

Half link chain is another route to removing a tensioner from the system.

Thanks guys for the advice. I’m gonna have a play about see what I’m happy with and what works well. Always fancied a single speed for bobbing around on make sense to use this bike.

Thanks
Tom

You may get lucky and find you don’t need a tensioner if chainstay and gearing are just so.

And you can use the following to work out which ring/cog combination will get you there

magic gear calc

Works okay for single speed but would not rely on it fixed as when chain wears it will be too slack for fixed gear.

For a hack bike, use whatever you have. I do lots of singlespeed off-road and have always used a normal front chainring and normal 8 and 9 speed chains (no weaker than a 1/8th).

Singlespeeds are fairly tolerant and don’t need a perfectly tensioned chain, you can easily run it with the bottom section of the chain having a bit of a droop, so I’d set it up and then consider if you can use a 3/32 half link (won’t work with narrow wide rings), or need to go the whole hog and get a tensioner.

If you do resort to a tensioner, get one that will push up as well as down, pushing up is much better for chain wrap and reduced chance of skipping.

Also the main singlespeed chain width is 1 1/8″ and 1 1/4″

Those are headset sizes 😉

Chains come in 1/8″ (3-5 speed), 3/32″ (6-8 speed), 11/128″ (9+ speed).

Those are the nominal thickness of the sprockets, the thickness of the plates and thus the spacing depends on the number of gears, so an 8speed chain will work on a 6 speed cassette (as long as it doesn’t get so narrow as to fall between the sprockets), but not vice versa.

There’re some other odd ones but you won’t see 5/32″ in many local bike shops.

Those are headset sizes

Although a 1 1/4″ wide chain would be pretty tough wouldn’t it.

I believe the dmr tensioner will push both up and down

I believe the dmr tensioner will push both up and down

It will, I wouldn’t loose sleep over it though, I’ve never managed to successfully find a ratio that works pushing up because it only gives you a fraction of an inch of movement before the tensioner hits the stay. So it’s only really workable if you have a magic ratio plus a couple of mm at most.

So I’ve always had a Surly Singulator (or the cheap on one version) pushing down on the chain and never had it skip due to that. It’s still the same/more chain wrap than a geared bike.

Just looking at them surly Singulator I guess they work the same as the dmr ones ? Just don’t include the sprockets and spacers ? Or do you just use the old bits ?

You could always use a BB mounted tensioner, which gives a really neat solution.

I’ve used the sprung, rear tensioners before, which have always worked pretty much flawlessly, but I do think the BB one is more elegant.

Where did you get your bb mounted tensioner from? What gear setup is that?

https://www.onbuy.com/gb/acor-iscg-black-chain-device~c12518~p52958696/

Running 32/19. For a while, it was the ‘magic’ ratio, but chain stretch means it needs a tensioner.

Gearing is aimed for offroad stuff, nothing too steep, but lumpy. I’d go a higher ratio for an urban/pub bike.

Just looking at them surly Singulator I guess they work the same as the dmr ones ? Just don’t include the sprockets and spacers ? Or do you just use the old bits ?

Singulators sprung so you don’t have to lock it off like the DMR. The DMR wouldn’t work on my bike as it’s a bolt through axle.

As for sprockets, I use 3/32 On-One sprockets with the wider base, the kit ones are just pressed steel so will make a mess of aluminum freehubs (fine on anything steel though). Seeing as you’ll need spacers, sprocket and tensioner anyway the kit will make more sense for you unless it’s an aluminum freehub. I’d still run 3/32 chain and a new chainring though, a slipping chain on a SS isn’t something you want to contemplate! Doesn’t need to be fancy though, cheapest 7075 narrow-wide chainring of ebay and kmc ‘narrow’ (aka 3/32) singlespeed chain from somewhere reputable as ebay is full of fakes.

p.s. you’re almost certainly overthinking it, buy the kit, fit it, realize SS is the best thing ever, then consider a more pimped setup for your main bike once you’re sold on the concept.

p.s. you’re almost certainly overthinking it, buy the kit, fit it, realize SS is the best thing ever, then consider a more pimped setup for your main bike once you’re sold on the concept.

Is is 2002 again? 🙂

Yeah your probably right. I’m gonna order one and get it put on.

Tensioners tend to work fine untill you try to run any sort of new chain + worn chanring/sprocket combination when they’ll skip just like a geared bike

That’s true only if the new-chain set-up was at the limit of the tensioner. Otherwise, just adjust the tensioner as the chain wears.

You may get lucky and find you don’t need a tensioner if chainstay and gearing are just so.

Yes if the frame has horizontal dropouts, otherwise a vertical dropout frame allows no adjustment as chain and parts wear.

Chains come in 1/8″ (3-5 speed), 3/32″ (6-8 speed), 11/128″ (9+ speed).

Those are the nominal thickness of the sprockets, the thickness of the plates and thus the spacing depends on the number of gears, so an 8speed chain will work on a 6 speed cassette (as long as it doesn’t get so narrow as to fall between the sprockets), but not vice versa.

I just whack something cheap on. I think 6-speeds are cheap 😀

can i remove the biggest and smallest chainring up front and just use the middle chainring? i guess ill just need shorter bolts to attach it to the crank?

thanks
Tom

Yes or washers to space out ring and use existing bolts

Make sure to post up a photo of the finished bike OP, everyone loves a singlespeed (well, I do).

Definitely will post pics. Yeah I like a single speed as well. Nice and simple and hard work 😂😂

So where do I need to use washers ? Will it not put chain ring slightly outta align ?

no, the chain ring mounts the same, you just need to stop the chainring bolts bottoming out as you tighten them with washers outside.

But even if it’s a mm or two out of line now it doesn’t generally affect it .

Be careful with the chain alignment and tension if you’re using geary rings, you really don’t want to drop a chain when you’re standing on the pedals… 😖

You can use the washers under the bolt head (ie between the bolt and the crank/chainring) so you’re giving the bolt more effective depth to thread into without spacing the ring away from the crank.

To be honest, it’ll be easier to buy a narrow-wide chainring from Amazon as they come with bolts that work on old school 104bcd crank sets. The ones I’ve bought needed filing down to fit in the middle ring position, but bolt straight onto the big ring position.
A £4 cog/spacer set anodised to match the chainring and your away for £14 plus tensioner.

Edit:. Shorten existing chain to fit, of find an old one.

If you are still looking for some bits and bobs I’ll have a look in my spares box. I can’t SS any more knees are shot. I’ve got a tensioner and some chains and rear cogs. Get in touch if you need anything. Happy to let you have it for cost of post.

“ Is is 2002 again? 🙂”

I resemble that remark!

Built my fancy new hardtail up as a singlespeed as an experiment, now kicking myself for not trying it years ago. Hills round here can be steep but never go on for that long, so it’s ideal. My bad knee seems to prefer it to gears!