1. You may get a bargain
1. You may end up over-paying
2. The bike might be stolen
3. The bike might have been part of a false insurance claim
4. The bike might be damaged
5. The mechanical parts could be worn, (many bikes are sold with the chain and cassette near the end of reasonable life)
6. Recourse is difficult and arduous if any of points 2 to 5 are true.
7. Organising a convenient time to take delivery of the bike can be a challenge if you're not at home all day..
8. Shipping is costly
9. If shipping is not costly its possible the bike isn't adequately insured during shipping.
10. The bike could be damaged in transit.
11. You struggle to see the bike in the photo as it blends into the sofa/bed/armchair/garden fence it's leaning against
12. The details are not detailed enough
13. Your questions are either answered vaguely, not at all, or just after the auction finishes
14. The bike you've finally had your questions answered on finishes early
15. You have your questions answered, it doesn't finish early, but you get outbid in the last minute
16. You have your questions answered, it doesn't finish early, you don't get outbid, but the seller decides not to sell in the end
London Cycle Exchange There is a better way - Used Approved Performance Bikes