Rear dropout distant for a fixed

[rich p]

My son has acquired an old steel frame which he wants to convert to fixed. I'm storing it for him and he has left a message asking me to measure the distance. Is it from outside to outside or inner to inner.
The measurements I've taken are 139mm and 124mm.
Are these compatible for a fixie?

 

[MartinC]

It's the Over Locknut (OLN) dimension that he wants - which is from the inside of one track end to the other. It'll determine the type of hub he needs. A standard fixed or track bike is 120mm so it looks like your 124mm figure confirms this.

 

[rich p]

Thanks Martin, what about the extra 4mm?

 

[MartinC]

It's just inaccuracy in the measurement or in the frame. The frame was built for 120mm hubs.

 

[Ian H]

It might be 126mm, the standard for derailleur geared bikes up to the mid-70s or so.

 

[Landslide]

Either tighten down the wheelnuts to bring the dropouts together, or stretch them apart to fit a wheel in. Old steel frames have enough spring in them that 4mm either way won't matter.

 

[rich p]

Thanks guys - I'll pass it on and post some pics when he's done it up.

This is it present

 

[jimboalee]

Either tighten down the wheelnuts to bring the dropouts together, or stretch them apart to fit a wheel in. Old steel frames have enough spring in them that 4mm either way won't matter.

126 from the look of the frame.

There is possibility to get a screw-on fixed sprocket and use a BB lockring with some threadlock.

Stretching rear dropouts to fit unsuitable hubs causes the inner faces of the dropouts to become non-parallel. Too much and the compression forces of the QR effectively bends the spindle.
If you are concerned, replace the spindle with a solid one which won't bend as much as a hollow spindle.
Or, when you'v got the distance correct, tweak the dropouts with a soft faced vice.

Good luck.

Can't see on the photo. If it's a good frame, it might have alignment adjusters in the rear dropouts. These are very handy to help set chain tension and get it repeatable.

 

[RedBike]

I would just go for a standard 120mm track hub, then use a washer or two to take up some of the 4mm's and get the chainline correct.

I'm sure 130mm, even 135mm track hubs exist but most are 120mm.

 

[rich p]

Here's a pic of it with some adjusting screws?

 

[swee'pea99]

126. For sure.

 

[swee'pea99]

Why does he want to know, in passing? Is he not planning to simply use the wheel that's on it now? That's what I'd do.

 

[rich p]

I'm not sure. I guess he's planning on getting some new ones. The ones on there are chromed.

 

[alecstilleyedye]

you'll have to be very precise with the chain length with such short dropouts. one of the advantages of track dropouts is that you can vary the gear (within reason) without having to split the chain. you won't be able to run a double hub with a sprocket on each side.

 

[MartinC]

It might be 126mm, the standard for derailleur geared bikes up to the mid-70s or so.

You're almost certainly right. Had it in my head that it was a track frame 'til I saw the photo.