Dear all,

I'm new here and want to start off getting a bike.
My question will be

I'm abt 5'7"1/2 (171cm) tall and my legs height is 31" (79cm).
I'm choosing between these 2 frame height with the 440mm and 550mm frame.

Could anyone advice which frame will be suitable for me???
As this is my first time getting a bike.

I'm getting a cross bike aka hybrid bike for my first bike.
As I'm getting this bike on line a may not able to test it.

Thank u so much for your advice.

Duckie....

55 cm frames are small(-er). 44 cm I really cant see. If you´re 171 cm tall 55 cm should be OK.

I'm exactly the same size as you and I ride a 52cm Felt Hybrid. It is perfect for me. they do a 55, it would be too big for me, without doubt.

This said, different manufacturers are different so bear that in mind. I also have a hardtail MTB, a Be-One which I got smaller (so the wife can ride it basically too - she rides it with the seat fully down but it is still a good clearance from the frame top tube) but it does fit me ok albeit with the seat very high off the frame (but normal in many people's eyes). It is 16inch (41cm), if my wife was never going to ride it, then I would have got it slightly larger, woulvenave got the 18" (46cm) but defo not 52 like the felt.

I'll take a photo of both tomorrow and post.

I think 55 will be too big for you on a hybrid. I think you should be in between the two really, but it would depend on the bike in question.

So, here are my bikes... First my MTB, in my wife´s position, then in my position. My wife´s position on the bike is realistically too low for her, but she likes it low and it is totally just pottering along with the kids who are only 4 and 5.

I have my position on the MTB almost identical to my Felt Hybrid position, just slightly lower on the seat (ie- seat level to pedals - but only lower by 5mm or so). But you can clearly see how much smaller the MTB frame is to the Hybrid - The hybrid only has a small portion of the seat post showing whilst the MTB has a lot - It´s also a fact that even in my position on the MTB it is not at full height, it could be put up 40mm more to be at the capacity maximum which would totally be far too high for me and my inseam.

I think the fit on both bikes is perfect for me, although in truth I would go to an 18" (460mm) on the MTB if my wife wouldn´t ride it, but having a smaller frame on the MTB makes for easier off roading for me, much easier to chuck around. The 52cm Felt is 100% the correct size for me, 55cm too big and I am 100% sure it would be for you too, you would need the same as me or the slightly smaller 48cm. But this is all based on Felt Hybrid Geometry, others will be slightly different.

Cheers.

Wife´s relaxed position.


My MTB position.



My Hybrid position.


So, you can clearly see that although the seat position is (roughly) the same, the MTB frame is much smaller but does the same fit job.

Just did a comparison photo overlaying the bikes....

Buying mail order when you don't know your size is always a risk. If you can get to a local bike shop, then that's what you should do.
The critical dimension for fitting is length rather than height. The ratio of length/height varies so you cant always tell. It can vary between different sizes of the same model (ie smaller bikes are proportionately longer). It also varies between brands.
Generally within a brand, most bikes of the same style/size share the same geometry.

Length consists of 3 elements.
-Frame length from seatpost to headtube (in a man's bike, the top tube or where the TT is slanted, the virtual TT)
-Seatpost layback. Seatposts connect to the saddle using a clamp. This may be inline with the post or may be set back a few cm, pushing the rider back over the pedals. You can switch them to adjust the saddle position beyond the adjustment rails.
- Stem length. Most bikes come with a stem which is appropriate for the frame size but you can change it for a longer or shorter one to fit your reach. Some bikes come with an adjustable stem.

The "correct" length is entirely personal, there is no formula. As a new rider, you will probably prefer a short reach but with time, your position will generally get longer.