Upgrading a used road bike (freewheel)?

First off, a quality bike with a 5-speed freewheel will be old. Say 30 years or more.

Unless its some strange recent retro quality boutique build.

And it'll most likely have a 120 mm dropout width.

Meaning the space where you insert the rear wheel is 120 mm between the inside faces.

Most 6/7-speeds have a 126 mm dropout width.

Simply forcing the rear wheel in there is usually possible, with a bit of brute force, but not recommended. Dropout alignment will be off, which can contribute to axle breaking, bearing wear and sloppy shifting.

Not that the last is likely to matter much, as 5-speeds tended to be friction shifting.

Steel frames can be spread, called cold-setting, to accept wider rear wheels.

And if done right, and followed with a dropout alignment is quite accepted practice.

Doing this"upgrade" would also require adding axle spacers, redishing the wheel and maybe even having the axle replaced with a longer one.

There are freewheels with what's called "Ultra" spacing, which would allow you to use a 6-speed f/w in a 120 mm frame.

If it's a less old, low-end BSO - Bicycle Shaped Object - masquerading as a road bike, it might have a 130 mm dropout width. And while I've seen RBSOs with 6-speed rears and 130 mm dropout width, I've never seen one with a 5-speed rear.

If you have a 5 speed freewheel chances are the drop out spacing on your frame is 120mm.

A 6 or 7 speed FW will not fit.

You can still buy new 5 speed freewheels

But going to a 6 speed will involve buying a new wheelset and squeezing into the frame or spreading the dropouts.

Suntour made ultra spaced 6 speed freewheels that were designed to fit 120mm frames.

You can find them on eBay sometimes for real cheap if you're patient. I picked up a new old stock one for $10 not too long ago

Most five speed bikes can easily be fitted with seven gears as have fitted a modern 7 speed hybrid wheel to a '79 road bike. So have replaced the 5 speed wheel, a 27 inch, with a modern 7 speed 700C wheel. Shimano do derailleurs, a 7/8, for as little as £25 so problem there.

Why not buy a bike that is less then 10 years old and has an aluminum frame. You do not want to upgrade a bike that is junk to begin with.

I agree with John M. A newer "old" bike will ride better. AL frame is lighter than steel. Freehub/cassette is better than freewheel. Although quill stem had more adjustability, a threadless system is lighter and requires less maintenance. The rims are way better than your old squeaky ones. And dual pivot calipers are better than single pivot.

There will not be enough room. It would be better to spend the money you will have to spend on upgrades to just get a better quality bike to begin with.

yes maybe

though it will be way too much trouble if you do the work and too much money if someone else does

it would never be worth over $40 no matter what you do

so

first i would have to ask, what is the real goal, what problem are you trying to solve?

wle