Dura-Ace FC-7400 Crank Query

Hi there,
I wonder if somebody can offer some advice, I'm putting together my first single-speed and recently picked up a used but clean Dura-Ace FC-7400 set of cranks + bottom bracket (but with no chain rings), the cranks are 165mm and 130BCD.

I don't think these are track cranks but were designed more for road use, despite that would these still be useable for a single speed? I'm guessing I'd need smaller bolts for the chainring and a 3/32" chain?

Or is it worth waiting/saving up for the track equivalent crankset (FC-7600)?

Any advice welcome :)

Aaron

They are road cranks 7600 are completely different track cranks which are v nice

The chainline on the double road cranks (7400) will be too far outside for a normal track hub on the outer ring and too far inside on the front one ring

You can but surly fixed/free hubs with chain lines to match road cranks, but they are wider than track hubs and fit wider road dropouts, such as road frames & road frames converted to ss… not track frames

You can use a shorter bb to bring the cranks inwards to match a track hub chainline but you may find bits of the crank foul the frame

Depends on the bb width and the rear hub chainline, but usually the inside ring on road cranks has a chainline close enough to standard track chainline to not be a problem (41mm vs 42mm IIRC).

You'd just need narrower chainring bolts and a chainring/chain width the same or bigger than what's on the back.

7400 is a really nice crankset, would be completely fine for a commuter/beater.

I'm currently experimenting with a similar set up. I've not actually cobbled it together yet but I've spent far too much time and money on trying to get a DA road crankset to work on my fixed gear. From a quick eyeball, the chainline should be alright and hopefully fixable with spacers if it's not spot on. I'm hoping to get it all built up in the next few days so will report back!

Thanks for the great information, interested to hear how you get on with your DA road crankset build. The 7400 are lovely looking cranks, I just wish the track version would be cheaper.

The frame I'm using is a well worn Mercian vincitore by the looks of it, but it is equipped with dual brakes bosses, mud-guard eyes, front fork light attachment(?) and cable run eyes. Unusual beastie but perfect for a commuter single-speed/fixie, as it has the track style drop outs. The plan would be to use a flip flop wheelset, but I don't know if that would impact fine tuning of the chain line if combined with the road crankset (would definitely have to fiddle with the chainring bolts). Might be easier to just seek a cheap track crankset.

I got totally mixed up. My cranks are a fair bit more modern and Hollowtech, rather than square taper. I believe @AlexD did something similar to what you're trying to achieve so might be able to offer some tips!

As you say, you will probably need shallower chainring bolts to just use one chainring.

In terms of getting the chainline right, it's just a case of working out what length square taper bottom bracket to buy. Pretty sure DA 7400 cranks use a 112mm length BB.

If you have the chainring on the outside position of the cranks, it will put the chainline at 46mm. Generally a track hub is going to give you a 42mm chainline, so you just need to get a bottom bracket that brings the cranks in by 4mm, which means an axle thats 8mm shorter than the standard 112mm one.

So 106mm. Which I don't think you can get, so 107mm which you can.

I'm pretty sure thats right, but I did the maths in my head and I'm bad at maths, so maybe someone else can back me up :-D

112 - 8 = 104

How dare you expose my poor mathsing!