Frame spacing on rear dropouts..

[janus77]

Just wondering about rear dropout spacing. Seems track frames normally have a 120mm spacing, whereas a road frame might be more like 130mm?

Question i have is if you're looking at putting a track hub on the rear of a road frame, is the best option to get a longer axle and some spacers, or to try to squeeze the frame to fit the hub?

I'm assuming forks are much the same spacing be it track or road..?

[Kid_Carbine]

The way I remember it, single speed spacing with freewheel or fixed was 110mm, then 120mm for five speed clusters or six speed if 'ultra' spaced.
Next came 126mm for regular six speed blocks, or seven speed if ultra spaced.
After that I don't care as nobody 'needs' more than a six speed block anyway.

[531db]

The way I remember it, single speed spacing with freewheel or fixed was 110mm, then 120mm for five speed clusters or six speed if 'ultra' spaced.
Next came 126mm for regular six speed blocks, or seven speed if ultra spaced.
After that I don't care as nobody 'needs' more than a six speed block anyway.

110mm: Old Track/single speed
115mm: 4 speed
120mm: 5 speed (and 6 speed Suntour Ultra), also 'modern' track.
126mm: 6 and 7 speed
130mm: 8, 9 and 10 speed
135mm: MTB

[531db]

Just wondering about rear dropout spacing. Seems track frames normally have a 120mm spacing, whereas a road frame might be more like 130mm?

Question i have is if you're looking at putting a track hub on the rear of a road frame, is the best option to get a longer axle and some spacers, or to try to squeeze the frame to fit the hub?

I'm assuming forks are much the same spacing be it track or road..?

Use spacers to take the axle out to 126mm or 130mm as required.

It's not to hard to spread a frame out to accomodate a wide hub axle, but squeezing it in is much more difficult and more stressful to the stays.

[janus77]

ok, using spacers I understand, however if a hub is 120mm, wouldn't the axle be too short? I mean there wouldn't be that much extra axle to space it out would there?

Guess I should check the manufacturer specs of hubs for axle length to see how far it will accommodate spacing.

[familyguy]

ok, using spacers I understand, however if a hub is 120mm, wouldn't the axle be too short? I mean there wouldn't be that much extra axle to space it out would there?

Guess I should check the manufacturer specs of hubs for axle length to see how far it will accommodate spacing.

Always get a new axle if you're going wider.

Jim

[janus77]

http://cgi.ebay.com/NOS-Gold-anodize-Al ... dZViewItem

Would something like this work for a fixie build - 700c wheels?

[531db]

ok, using spacers I understand, however if a hub is 120mm, wouldn't the axle be too short? I mean there wouldn't be that much extra axle to space it out would there?

Guess I should check the manufacturer specs of hubs for axle length to see how far it will accommodate spacing.

Axle length is critical. To space out to 126mm, you need extra axle space of 3mm each side, to space out to 130mm you need extra axle space of 5mm a side.

I've just run a quick ruler over the axle length of some of my 120mm spaced track/fixed hubs.

Sanshin Pro 160mm
Sanshin Pro NJS 155mm
Velocity/Formula 156mm
Bianchi/Formula 156mm
Campag Record 149mm and 152mm.

I also measured some steel road and track dropout widths mostly 4 to 5mm each side, although cheap pressed steel was 3mm, and alloy can be thicker at 6mm +.

Also found that most decent track nuts are 12 to 13mm wide.

So, say for a steel frame with a 130mm spacing and 5mm wide dropouts:

130mm spacing
10mm dropouts
25mm nuts

165mm total.

Or a steel frame with 126mm spacing and 4mm dropouts:

126mm spacing
8mm droupouts
25mm nuts

159mm total.

However having said that I'd take my 160mm Sanshin axle out to a 130mm spacing if necessary on 4mm dropouts for road use, I would not be overly concerned with a calculated 1.5mm axle deficit per side, that's only a thread per side in the track nuts and I'm not Theo Bos

[janus77]

thanks for that, very useful info!