I need a help with choosing a wheelset for my Miele bike.I can't fully understand if it is possible to replace my old rigida 27 inch wheels for 700c coz i have too little free place.I visited a site where there is a size table of wheels and saw that it is possible(judging by numbers).There are no 27 inch wheels in my country at all,so im made to think of whether to put 26" or if possible 700c.
There a lot of charts posted on the internet explaining the complex data of bicycle wheel sizing. In your case you likely have standard 27 inch wheels that equate to a 630mm iso wheel. A 700c wheel is iso size 622mm, slightly shorter than your current wheel. The primary concern is if your brake pads can move close enough toward the axle to contact the brake surface of the wheel. Then you need to match the axle mounting type, basically bolt-on or quick release. Then comes hub width. Ideally you would like to match your old one however there are articles about drop out spreading on steel framed bikes. Definitely not recommended for aluminum or carbon frames.