Change rear hub from freewheel to freehub/cassette

[RMMW]

I have a very old Univega road bike whose rear hub is failing. Instead of just replacing the freewheel hub with another of the same, I want to "modernize" it by changing to a cassette style. The reason is that I want to customize the gears to make the lowest gear an ultra-low, big sprocket for climbing steep hills. My legs are much older than the bike and no longer have the strength to power up steep hills with the existing low gear. I can't find a freewheel hub with such a low gear. However, I do see them on mountain bikes but those are cassette style.

So my question to this group is: Can you recommend a cassette style hub model?
The existing hub is a QR but I would not mind needing a wrench to do repairs. The distance between the rear "forks" is 126mm. The wheel is 36 spokes, with rim brakes. I do not care how many gear sprockets there are, as long as it fits in the fork. (The existing derailleur is not index style, but I will probably need to change it also, to get it to lift the chain up onto the the big diameter sprocket.) I do see a cassette hub that should fit OK, but it also has provisions for mounting a disk brake; I have rim brakes. If I just omit installing a disk, will the distance between spoke flanges of the hub be sufficient for lateral wheel strength?

 

[iluvmybike]

You can replace the hub and rebuild the wheel. However yuo have the problem of finding a hub for a 126mm dropout width - bit like hens teeth. Modern ones are all either 130mm or 135mm. Perhaps yuo'd be better changing the chainring sizes instead - lot easier to do

 

[mickle]

What size rings do you currently have? And what are your largest and smallest sprockets?
I'm running a 130mm hub in a 126 frame with no issues. If it's a steel frame you could even have it 'adjusted' to accommodate the extra 2mm on each side. If you can be bothered. The primary concern is that your dropouts should be parallel when clamped to the new hub.

 

[DCBassman]

As per @mickle. Just buy a 130mm 8-9-10 speed freehub wheel. How many rear sprockets? And what type of shifters? If friction downtube, great, the rear mech might do 7 but might baulk at 8.
Definitely more information about the current spec needed, but definitely do-able, I would say.