Kontact 

You forgot that the axle got 2mm longer on the right and the feeehub shoulder moved left. 8 speed is only 3 to 3.5mm wider than 7.
And the chain got narrower, making more clearance for the dropouts.

icemilkcoffee 

Axle got 2mm longer on the right while the freehub body got 4.5mm longer on the right. That is the whole crux of the matter.
But the 9 sp cassette is fully 4.6mm wider. So there is simply no spare room for you to take up.
As to the freehub body shoulder- Shimano made several different styles of freehubs- some with deeper shoulders and some with shallower. The 6500 hub you showed above may have a shallower shoulder, but it has a spacer shim behind the freehub body, so it's probably a wash.
From 7 to 8 speed, the chain got narrower by 0.2mm, which is 0.1mm per side.

Kontact 

The wheels are exactly as I described. Where does it say the freehub is 4.5 longer between 7 and 8? Are you thinking of 11?

Haven't you noticed the left axle end is 2mm longer?

icemilkcoffee 

Sheldon Brown says you need a 4.5mm spacer behind a 7s cassette if you want to run it on a 8sp freehub body:
https://www.sheldonbrown.com/k7-7.shtml#stay
The 11 speed body is 1.8mm longer than the 8-10 speed

Kontact 

Sheldon also tells us that the 8 speed cassettes are 3.5mm wider than 7 speed HG cassettes. But an extra 1mm certainly insures your locking won't bottom out. Here's a 7 speed adapter that is 3.5mm:
https://www.performancebike.com/prob...hoCgNAQAvD_BwE

What you also seem to not understand is that there is plenty of extra room between the high sprocket and the dropouts. On several of my bikes I've added a 1mm spacer to give an odd derailleur spoke clearance. It isn't a problem. (Though, technically 7 on an 8 freehub is off chainline to the right. Ideally you'd have two spacers sandwiching the 7 sprockets, but putting a spacer under the lockring doesn't work.)

So, are 8 speed freehubs 4.5mm longer than 7? Absolutely not. That's just another bizarre factoid you've manufactured off a spacer reference. They are around 2.5mm longer, and have the low sprocket's shoulder pushed back about 1mm closer to the spokes.


As I've said from decades of experience swapping freehubs and building wheels starting in the 7 speed era, 5, 6, 7, 8, 9 and 10 all have the same double crank chainline. This had been accomplished by moving cogs closer to the spokes while moving both sides of the rear axle out equally. 3mm per side for 126, 2mm per side for 130. 11 speed doesn't have the same chainline, because it is only larger on the spoke side, so 11 speed cassette center is 0.9mm left of chainline.

icemilkcoffee 

If there was so much space on the right then how come the earlier generation of cyclists didn't space the hub over to the right to improve dishing? Why on earth would they leave so much on the table? I just looked up Shimano's document for FH61** rear hubs, which was made for both 120mm and 126mm:
https://si.shimano.com/en/pdfs/ev/HB...0%20R-0667.pdf
Look at item 11. This is a spacer on the right side. What does it say?
"Axle spacer 4.5mm for 5 speed"
"Axle spacer 10.5mm for 6 speed"
Exactly as I said - the entire 6mm was added to the right side when they went from 5 speed/120mm to 6 speed/126mm.

Kontact 

Why on earth did they use long reach brakes on old racing bikes? Why high flange hubs? Why make bikes with Italian BBs that unscrew themselves? The history of bicycles shows very slow and conservative development of just about everything - because bike riders are conservative. In specific, people probably were afraid of shifting too close to spokes at one time. They got over it.

That old Shimano hub shows that some hubs were converted that way. I'm not an expert in every historical component. Here's a good discussion about the wide variation in 120mm hub standards:
https://www.bikeforums.net/classic-v...s-126-hub.html

However, I am an expert in 7 and 8 speed hub conversions from Shimano, since I have converted a ton of them. And I just did the job I described above this past year. So you coming around to tell me that the 8 speed Shimano is 4mm wider on the right side is just plain insulting. If you held the hubs in your hand you immediately note the longer left axle. And, I actually got all the hub dimensions before I did my project from Shimano manuals and wheelbuilding databases.

You appear to have come across an idea that bothers you and then misinterpreted minor clues to suit your bias. But your bias that hubs just keep getting more and more dish is wrong. Shimano has lead all of these standards and have been very consistent in maintaining chainline and flange location. MTBs went to 135 hubs and 73mm BBs simultaneously because that added 2.5mm to both sides, crank and hub, preserving a consistent chainline. Campy did the same, with 130, but they started with a wider spaced 8 so they had room to go to 11 without screwing with dish like Shimano had to. Clearly they could have gone 8 with no trouble back in 1989, (like I just did with all Shimano parts) but they chose to create 130 instead, just to keep dish the same on the Dura Ace, Ultegra and 105 hubs they converted.

mrrabbit 

If it is mid-80s, it's likely intended for 6sp at 126mm.

It's not uncommon for a 126mm frames with hub removed to "shrink" down to 122-124mm.

What makes you certain it's a 5 sp / 122mm frame?

rccardr 

It’s an 84, and the manufacturer’s catalog specs it as ‘spaced for five speed at 121mm’. My caliper says 122.

rccardr 

UPDATE!
I obtained a 7 speed HG freehub and installed in on a DA7700 rear hub with the supplied spacer. Both freehub bases looked and measured up pretty much the same.
The 9 speed freehub was 4.5mm wider.
By removing a 6mm spacer on the NDS and replacing it with a spacer slightly over 1mm, the result is a 121OLD rear hub that will accept 8 cogs using 9 speed spacers and has the same centerline as the original hub.
Which I'm pretty sure means that it will build up into a wheel that is as strong as any other DA7700 rear wheel.
Feel free to correct me if I've missed something here.

Original 130mm DA7700 hub:

Note center line marked with sharpie

121 OLD rear hub with 7 speed freehub installed, Note center line is in the same place. I'll use a shortened axle when this is fully assembled.


No change in center line.

KCT1986

That looks good. Do you know what model the 7 speed body came from? Looks like it is HG Compact (11 tooth capable), that's kind of unusual. Does it have the deeper mounting penetration into the hub shell?

Let us know what the smallest cog to frame clearance is like when you get it finished.

Looks like it will build up to wheel with a reasonable L/R tension balance, a little over 50%.