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Hi all,

New to cycling, I'm looking to build a single speed for fitness/something to mess around on thats a bit different. Frame wise my friend gave me a Dengfu FM098 (http://dengfubikes.com/product/detail.php?id=119) following a failed attempt to get a project going. I already have a set of freehub wheels however I'm not really sure where to start with the crankset. I know the bike has a BB30 and thats about my knowledge. I've tried looking for guides but a number of sites seem to centre around a fixie build. Open to advice - was thinking about the sram s100 crankset but not sure if this will fit... Any ideas on simple guides to follow/advice or recommend products would be great. Ideally don't want to spend more than £100 on a crank.

Thanks

10 comments

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Redvee [238 posts] 2 years ago
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The biggest issue you'll have to overcome if using that frame is the chain tension and gearing. Ideally for a SS bike you need horizontal drop outs to slide the rear wheel backwards or forwards to get the chain tension spot on.
You might be lucky and choose what is called the magic gear which is a ratio from chainring and sprocket that needs to tensioner . Another option is to use a chain tensioner on the mech hanger.

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oldstrath [616 posts] 2 years ago
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oldstrath [616 posts] 2 years ago
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Might be better though to buy something off ebay with horizontal dropouts, or get something like a Pompino with track ends. Not as light, but if you're into fitness use rather than racing why worry?

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Jack Osbourne snr [440 posts] 2 years ago
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Turn that into a geared bike or punt it and get something with horizontal dropouts.

It can be done, but a frameset like that is not singlespeed friendly, certainly not as a novice project.

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Pauldmorgan [225 posts] 2 years ago
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Buy a Dolan FXE frame and fork: cheap as chips and very versatile: track or commuter as it has mounts for brakes,, 'guards and a rack should you need them.

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bashthebox [751 posts] 2 years ago
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Right, as so many have said this isn't the ideal SS frame - but assuming you want to make the Dengfu into the single speed, you will need a chain tensioner.
A quick google tells me there's not many BB30 track cranksets - SRAM omnium is the one, S300 is another...
Your alternative, if you don't want to buy a really expensive crankset, is to get a BB30 adaptor. Depending on which one you get, you'll be able to use Shimano GXP BBs and cranks, or old school square tapered BBs, which you may find allow you to get a pretty cheap crankset.

It's a minefield, all this bottom bracket and crankset malarkey. So many standards and variations on standards.

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surly_by_name [360 posts] 2 years ago
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You will struggle to do this for £100. But assuming you want to proceed, you will need:

A chain tensioner. Surly singleator (c.£30) best balance of cost and performance in my experience.

A crankset. BB30 cranksets hard to find, suggest BB30-BSA converter (c.£25) and then cheap chainset (you can get an Apex chainset on ebay without rings for somewhere around £30) cheapest option.

Chain ring (c.£45). Get one of the new(ish) narrow/wide rings - more expensive (and potentially a bit hard to find in 110/130bcd rather than the more usual 104/94bcd) but excellent for single speed. Really, I would not build another SS without one of these.

A cog. Again, Surly ones good because they have a broad base. (c.£25) Groove Armada from Planet X is similar and a bit cheaper at £15 (http://www.planetx.co.uk/i/q/SKOOSSGA/on-one-groove-armada-single-speed-...)

Some spacers and a lock ring. http://www.planetx.co.uk/i/q/SKOOSSKK/on-one-singlespeed-converter-kit

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bikeyourbest [23 posts] 2 years ago
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Sell that frame and buy a tracker with the proceeds. Then you can just put a flip flop wheel on the back, brakes and you're good to go.

Looks like a pretty decent frame so shouldn't be too difficult to sell. Besides, it has DengFu which everyone knows is 10x better than KungFu

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andyp [1448 posts] 2 years ago
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Keep the frame and get a White Industries ENO Eccentric hub  1

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pedalpowerDC [334 posts] 2 years ago
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Just to avoid confusion, please note that, contrary to an earlier post, there is no such thing as a "Shimano GXP BB". If you try to mix-and-match Shimano crank/BB parts with SRAM GXP parts, they will not work, and you'll have wasted time and money.

Both of the aforementioned options are 24mm spindle cranks, but the Shimano is a straight 24mm all the way across and the SRAM tapers. They are not interchangeable. If you choose to use an adaptor to fit a 24mm spindle crank to your BB30/PF30 frame, be sure to get the right one.