Cindy, I had a huge ganglion cyst on the top side of my wrist removed in my teens. Went straight to surgery without trying aspiration. Honestly, if I had to do it over again, I probably would avoid the surgery and pursued frequent aspiration...not because of the surgery, but I think it took 2 years before I had complete mobility again (mine was right where the hand meets the wrist.

But to your question: can cycling cause this? To my understanding, "yes" it could contribute. Mine erupted following a bad bout of bersitis following a bad fall (kid stuff). I understand that a restriction on the internal flow of fluids contributes to the creation of this type of cyst.

Based on this, I agree with tulip that it might be as simple as "loosening up" on the grip or frequently stretching out your fingers during a ride. I also wear heavily padded gloves because of nerve issues.

I'm not a medical professional...this is just my humble opinion based on my experience.

Silver's had one on the bottom of her wrist aspirated many times...I think it finally went away...silver?