Started this project thinking I could just do a new drive train, tubes, and tires. Well turns out 500a tires are a nightmare. I converted to 20 inch. Then I needed a new crankset, threadless adapter, etc. The crux though I think will be the brakes. Any trick out there? Drop bolt won't work due to fender. 92mm extra long brakes are still too short. Do we they make a mount that I can drop it down under the fender? Arm extender things? Or do I need to back track and coaster brake it? Thanks.
by Catbuttholess
19 Comments
I’m sorry, but going down this far in wheel size is just a bad idea. The bottom bracket for example will be so low you will constantly be striking the pedals on the ground if you ever attempt to pedal through a turn.
Edit. After a bit of research, perhaps changing to 20×1 3/8 rims with a 451mm bead seat diameter would be better than normal 20″ wheels with a 406mm bead seat diameter. 500a is 440mm at the bead seat.
The other option is drum and coaster brakes drum brake on the front wheel and coaster or drum on the back.
500a has an ETRTO of 440mm. 20” wheels have an ETRTO of 406mm or 451mm. Which means a 34mm smaller diameter or 11mm larger diameter respectively. Looks like you got the wrong 20” wheels 😅. Unfortunately brake calipers don’t come longer than you currently have nor would you want them longer (worse braking). Your best bet is to replace the wheels (again) with 451mm 20” wheels & tires. 451mm 20” tires are more limited and the width is typically narrower which would benefit you in fitting slightly larger diameter wheels.
You didn’t ‘convert to 20 inch’ you put the wrong size wheels on.
Put the correct size wheels on and the brake pads will line up with the rim.
Dude, if you’re set on that wheel size just put a coaster brake on. Even it you get a caliper with long enough arms to reach the brakes will always suck. They will lose power due to the huge amount of flex and rim brakes on steel rims are almost useless anyway.
https://preview.redd.it/edq8pcnt7i3h1.jpeg?width=300&format=pjpg&auto=webp&s=c0131fce827303a115c1e6f5dd8a67f7a773c02f
There are offset brake shoes that can lower the position by 10mm, but I’m not sure if that will be enough.
have you considered using 22″ BMX wheels? those are fairly readily available
Convert to coaster brakes? You’ll need to respoke the wheels. You could just make due with the rear brake and ignore the front. It’s not like you’ll be bombing any hills on this one.
Bin that. It’s not going to work.
Of all the things that are not worth it putting money into this project is pretty close to the most not worth it.
Jump deeper in to the hole and go for a disc brake conversion while you’re at it. Or maybe se if you can squeeze a set of 24” inch wheels in there
You don’t need brake help. You need wheel help.
If a solution exists that doesn’t involve either pilutting the correct size wheels back on or paying multiple times the value of the bike for a framebuilder to modify the bike to use those I have never seen or heard of it in over 30 years in the trade.
Looks like you have the wrong wheels on that French bike. Maybe look for racing bmx wheels 20×11/8 tires will work much better on that French bike. French bicycles use different measurement system than the Ole USA.
What an I looking at??
A wheel for ants?
[https://www.bicycleheaven.org/products/bicycle-tire-white-wall-20-x-1-38-37-440-fit-french-italian-bikes](https://www.bicycleheaven.org/products/bicycle-tire-white-wall-20-x-1-38-37-440-fit-french-italian-bikes)
I did manage the same conversion on an old Dawes Kingpin folder using the widest tyres I could fit. It wasn’t as bad as some people are saying, but it was a hack. Front caliper brake with huge drop was off a BMX bike, rear was a V-brake converter that clamped on with hose clips. I have no idea where I’d source either of them now.
I think this is not worth doing unless you can source the correct tires, even then it’s dubious how worthwhile this would be.
Bike doesn’t look to be in good shape. It wasn’t even a nice bike to begin with. Coaster brake won’t work as it doesn’t have the tabs to support the brake arm thingy. Smaller crank arms will make it pedal horribly. Not to mention compatibility with seat posts, stems, bars and hub spacing. I don’t think this project is worth sinking any more money into.
If we wanted to bring this up to speed, we’d probably be in the $750 neighbourhood. And after all that we’d still be riding a Peugeot folding bike from 1978 that we can’t get tires for.
You’re trying to put 20 inch wheels on a road bike? Why?
Wrong wheel