So I've measured hubs before to build wheels before, but for my next wheelset the hub is different. It's an older hub with spacers on either side, pictured below. How do I make sure the spacers are correct so I get the correct center to flange measurement?

what are you going to use the hub/wheel for? what is the current spacing locknut to locknut?

it looks like it may be spaced for 7 spd. do you know what freewheel was on it?



if your intending to use it for a SS, I would swap some spacers around and make it symetrical

use a set of measuring calipers.

Start by deciding what freewheel you're going to use. Check and/ respace the hub so the distance from the freewheel shoulder to the locknut face is the same as the freewheel width +3mm clearance. Or lightly spin the freewheel on and fit the hub into your frame and make sure a chain wrapped over the outermost sprocket clears the frame with about 1mm clearance.

That's the spacing you need or want, and you can now measure the hub the usual way. Don't forget to confirm that the OLD matches your frame.

There's no need for the trial and error that has been suggested so far. There are clearly published specs:

Here they are:

A = Freewheel Stop to End-of-Locknut
B = Drive-Side-Flange-Center to End-of-Locknut
C = Outside-of-Locknut to Outside-of-Locknut

Regular 5 and 6 Speed

A = 29.00mm for 5 Speed
A = 35.00mm for 6 Speed
C = 120.00mm-122.00mm

Narrow 6 Speed, 7 Speed and 8 Speed

A = 31.00mm for Narrow 6 Speed
A = 36.00mm for Narrow 7 Speed
C = 125.00mm to 127.00mm

A = 40.50mm for Narrow 8 Speed
C = 130.00mm or 135.00mm

Most folks who want to build a classic 80s 126mm 6/7 Speed rear hub will simply go:

A = 36.00mm
B = 43.00mm to 44.00mm
C = 126.00mm to 127.00mm

IMPORTANT NOTE:

Get the freewheel side perfect as possible. That side must be correct.

Hold the hub and ruler "vertically" when reading your results to get a good read.

Use the non-drive side as your "buffer", "fudge" or "play loose" side in order to get "C". "C" doesn't have to be perfect. Most of my 6/7 Speed rears end up being 126.50mm when I'm done.

=8-)

Thanks mrrabbit, this is what I needed to know but couldn't find it.

You are welcome!

=8-)

I believe you have this a bit backwards. Narrow 6-speed freewheels (Ultra-6) were close to 5-speed in overall width and fit on 120 mm OLD hubs. Regular spaced 6-speed freewheels were close in width to 7-speed freewheels and fit on 126 mm hubs. 8-speed freewheels (the few ever made) were wider still and used 130 mm OLD hubs just like 8/9/10-speed freehubs.

And that matches the specs on the Campy instructions that are with my NOS yet-to-be-built Tipos

You are free to argue with Mr. Sutherland, Jobst Brandt, and just about anyone who has been around longer than I have who has been involved in documenting standards and common industry practices over the last 5 decades...those are their numbers...not mine.

Sure you can fudge the narrow 6 on 120-122mm...but "A' is the spec that keeps you out of trouble...that's why I made it clear - the freewheel part is what has to be right - "A".

=8-)

Saw your signature...are you getting affected by the WoolJersey "falldown" like the folks over at CR as well?

=8-)

Hillrider is right, 6u or narrow 6 freewheels use 7s spacing and were made to offer 6 gears in the width of 5 for older 120 hubs. 6s or standard 6 has the spacing of 5s and is roughly the width of a 7s freewheel for 126mm hubs. (I've sold enough of these to know, and still have a bunch of 6u freewheels if anyone wants one).

Of course individual hubs may vary which is why I usually tell folks how to measure for themselves rather than publish 2nd hand specs which are prone to misprints and typos.

Here it is again, note the markers I added regarding "A":

Regular 5 and 6 Speed
A = 29.00mm for 5 Speed
A = 35.00mm for 6 Speed <<<<
C = 120.00mm-122.00mm

Narrow 6 Speed, 7 Speed and 8 Speed
A = 31.00mm for Narrow 6 Speed <<<<
A = 36.00mm for Narrow 7 Speed
C = 125.00mm to 127.00mm

No "au contaire" needed...

=8-)

OK, one more try. The "A" dimensions appear to be right but the values for the two different 6-speed types, Ultra and Standard, are listed in the wrong order. A narrow 6-speed with it's A-width of 31.00 mm will fit on a C=120 mm OLD hub. The standard spaced 6-speed with it's A-width of 35.00 will not fit a 120 mm hub but uses a C=126 mm OLD hub.

+1. That was the whole point of Suntour's Ultra 6 freewheels. They had six cogs in roughly the same space as a standard five speed freewheel had five, and were designed for 120 OLD hubs.

Sutherland's 5th Edition, Page 10-5
Sutherland's 6th Edition, Page 10-6

=8-)

From Sheldon's site:

In the 1970s, there was a move toward 6-speed freewheels. These were of two types:
"Standard" spaced 6 speeds had sprocket-to-sprocket spacing the same as the existing 5 speeds, around 5.5 mm
Standard spaced 6-speeds required increasing the frame spacing to 126 mm, aggravating the problems introduced with the move to 5-speed, but still providing satisfactory service in most cases.

"Ultra Six ®" spaced 6 speeds used a closer spacing, around 5 mm. This permitted an Ultra Six ® freewheel to directly replace a standard 5-speed unit on a 120 mm hub.............

Typos happen.

Glad to see you understand why the published numbers are what they are...

I almost want to take a Chosen A1012 and "chop it" so to speak, make a YouTube video of it to demonstrate how to make a Regular 6-speed 120-122mm OLD rear hub...

Chosen A1012 NDS race is more inboard which makes it a good candidate.

=8-)

What are you talking about?

???

Puzzled by your statement "glad to see you understand why the published numbers are what they are." What I understand is that there's an apparent typo in Sutherlands on this subject.

Sutherland's in NUMBERS:

Regular 5 and 6 Speed
A = 29.00mm for 5 Speed
A = 35.00mm for 6 Speed <<<<
C = 120.00mm-122.00mm

Narrow 6 Speed, 7 Speed and 8 Speed
A = 31.00mm for Narrow 6 Speed <<<<
A = 36.00mm for Narrow 7 Speed
C = 125.00mm to 127.00mm


Sheldon Brown in WORDS:

In the 1970s, there was a move toward 6-speed freewheels. These were of two types:
"Standard" spaced 6 speeds had sprocket-to-sprocket spacing the same as the existing 5 speeds, around 5.5 mm
Standard spaced 6-speeds required increasing the frame spacing to 126 mm, aggravating the problems introduced with the move to 5-speed, but still providing satisfactory service in most cases.

"Ultra Six ®" spaced 6 speeds used a closer spacing, around 5 mm. This permitted an Ultra Six ® freewheel to directly replace a standard 5-speed unit on a 120 mm hub.............


They both are saying the same thing. Sheldon of course notes the problems introduced by Regular 6 and the application of Ultra-6 to older 120-122mm hubs.

As I stated back in my reply to FBinNY - there's no need for "au contraire" here.


=8-)

No typos...

=8-)