A set of 3d printable bike rollers I designed and made. Over 100 hours of printing and almost 2kg of plastic! Indoor training time! Check out the instructions for details.

http://youtu.be/nO8m7p93CHg

All the parts were printed in PLA on my Makerbot Replicator 2. I printed the center roller sections with 4 shells and 20% infill. The roller ends are 3 shells 10%infill. The bearing supports are 3 shells 10% infill also. The roller ends needed supports turned on (for the belt groove). The bearing supports needed a tiny bit of heat to let the bearings seat. All hole sizes are adjusted for correct sizing once sliced with MakerWare.

There are two center section options:
A: 3 piece centers, you will need 3 per roller (9 total).
B: single piece center, you will need 1 per roller ( 3 total).
Option A allows for stronger rollers and fewer print failures due to overly long prints. It also means a smaller piece to replace if you have a roller break.

I used a bit of glue between roller sections on the driven rollers.

After positioning the rollers on the side rails, measure your belt length with a fair bit of stretch. Fuse the ends together with heat (I used my soldering iron set to about 450˚ F). Trim the flashing then reinstall the belt

There are extra belt grooves in the rollers if you want to drive a resistance unit or other things.

36 x M3 x 10mm SHCS (mcmaster 91292A113)

6 x R8 bearings (mcmaster 60355K601)

3 x 1/2" x 16" Shafts (mcmaster 6061K432)

12 x Set screw shaft collars (mcmaster 9414T11)

aprox 8ft 3/16" urethane round belt (mcmaser 59725K703)

2 x 5' lengths 1/2" EMT conduit (sourced from Home Depot)