SortaGrey

Made some measurement errors in the original post... reworking that math.

DaveSSS 

https://www.sheldonbrown.com/gloss_sp-ss.html#spacing

A properly dished rim is centered between the the dropouts, which also means centered between the faces of the axle ends that contact the dropouts or locknuts on older hubs with cones.

fietsbob

120 was what 5 speeds started out as, 6th required 6 more mm ,
8 speed needed 4 more mm .
which brings us to 130, which for road bikes it has remained..

Mountain Bikes to make the rear wheel, a little stronger and
add some drive train chainline shifting outward,
to clear the fatter tires went 5 more to 135, and stayed there..

as you move a dérailleur's hub to the right ,
the centerline of the rim moves more
towards a place where it is centered over the middle of the hub shell .
balanced spoke tension is Good, dishing to clear stuffing more cogs
into a cassette makes it more imbalanced ,
right side spokes shorter and tighter than the left.

wrk101

+1 Centered = rim centered between drop outs. Do you have a truing stand (not necessary, but handy). Old five speed was 120mm. 6/7 speed usually 126mm, 8/9/10 speed usually 130mm (racing bikes).

fietsbob

You measured the axle width or the frame drop out spacing?
if small top cog wont let the chain clear the frame you may need a fewmm of spacer on the right side,
then you have to go back and recenter the wheel to be in the middle again by half of what you added,

could add an equal amount to the left side, but then the overhang of axle would be shorter. so there may be less than desirable to hold the bike on the axle. then longer axles are installed ..

It is a balancing act..

SortaGrey

In my original post I goofed.. using 126 in place of 120.... 130 instead of 126. Must be the chest cold.. ... a bit under the weather today... which negated the bike ride. **&^*.... it.

I did measure on the axle.. end nuts.. which determine in the end the spacing of the dropouts when tight.

With my current 7 sp the last outside cog does clear the frame.. barely. Chain clears then too. As I noted in the original post.. it appears added spacing was just set over onto the NON drive side. From memory.. I believe the angle more severe onto the last 2 outside cogs.. than if some of the added spacing was split between the two sides.

Could be.. the core of my confusion is what must be design differences between rear hubs from 5 to 7 sp. I am using 5's and tricking them up to 7's. Likely the axle center is somewhat different 5 to 7.. changing how the dish effect is accomplished. For instance.. if a 5 has all of the spacing added to the DRIVE side... that side likely would be very flat.. no or very little dish.

YES.. a balancing act it is. Anyone know how/if the freewheels made for 7 speeds differ from the 5 speeds? Then.. freewheel width's vary I now find... again adding variables into spacing per drive line allignment.

I'm attached to my old Schwinn Traveler ( my winter rider ).. hence the messing around with the gear increase.. which certainly makes riding more enjoyable. Occurs to me now that a 7sp might fit into 120 spacing.. depending on freewheel width and how much dish is needed for the rear hub being used.

DID... lace up my first wheel the other day.. I find it very enjoyable to learn something per wheelbuilding. Need to figure axle spacing before I start to true and dish that wheel. I'll have to decide which freewheel... mount it.. and then set it into the dropouts and check the chain alignment.. then figure spacing.

SortaGrey

FORGOT.. Bill I do not have any kind of truing stand.. yet. Do see where something decent is needed to do a job right... for sure. Considering building that item given the winter being mostly ahead of us...

GOT... the wheel off my bike this morn and did some measurements. This rear is set at exactly 126mm.. I use a .080 washer on the end of the spacing to add that width for added frame clearance.. so plus that .08.

I measured the clearances and took some notes... I can see clearly now why the spacing is minimal on the drive side. Adding too much drive side would produce negative dish (if that is possible I doubt)... an un-buildable situation. Interesting stuff to me.. each rear hub a different animal per dimensions... wading thru this stuff has me understanding the why's and how's of dish.

Thing is... going to a 7 from a 5 is a drive line alignment problem. With the Shimano FW the outside chainring rubs on the chain in the high gear.. will even flip the chain off. Cant remember that happening when I had the Suntour Winner 7 on. But the BB and front rings are fresh so I cant see chging those out now. I need a front derailer cage replaced too.. might mess with that this aft.. .using high gear only on the large ring.

I have say 2500+ on this rebuilt Weinmann 27" rim I'm riding.. only one spoke went and that on the lazy side.. just a fluke I think. I'm planning to do a few low end wheel builds to get some experience.. and then build a Velocity rim with a decent hub for my winter rider. But I have no complaint on this LBS rebuild.. none. Has done well I feel all things considered.