Here is a nice pdf I found on RCG. Read the pdf you should get it then.

http://www.rcgroups.com/forums/showpost.php?p=11707792&postcount=3

If you prefer buying then get these, cheap and durable.

Hey SunLikeStar

Have you used these gears? if so then can you explain more how you  have attached wheel to gears?
I guess you have use extra shaft and collar with these kind of landing gears.

No, I've not used them. But i've seen people at our field use these with m3 nut bolts for attaching wheels. Mohan at our field uses this landing gear on his spads and it works real good.

Thanks a lot for your advise. i will buy those