I am fixing up a bike. The bike is a 3 speed hurcules all i have is the frame. I have a few 3 speed hubs shimino and maybe a sturmey. How small can i make the front ring? I want the bike easer to pedal hills. I have a bunch old front crank sets fron 10 speeds to use. Is the chain the same i have no chain yet?

Generally,you want to go with a front/rear ratio of 2:1 or greater, meaning if the sprocket out back is a 20t, you'll want at least a 40t chainring. This is true for 3 speeds, the majority of which have the direct ratio on the 2nd gear. Some IGHs have the direct ratio as the lowest (first) gear, and these can run much smaller ratios. (The flipside is, you basically have to run a smaller direct ratio if the direct is the lowest gearing offered.)

Hope this helps. If yours is a raleigh-built hercules, be aware that none of the threads for the bb shell or fork will be the standards you may be used to. Also, the fork might be spaced oddly, for a very narrow (91mm) hub with a scrawny (5/16") axle.

Good luck with the build!

Generally, 3 speed hubs will be geared-
3:4
1:1
4:3

I'm not knowledgeable about IG's, but I think they use 1/8"chain vs 3/32"chain for DER bikes.

Another caveat is strength.
Too low of a gear and the hub may not be strong enough if you are one to stand on the pedals. Especially if you have some old Shimano 333's.

Chain rings for 1/8" chain are OK since 3 speed hub cogs are rarely any thinner than that

BMX chain ... want nice stuff, track/fixie uses 1/8" chains & Chainrings too

You can run 1/8" chain, regardless. You can run 3/32" chain if you have a 3/32" chainwheel and you get yourself a 3/32" cog for your IGH (yes, they do sell them.)

To reiterate my above post, avoid anything less than a 2:1 chainring:cog ratio, and you won't blow your hub up.

thanks good explanation.. bottom bracket seemed normal i put a shimono sealed bottom bracket in it. thanks building the wheel this week end if i dont have to cut the spokes i am so tired of getting it wrong