oh God, I could spend that in a heartbeat, and I bet your friend can too. Cycling clothes, accessories, nutrition, shoes, maintenance/repairs/upgrades on a current bike, tools, etc. If cycling his HIS THING, I would not break it up unless there's a specific other store you think he'd really enjoy.
If it's an actual gift cert rather than a gift card with a balance that can be debited, I would break it up into several smaller gift certs though, so he doesn't have to use it all at the same time.
Wow, $2000! As of today, I could easily spend that in my shop. But, if I had the upgrades that I'd like already, then it might be better spent in other places.