Rear Drop Out Sizing

markos1963 · May 2009

Looking at my old Raleigh Record Sprint this morning I wondered about how the dropout is measured. Being its an old bike and has a screw on free wheel I presumed its a 126mm spacing so when I measured the frame I have got myself confused. It measures just over 121mm on the inside of the dropout and 130mm on the outside, so my queation is: what is it?

plug1n · May 2009

That would be a 120 - old 5 speed freewheel (or sometimes 6 in in the space of 5)

markos1963 · May 2009

It was a 6 speed when i got it, I've now changed it to a 7
So the dropout size is determined by the the internal measurment?

carl_p · May 2009

Hi Markos, my 1999 Olmo frame measures 130mm from the inside.

rickhotrod · May 2009

markos1963 wrote:

It was a 6 speed when i got it, I've now changed it to a 7
So the dropout size is determined by the the internal measurment?

Yes, it's the inside measurement. The corresponding measurement on the hub, is the outside of the locknuts.
7 speed is usually at least 126mm, sometimes 130mm or 135mm.

120mm is also what track bikes use.

If narrower 9 speed spacing was used you could fit 6 sprockets in the space of the old wider spaced 5. It would be nice if manufacturers offered 6 speed "retro style bikes" with 120mm rear hub/frame. 10/11 speed bikes are nice, but so is a retro bike in the stable!

markos1963 · May 2009

I suppose thats why I have to spring the frame open to get the rear wheel in after taking it out. I was thinking of making my own tool anyway to cold set the frame to 130mm so I could fit a more modern wheel.

Rear Drop Out Sizing

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