Regular visitor to Beijing, but I tend to stay in Chaoyang or the Financial Street areas. There is an excellent pool at the Kerry Centre in Chaoyang (non-standard distance - 35m) and a pretty average pool at the Westin apartment complex in Financial Street (Xicheng District).

On the west side of the city, I can think only of the pool at the Friendship Hotel - essentially an empty 50m pool, but more difficult to recommend.

Hopefully others will be able to provide better assistance.

The Universities around Wudaokou have Olympic size pools. I joined one as a member for their whole gym (the foreign language university), but the others all required knowing someone to join. You won't be able to get into these without speaking Chinese or translation help.

A lot of the gyms have short course pools hidden in them so just check the local magazines like thebeijinger. After moving central, I swam in a small but normally empty poll in Dongzhimen

I used to stay at the Park Plaza in the Beijing Science Park (I think Haidan district). Next door to the hotel there was an office/apartment complex with an 11th floor 25m pool. Most of the time it was empty. I used to pay RMB 50 to swim there. I also swam at the warm up pool at the Watercube a few times, but the actual Olympic pool was not accessible each time I visited.

Dev