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Bike Frame Size


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Showing 1-13 of 13 posts in this discussion
Initial post: Apr 16, 2012 12:11:23 AM PDT
Jason says:
I don't know which frame size to buy since I'm new to cycling. I'm 5'6". What is preferred? 48cm, 57cm? A general idea would be fine since i'm not providing much measurement information.

Posted on Apr 16, 2012 2:59:42 AM PDT
parker says:
You need to give more info than just height, sorry. Inseam? Male or female? Handlebar to seat reach? Etc. Your best bet is to go to a local bike shop to get measured. Or, at least sit on a few bikes to see which frame size and geometry fits you best. Buying a bike without knowing your true measurements is a surefire way to have a terrible start to cycling.

Posted on Apr 16, 2012 9:12:19 AM PDT
Jamie says:
I would guess 51cm for a road bike or 16" for a mountain bike. If you have average body proportions (inseam, torso, arm length) this should be fairly accurate, but you really should go to a bike shop and sit on some bikes to be sure.

In reply to an earlier post on Apr 16, 2012 6:18:52 PM PDT
TJL says:
Try competitivecyclist.com. They have a fit calculator which should get you in the ballpark.

Posted on Apr 18, 2012 3:11:41 PM PDT
B. Kaufman says:
Pay attention to FIT, it can make you a very efficient "engine" for your bike or make you miserable in all sorts of ways. I am rather tall, with fairly short legs, (6', 30" inseam) so I ride a medium frame, where general suggestions all were for large, and I used a seatpost with an extra 1.5" rear offset, and a replacement set of bars to give me more "cockpit" room, and an upright riding position. Expect to find the seat too high, and the bars too low, at first, as well, until you get comfortable, and more riding experience.

If you fail to get the correct size, you may get muscle strains, repetitive stress injuries, and injuries of all sorts, that you may not even connect with riding a bicycle.

Posted on Apr 23, 2012 7:37:24 AM PDT
sst73 says:
As trent says the fit calculator is the best idea. I used it and ordered online with a perfect fit.

Posted on Apr 27, 2012 9:38:45 PM PDT
D. Spencer says:
I am 5'6" as well and about 150ish pounds. A 52cm bike is probably perfect for me. I rode a 50cm for a but and it was too small, and I currently have a 53cm which fits good but just a bit big. Hope that helps.

Posted on Apr 28, 2012 10:45:19 AM PDT
So I am reading all the comments about frame size. I went to the buyer's guide and measured my inseam, torso, arm length, but am still confused about size to buy. I am just shy of 5'10, 153 ibs, arm length 26 inches torso and 26 inches arm length. Can anyone suggest what size i would buy? Medium or Large? I'm interested in the hyrid women's road bike, which goes by small (13 inches and 15 inches), medium (17 inches), Large (19 inches). I have long arms and legs and a shorter torso. Thanks for your help on this if anyone can advise me. Hate going into shops. Would rather order on line.

Posted on Jun 3, 2012 8:08:17 AM PDT
Bob857 says:
Scarlett Fields - inseam is probably the most important measurement when choosing bicycle frame size, but given the bike sizes you've listed (small, medium and large) the medium is the likely to fit. I hate to say this, but... go to a local bike shop and ask to them to sell you a bike that fits you.

Posted on Jun 3, 2012 8:45:04 PM PDT
Vince says:
To the OP:

Inseam is not necessarily the best way to determine bike size. If you have short legs and and a long torso, you'll wind up with a bike too small. Why? Keep reading.

The key measurement when determining a bike is the head tube length. The headtube more or less determines the height of the handlebars. If the headtube is too small, the handlebars will be much lower than the saddle...resulting in an uncomfortable position.

No matter what bike you buy, the distance between the bottom bracket and the saddle will always have to be adjusted to same height to accomodate your legs. Once you determine the ideal height of your saddle, THEN you can determine the how high you'd like the handlebars to be...which equates to how much 'drop' you'd like from the saddle to the handlebars. Personally, I like zero 'drop'...meaning I like the bars and the saddle to be level with one another. For me this means getting a bike that has a relatively large headtube....which means buying a bike that is actually considered too big...but is NOT.

I'm 5'7" and ride a 57cm quite comfortably, The saddle is very low(only about an inch of seatpost showing) and is pushed forward to accomodate my short femurs...and gets me in the correct position over the pedals. The headtube is sized so that the saddle height and handlebars are level.

Bottom line, within reason you really can make any bike fit with some adjustments. However, if the bike is too small, the handlebars will be too low...and then there is nothing you can do about that.

For someone 5'6" I'd recommend a 55cm, though conventional wisdom would say 53.

Posted on Jun 5, 2012 7:47:52 AM PDT
Rob Winger says:
While most bikes are measured according to length of the seat tube, that really isn't the most important (or even accurate) measurement. Sizing isn't consistent among manufacturers (some don't account for the difference a sloping top tube makes to the effective size of a bike) and the height of saddle can be easily adjusted with the seatpost. The length of the top tube is probably the most important measurement, but even so, differences in frame geometry will effect both fit on handling. And of course what and how you ride comes into play, an upright city bike for cruising around is going to fit differently than a nimble racing bike where you are positioned leaning forward. For any bike, once you have a reasonably good fit with the frame, swapping the stem is a good (and inexpensive) way to dial in the perfect fit by get the bars at the perfect reach and height.

You really need to go to a bike shop and try out a few bikes. The sales people can help explain how a bike should fit and help you select what's best for your riding style. Most will assume you are going to visit a few shops to select the perfect bike, so even if you plan on buying used, this is a worthwhile step in the process.

I started riding a lot this year and had my road bike professionally fitted at a local bike shop by a trained expert. I ended up buying a new stem and handle bars and the combined cost of fitting and parts was < $200. My bike handles better, my speed increased slightly and I am MUCH more comfortable on long rides - some of the best money I have spent on cycling. Fit is extremely important when buying a bike and there is no substitute to riding it to determine if it is correct.

Posted on Jun 6, 2012 12:38:15 PM PDT
Bob857 says:
Sir Isaac Newton should not be offering advice on bike fit. Guaranteed his bike does not fit him, worse than that, it's dangerously oversized for him. Do not listen to him. A properly fitted bike would ride better. Stems are available with varying rises, as well as extensions, to fit almost everyone so they won't have to ride a bike that way too big or small. The best place to get advice on this is at a bike shop. If you go in looking to buy a comfort or hybrid and the staff wants to up-sell you to a $45 fitting, go someplace else. Fittings like those are only a benefit for hard core roadies. You need to be able to have an inch or two clearance when straddling the bike. From there it's easy to determine proper stem length and height and if you buying a new bike most shops will swap out the stem to one that fits for little or no money.

Posted on Jun 7, 2012 9:49:54 PM PDT
Vince says:
Bob857 is not someone you'd want to listen to. I've been riding bikes well over 40 years and have an arsenal of various sizes from 52 to 57cm...and they can all be made to fit the same in terms of the contact points (saddle, hands, feet). However, larger bikes are more comfortable when you're riding them, as opposed to merely straddling the top tube. If you have relatively short legs, then having two inches of clearance while straddling the top tube(as Bob857 suggests) may well put you on a bike sized for a toddler. And no, it will not fit you properly.

My earlier post wasn't meant as concrete advice..I was instead suggesting that there are different philosophies as to what a good fit really is. The idea of riding 'one size up' is known as the 'French Fit'...and is meant to be more comfortable since the headtube is larger. I should mention that this is probably more important with road/racing bikes. Comfort bikes and hybrids already have a large headtube to begin with.
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Discussion in:  Cycling forum
Participants:  11
Total posts:  13
Initial post:  Apr 16, 2012
Latest post:  Jun 7, 2012

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