You can easily fill any wood cracks with glue and a clamp. Here is how:

Using white wood glue, lay a bit at the crack and use your finger to push the glue into the crack, adding more glue until the crack is filled.
Clamp on either side of the wood where the crack is
Glue will come out after you set the clamp - this is normal
Wipe with a damp clean cloth and set for 12 hours

The glue is stronger than the wood, so repairing a crack with glue makes that area the strongest point in the wood - which may prevent future cracking as well.

It is good once a year to thoroughly look over your wheel to make sure you don't see any hairline cracks and to fill those with glue.

SpinOlution Wheels are Finished in Clear Lacquer. To clean, use furniture polish.