City bikes-- frame sizing for smaller cyclists I'm a 5'1" woman looking to purchase a classic bike for transport/leisure. Unfortunately here in the London and in neighbouring cities/countries, I can only find 17"+ frames available. Most sizing charts recommend 15" for me.

Perhaps I have more flexibility given that I'm not properly sizing for a road/mountain bike or anything. Would a 17" frame be ok? I don't want to strain my knees or risk back issues.

Total novice at this, but I also measured my inseam in two different ways. 28.5" maximum if I want 1 inch of room while standing over the seat. 23" if I use the book method and allow 5 inches of room while standing over the seat. Seems like a lot of 17" bikes online lower down to 26" inseam height.

Many thanks!
I helped a friend having a similar issue long time ago (she was 154cm ... I think it is similar height to yours, right?).

What we found was that a 17" frame would be okayish regarding leg's length, but a bit of a stretch regarding the torso/back, because the handlebar was too much forward.
However, for cycling stretches of 20-30 minutes this may be ok and you may still have a relatively simple albeit unconventional solution: reverting the stem (the metal piece used to attach the handlebar to the fork) to point backwards  

In our case, the solution was to buy a 26" bicycle. 
Sometimes these bicycles are advertised as "young adults bike" but they are completely adequate for your declared purposes.