What Bike Size?
Discussion
The thread about Rejecting a Bike, as well as a recent trip to Halfords got me thinking.
How does one know what is the right size frame for you?
I am a short arse so am 5ft 8 but my inside leg is only 29inch. Now according to the Halfords website for a 29 inch inside leg I need a 16" frame. However use my height of 5' 8" I should be on an 18" frame.
Further investigation shows that my current bike appears to be a 22" frame.
So what determines the size of frame you need, what should ones posture on a bike be? I assume its different between a road racer, and a mountain bike and possibly a hybrid but could be mistaken.
Where should the handlebars be in relation to the seat etc?
How does one know what is the right size frame for you?
I am a short arse so am 5ft 8 but my inside leg is only 29inch. Now according to the Halfords website for a 29 inch inside leg I need a 16" frame. However use my height of 5' 8" I should be on an 18" frame.
Further investigation shows that my current bike appears to be a 22" frame.
So what determines the size of frame you need, what should ones posture on a bike be? I assume its different between a road racer, and a mountain bike and possibly a hybrid but could be mistaken.
Where should the handlebars be in relation to the seat etc?
My scientific way of dealing with this is to go and ride the bikes. If it is comfortable then it's the right size. Using this amazing technique I have successfully purchased two very good bikes (one road, one mtb) which allow me to go on rides from 2 to 5 hours long with no discomfort.
I would never buy a bike without riding first. Asking for all sorts of trouble.
I would never buy a bike without riding first. Asking for all sorts of trouble.
There is bound to be some better explanation along any moment, but my full sus bike is a 16 inch, my hardtail was a 17 inch, and my road bike works out at 22 inches. I am also about 5ft 8 or 9 depending on the weather with similar length legs, but long arms, so the road bike had a longr stem fitted.
Hope some of that helps
Hope some of that helps
as well as seat tube length, top tube length makes a massive difference, this is relative to your upper body.
two people may be the same height but one may have much longer legs.
its always worth getting the top tube measurement of any bikes you are looking at buying for comparison. then road bikes have horizontal and sloping top tubes which thorw more issues into hte mix... and just to confuse matters more, road bikes are measured in cm and mountain bikes in inches...
two people may be the same height but one may have much longer legs.
its always worth getting the top tube measurement of any bikes you are looking at buying for comparison. then road bikes have horizontal and sloping top tubes which thorw more issues into hte mix... and just to confuse matters more, road bikes are measured in cm and mountain bikes in inches...
Try this guide
http://www.google.co.uk/imgres?imgurl=http://www.r...
I did have a better one but I cant find it at the mo.
http://www.google.co.uk/imgres?imgurl=http://www.r...
I did have a better one but I cant find it at the mo.
Seat tube length is becoming almost irrelevant as more MTBs move towards bent or sloping top-tubes - standover clearance should be guaranteed even on the bigger sizes.
As said above, Top-tube length is the measurement to concentrate on, when comparing sizes of a bike, or comparing different manufacturers' bikes. Once in the right ball-park, you can fit a longer or shorter stem to tune the riding position.
Another question, is how you personally will use the bike. Downhill or long days on fire-roads ? I would suggest a rule of thumb, that if you are spending more time standing up on the pegs, you could benefit from a smaller frame size. If you are sitting down most of the time, then you might be better looking for the ideal seat-bar position which could mean a larger frame.
Another reason why trying various bikes is important.
As said above, Top-tube length is the measurement to concentrate on, when comparing sizes of a bike, or comparing different manufacturers' bikes. Once in the right ball-park, you can fit a longer or shorter stem to tune the riding position.
Another question, is how you personally will use the bike. Downhill or long days on fire-roads ? I would suggest a rule of thumb, that if you are spending more time standing up on the pegs, you could benefit from a smaller frame size. If you are sitting down most of the time, then you might be better looking for the ideal seat-bar position which could mean a larger frame.
Another reason why trying various bikes is important.
Chrisgr31 said:
I am a short arse so am 5ft 8 but my inside leg is only 29inch. Now according to the Halfords website for a 29 inch inside leg I need a 16" frame.
Same measurements as me and I currently ride a 17.5" frame, although I have ridden 17", 18" and indeed 19" bikes for years
Frame size is largely irrelevant - as long as your feet, arse and hands are the right distance apart, the length of seat tube (standard frame measurement) doesn't matter.
MTB geometry has moved more towards smaller, compact frames which are longer in the top tube - hence over the years my frames have gone from 21", to 19", to 18" to my current 17.5". Road frames have been going along the same lines too. Lots of manufacturers have started going with S/M/L sizing to avoid any assumptions about specific sizes being right for a particular person based on height on inside leg.
MTB geometry has moved more towards smaller, compact frames which are longer in the top tube - hence over the years my frames have gone from 21", to 19", to 18" to my current 17.5". Road frames have been going along the same lines too. Lots of manufacturers have started going with S/M/L sizing to avoid any assumptions about specific sizes being right for a particular person based on height on inside leg.
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