rccardr 

Have acquired a new mid 80’s frame orignally intended for a five speed rear hub,so dropouts spaced at 122mm. Played around with a 130mm DA freehub style hub and got it down to 123mm-close enough. I know this will wreak havoc with dishing the wheel and put more strain on the NDS spokes. Question is, has anyone actually tried this and,if so, what were the results?

Andrew R Stewart 

Underdishing is what many wheelbuilders do during the wheel making process. Dish to far before max spoke tension id attained and only tighten the LH side to bring back to centered dish. I see no reason, WRT spokes, that this won't work. Now how will the frame/chain clearances work out... That you'll have to find out.

I have done much of this on many shop repairs when the first choice wheel is unavailable. Often the axle will also need cutting down in length. Andy

rccardr 

Thanks, Andy.
Have already cut down an axle down to fit.
If the chainline spacing won’t allow a full width cassette, can run some spacers behind it to bring it out some and use 9 speed spacers to allow enough cogs.
Friction shifted, so spacing isn’t dependent on indexing and I have bags of cogs and spacers to play around with.
All this to avoid a freewheel and keep the stable pretty much all HG.

mitchmellow62

The following thread talked about specific shimano hubs that are best for 10 speed on 126 spacing. Not sure if it has any applicability for you but here it is: https://www.bikeforums.net/classic-v...b-success.html

FBinNY 

The issue will be the amount of dish the wheel will call for.

Dish means uneven tension between the flanges, and that can be predicted before building.

The tension difference is proportional to the ratio of the center to flange differences. (for more accuracy, subtract the rim spole hole offset). So, for example, if you end up with something like 30 & 60mm the tight side spokes will be twice as tight as the left.

Once you know the tension ratio, consider compensating by reducing the left side spokes' cross section accordingly.

Of course if the rim is too close to the right side, the bracing angle will be too little to built a strong wheel. IMO the crap shoot guideline for minimum right CTF is 20mm or so.

BTW as the bracing angle shrinks, you'll want to stiffen the wheel by using thicker spokes. You might consider something like 2.0 plain gauge spokes on the right & 2.0/1.7 spokes on the left.

icemilkcoffee 

Which DA hub is this? If it’s the 7700 hub you could swap the 8-10 speed freehub body for the 4mm shorter 7 speed freehub body.

Kontact 

You're getting very close to having almost no bracing angle on the drive side, which means that your tension on the non-drive side will be near zero. A wheel like that will break spokes quickly.

If you are cool with using 9 speed spacers, swap the 8 speed freehub body for a narrower 7 speed. That will move the flanges up to 4mm to the right, giving you a good bracing angle on the right and increasing tensions on the left into a useful range. Eight cogs with 9 speed spacers will fit.

rccardr 

It's a DA 7403 hub, which has a completely different freehub mounting system than later hubs. DS center to flange is right at 20mm. . A 7400FH 5-6-7 speed DA freehub would fit and that is certainly an option. Alternatively, I can use a Tricolor hub and a later 7 speed freehub, resulting in 126mm spacing. Could probably fudge that a little with spacer changes to less than 126.

Was pretty stoked about using this 7403 hub, but when I realized I'd be dishing 7mm away from optimum stock dimensions, I got a little nervous about wheel strength.

HillRider

This sounds like the opposite solution to the usual hub OLD/Frame OLD mismatch. Generally it's solved by widening the frame, not narrowing the hub. Assuming your frame is steel, widening the rear spacing to at least 126mm should be easy.

rccardr 

Yes, that is one potential answer, although I’m pretty sure I can either squeeze a 126 in there without cold setting or swap a NDS axle washer out of a 126 hub to make a 124.
I’m gonna go play with some parts now.

KCT1986

Is this measurement (in Bold above) the 7403's stock configuration?

Based on the stock setup, you may be able to squeeze out 1-2 mm from the drive side by using a thinner washer and 3.5mm locknut. This would put the edge of the freehub body really close to the inside face of the dropout. If you plan to use a Uniglide smallest cog (no lockring) and do some respacing of the cassette rings & spacers, you may have enough space for the chain to fit with no rub on the dropout or seatstay. This would be dependent on the design of the frame/dropout and the size of the smallest cog.



By squeezing out a couple of mm from the DS and the balance from the NDS you should be able get a tension balance of a little under 50%. You may want to consider using an asymmetrically (offset) drilled rim. This would help to balance out the dish.

Kontact 

I had an old Cannondale that could not be cold set and was painful to cram a 130 into. But I checked the specs on current Shimano 11 speed hubs, and using an 8/9/10 freehub with a 126 axle gave me exactly the same flange offset locations as 11 speed. So that's what I did, and it worked perfectly. I would definitely do it again for any non-steel 126 spaced bike that I wanted more speeds.

KCT1986

As an owner of a 126mm OLD CDale, interested in what Shimano 11 speed freehub and body you used to get to 126mm. Also, how was the dish after the change?

For the OP's question, could the change that you made be increased further, closer to the 123mm that the OP is inquiring about?

rccardr 

Not sure I could get any thinner on the DS end nut without causing other problems. That 20mm measurement was in the hub’s altered form.
Ultimately, decided that there were more reasonable and logical answers out there.
At this point I’ve purchased a used 7400 freewheel hub that’s 126mm and am sure I can pursuade it to drop down a couple mm.
Also need to disassemble a tricolor wheelset rear hub to see if the 7 speed HG freehub avaiable to me jas the correct base sizing to transfer it over. If so, that’s another 126 or narrower option.
Thanks to all for your kind suggestions!

Kontact 

To be clear, I put an 8/9/10 hub in the space of a 7 by copying the dish from an 11 speed hub.

When Shimano introduced 8, the went to 130 and moved the inner cog closer to the right flange. This resulted in the dish of the wheel being identical to 126mm 7speed wheels. (The hub bodies usually were identical, just the freehub and axle/spacers having changed.) When they came out with 11, Shimano gave up on their previous dish standard and made room for a wider freehub by moving the hub body to the left, eliminating one left axle spacer and losing some bracing angle in the process.

What I did was shorten the axle on the left and re-dishing to the 11 speed standard. That made just enough room for the 8/9/10 freehub while staying at 126mm. Shimano was too conservative about dish to do that in 1989, but apparently not so concerned about it in 2012.

To go to 123mm you might be able to shave 1mm on the driveside, depending on your lockring and dropout, but you'll definitely need to take 2-3mm off the left side - which means further dish is required. I'm not saying 123mm is going to be perfectly fine, but it will be much better than trying it with an 8/9/10 freehub. It won't be as solid as even an 11 speed hub.

KCT1986

Thanks for the info.

So you ended up increasing the dish to the dimensions that are common on the latest Shimano road freehubs. Usually this is just under 50%, based on how Shimano measures, outside of flange to outside of flange.
When converting their measurement to center of flange to center of flange, a couple of % more dish, about 46-48%.

Mc2

I’ve done the 126mm to 130mm cold press on a 1979 frame, then successfully installed new Campagnolo Chorus 12 gear cassette, along with Campagnolo Chorus 12 derailleur. Worked and rides like a charm. Even kept the original cranks and chainrings. See YouTube for videos on the cold press method

Kontact 

I believe you mean "cold set".

icemilkcoffee 

This is not correct. When Shimano went to 130mm/8 speed, they increased the OLD from 126mm to 130mm. ALL of this increase went to the freehub body, which increased by 4mm. So in fact the dish was made worse when Shimano went to 8 speed.
In fact, at every step of the way, from single speed (perfect- no dishing), to 5 speed/120mm (dishing was introduced), to 6/7 speed/126mm (5.5mm of that added 6mm went to the freewheel side), dishing got worse. Then to 8 speed, then to 11 speed. At every step of the way, the dishing got worse than before, and the deal with Satan got extended more and more.

Kontact 

You're wrong.

You haven't read what I wrote or measured these things yourself. You don't know what you're talking about. Here's a database:
https://spokelengthcalculator.com/da...tring=dura+ace
Once you subtract 2mm for the right half of the 4mm axle difference, the listed offset differential for 7400 7 speed and 7403 8 speed is 0.7mm.

And that's because (as I already told you) the cassette shoulder was moved in about 2mm closer to the flange when they went from 7 to 8. You can look down on an assembled 7 speed bike and see the bigger gap between spokes and low cog. You can also look at the shoulders themselves:


7 speed

8 speed

Where do you get your facts from?

Kontact 

I had missed the rest of the nonsense in your post. Dishing and chainline haven't changed between 120, 126 and 130 10 speed. The added width was always added to both sides of the hub. It should be freaking obvious that the move from 5 to 6 didn't require 6mm on the drive side. It was 3. 130 got 2mm per side.

Did you get you info from Alex Jones?

grumpus

Don't bother, just set the dropouts to 130 mm (assuming it's a steel frame).

icemilkcoffee 

Actually the 7 speed freehub body is 4.5mm wider than the 8 speed freehub body. In order to do what you are suggesting, you would have to move the end of the freehub 2.5mm closer to the locknut. And there simply isn't 2.5mm to spare on most road bikes on that end before the chain rubs the seat stay or the small cog rubs the chainstay.
Also- go and look up the Shimano diagrams for the FH1055 vs FH1056; and FH6401 vs FH6402. These hubs have identical hub bodies and similar HG freehubs (aside from the lengths of the freehubs), so they are good for direct comparison. For the FH105*, the left lock nut got moved out 0.7mm. For the FH64**, it was 1.1mm. So that means the right would have moved by 3.3mm and 2.9mm. Definitely not symmetrical. The dishing definitely got worse.

icemilkcoffee 

The 6 sp freewheel is 5.5mm wider than the 5 sp. And they used the same width chain. So how do you jam a 5.5mm wider freewheel into a space that only got larger by 3mm? Obvious?

Kontact 

By putting the inner cog closer to the spokes. Same thing they did with 8. Thats why chainline never changed - the cogsets always got bigger on the inside and outside, keeping the same center.

You should measure stuff. I have.