|
|
| *Vultures Knob>>>Cycling |
How is the framesize of a bike measured? |
I am going to buy a new bicycle and I'm just really curious how all the different frame sizes are measured? I see frames from 59 cm up to 62 centimer... What excactly makes them (the frames) so different? those measurements are made from the center of the bottom bracket (the center of the crank arm) to either the middle or top of the seat tube (the tube where the seatpost goes in). since wheels are pretty standard, a bike's size depends on the frame more than anything, and you should see more than 59-62, most frames start at 48 and go up. it takes someone pretty tall to ride a 59+ frame. i am 6'2" and ride a 58. a bike shop can help you decide what size you should be looking for. to make it even more confusing, some list thier sizes in inches. you really need to go stand over a few to know what size you need. a general rule is that standing flat footed over the bike there should be a couple inches of clearence between your crotch and the top tube, but that is general because compact frames have sloping tubes and are different. The measurement of a bike's frame size is the length of the vertical bar under the seat (if you look at the bike's frame as a triangle, it's the piece of the triangle that goes straight up and down). The frames are different in order to accomodate people of different height. Generally the taller you are the larger of a frame size you need, although what frame size you need may be smaller or larger than the average frame size for your height if you have particularly short or long legs. When a bike is correctly sized, you should be able to have your leg have a very slight bend in it when you are at the bottom of your pedalstroke, with your foot parallel to the floor. WHOOA !!!!! Not all frames are measured from bottom bracket to seatpost. Some bikes are measured from the center of the headset in a horizontal line to the centre of the seat post. BE WARNED! Some cheaper bikes use an inside leg measurement too??? If you are thinking of spending a lot of money for a bike then go to the bike shop and get measured up. Hope this helps. Acadia - Far be it for me to question your experience, but the bent knee thing you describe, is to do with seat height, - NOT bike size. I stand by my answer and advise the asker to check with the manufacturer or retailer on their method of measurement.(Argos for example use inside leg) M R welcome to the world of bikes, some 'modern' frames are of the compact design and if you stick by your method of measurement, Your new bike will be massively oversized. I've been around bikes all my life and I'm well over 40. I worked in bikes shops was a partner in one for a time and raced MTB and road too. I've never heard of a bike size being measured in any other way than from the center of the crank to top tube or seat tube with some minor variations. Frame size is never horizontal. The horizonal or effective top tube measurement is very important but it's never to be confused with what is universally known as bike size measurement. Look on ANY manufacture's web site many will have a graphic depicting exactly what I said. Because of my experience I know there are variations like measuring from crank center to bottom, center or top of top tube. The unexperienced wouldn't know this. I stand by this answer as hoizonal measurement is NEVER used as a bike size. The Best way to measure your bike or one that you want is to get one that you think might fit, stand over the top bar (straddle it) and be able to have about an inch or so between the middle of your legs and when you lift the bicycle up off of the floor before the cross bar touches your crotch area,,,, so this measurement is taken from the floor to the top bar,,,,, this is from Trek Dealers in all states, that is how they measure them What you really want to know is: how do I get a bike that fits? Manufacturers sizing may vary (similar to shoes). Shopping for shoes, one brand 10 may be the same as another's 9.5; in the same way one bike sized at 54cm may be another manufacturers 56cm. In addition, different geometries (the way the various tubes are joined together and fitted at different angles) likely impact the sizing. As mentioned, for "regular" road bikes where the "top tube" is parallel to the ground, make sure there is about an inch of clearance when you stand over the tube. For mountain bikes, and compact frame geometries (where the top tube slopes down between the headset and the seat tube), it's better to have more room for the technical aspects of going downhill on trails. Sometimes up to 4 or 5 inches is warranted, though the more seat post is exposed, the more likely you will replace the post. Nice chart for sizing: http://www.stationcycles.co.uk/sales/siz... Another simple sizing example: http://www.dynamicbicycles.com/bikes/siz... REI fitting guide: http://www.rei.com/shared/help/fit.jsp?s... Beam bikes -- how are they sized???-- http://www.ultracycling.com/equipment/be... |
| Tags |
| Cycling Bike Race Bike Insurance Bike Repair Bicycle Shop Bike Tours |
Bike Categories--Copyright/IP Policy--Contact Webmaster |