24" wheel conversion, Raleigh Shopper

Hello folks.

I have a Raleigh Shopper. It is my boat/travel bike. Looks silly, but actually not that bad to use. I mostly like it, but I can't resist tinkering!

What I am thinking about doing is fitting 24"/507 wheels, and maybe adding derailleur gearing; there are no decent 20 x 1 3/8" tyres available anymore, and I run out of steam up hills.

The front wheel would be catered for by replacing the forks with something off a kiddie MTB, adding a sleeve internally and extending the steerer, then an aheadset conversion. I could fit the Magura front brake I have in my parts bin then. Stopping won't be an issue with a 24" front wheel and a Magura!

The rear wheel almost fits, but the brake bridge will have to move. If I do that, I'll be able to cold set the rear triangle a bit wider than 110mm which it is now. This opens up all sorts of possibilities when it comes to more gears, which I might take advantage of. 20" wheels and derailleurs don't mix, IMO, unless you're happy to do a lot of cleaning.

I do realise it will have awful toe overlap, but I'm not that worried.

So here's my question. Would you be happy riding a Twenty without a brake bridge, or would you be worried it might all go horribly wrong? It's a strong little frame, but I am quite a big chap.

Re:

What about a pair of 20" mountain bike wheels ? they would bring derailleur gears and be far less work.

20" MTB wheels are quite a bit smaller than 20 x 1 3/8", which is what the Shopper was designed for. The bottom bracket would get even lower, and I would have pedal strike issues.

Also, it places the mech a bit too close to the ground, unless you use a stupidly short caged one. And if I go to the hassle of a derailleur setup, I want a reasonably wide range of gears.