Bike Frame Size Guide
Bike frame size is the single most important thing to get right when you buy a bike. You can change all the other components, but you are pretty much stuck with the bike frame size.
Bike frame sizes are based on the height of the bicycle, measuring the length of the seat post tube.
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Personally I have made the mistake of buying a bike that was too big, just because the price was right and I loved the bike.
Big mistake! I could never get completely comfortable on the bike, and eventually I had no choice but to sell it. I hate to admit that I actually made this mistake twice! (I’m just a sucker for a pretty bike.) It’s an expensive, time-wasting mistake – and it can even be dangerous.
If the bike you give has the right frame size, the lucky recipient will be able to comfortably stand over the cross bar. He or she will be able to stop safely, rather than having to fall helplessly sideways until their feet hit the ground.
If the bike is too small, the cyclist’s knees and back will probably start to hurt, and they won’t be able to use their leg power efficiently (plus they will look funny – a bit like a penguin!).
Height and Inseam Length – the Two Vital Measurements to determine the bike frame size
If you are planning to buy a bike gift for someone you love for Christmas, you will need the lucky person’s height AND their inseam length (the distance from their crotch to the end of their pant leg). Presumably if it’s someone you love, you can get those measurements without being arrested.
Of the two lengths (height and inseam), inseam is the most important.
The reason the inseam length is the most important is because it determines the person’s standover height. For example, if a bike has a standover height of 27 inches, and the cyclist has an inseam length of 29 inches, he or she will be able to stand over the bike, and the cross bar will not hurt his or her most delicate bits. (Obviously this is less important with step-through style bikes that do not have a cross bar.)
For road bikes the cyclist needs to have about 1 to 3 inches of distance between the bar and their crotch; for mountain bikes it is safer to have an inch or two more.
Two Different Bike Frame Size Systems
To make it a bit more complicated, there are different bike sizing systems. There’s one system for road bikes, and then a different one for mountain bikes and hybrid bikes. You can figure out your bike frame size with the Bike Frame Size Guides below.
Note that even with the right frame size – if the person is planning to do a lot of cycling, they should still get their bike fine-tuned with a professional bike fitting. This will ensure they don’t get back pain or cycling knee pain.
Adult Bike Frame Sizes
Kid’s Bike Frame Sizes
Good luck! I know your gift of a bike is going to make someone you love very happy.
Note: The tables showing how to pick the right frame size are extracted from my Bike Buyer’s Guide. Click the subscribe button below to get a free download of the entire book!
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