Choosing parts for wheel build on a cargo bike conversion I am using an old Xtracycle Free Radical to convert my hybrid 90s Specialized CrossRoads to a cargo bicycle.

The Free Radical was originally designed for 26” wheels, but many people used them on 700c bikes using disc brakes. 

My plan is to stay with the 700c tires, but move to disc brakes because the 26” to 700c V-brake conversion kit was discontinued a long while ago, and the FreeRadical tail does have an area to mount disc brakes from.

My rims are old Araya 700c-PX 45 rims, but years of using the bike with pad brakes has deeply carved out the rims, so I fear that I have no choice but to replace them both in this project to stay safe. In order to cut down on costs, I’m going to build the wheel set and put together the disc brake in the rear. I’m reading Sheldon Brown’s Wheelbuilding site, but I am having a hard time figuring out what components to use to build these rims and the rear disc. 

Here are some details about this build:
I weigh about 125 lbs. The Xtracycle can haul up to 200lbs (additional). I doubt I’ll ever haul 200 lbs, I’m mainly going to be getting groceries and running errands with it. The Xtracycle can only take a disc brake with a 203mm rotor. I’m attempting to build this economically, so I’m hoping for decent quality, at an affordable price that is lower than buying pre-made new wheels. I do have access to a bicycle co op where I may be able to harvest used parts. 

Do you have any suggestions on what type of rim, spokes, hub, rotor and brakes I should use?
Do you have any suggestions on what type of rim, spokes, hub, rotor and brakes I should use?


For cargo bike purposes you obviously should prefer sturdiness over light weight for wheel components. 

A wider rim would allow  you put wider tires which can help with high cargo weight. For 700c wheels, rims that can accomodate tyres of at least 40 mm width are reasonable.

Previously, one would recommend going with bigger number of spokes per wheel in such wheels — 48 if you are really dedicated to find them as not many vendors offer them, 36 if possible, 32 if no other option, and avoid modern rims and hubs with less than 32 holes. However, I am unsure if this advice keeps up with the times, and it may well be that 28-hole rims are as good as 32-hole these days.

For spokes, use the thickest straight-pull available. For nipples, use brass ones.

For hubs, use compatible ones. Given that you don not plan  to spend too much money on the project, just use the best you can find to match the rims and the frame/fork.

I do not think that it makes any difference as of which rotors to use, as even the cheapest ones stop things as efficiently as the fanciest ones, while being only heavier.

For brakes, it depends on the terrain where you would ride this. If the area is mostly flat, I would say any decent modern disk calipers would do the job. If there are prolonged descents, then you'll have to look for four piston downhill-rated options for front wheel. With 203 mm rotors, look after the compatibility — most likely you will have to use adaptors from 160/180mm to 203mm.