Sit on the saddle of the bicycle you are interested in buying. Place your hands on the handlebar. Do you feel that you are leaning way too forward? If it is and you still like the bike, you can request the bicycle shop to change a stem with a shorter reach or replace it with one which is adjustable so that you can raise the handlebar nearer to you.
As you sit on the saddle, are your feet sitting flat on the floor? Raise the seatpost up so that only the tips of your shoes are touching the floor. Sometimes, you may have to change the seatpost if you can’t push the seatpost down any lower as the bolts installed for the cage could be blocking the way. To resolve that, you can change seatpost to one that is shorter in length or have it cut shorter by the shop.
Now get off the saddle and straddle over the toptube. Is your crotch area touching it? If it is, ask the shop to let you try one with a smaller frame size. So, if a 16″ to 17″ frame size (M size) is too high for you, you may have to try a frame size of 15″ (S size). Anything above 18″ is L size. The size is usually printed on the frame where the seatpost is inserted, just below the toptube.
It is safer to buy the bicycle if your crotch area is about 2–3 inches away from the toptube as you straddle over it. That way, should you have an accident and fall, you will not be hurt by the toptube.
