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Frame geometry(5 posts)

Frame geometryGuidosan
Jan 29, 2002 9:14 AM
I was wondering how frame geometry affects performance and comfort of the bike.
Just curious on what to look at for, attacking hills, speed, comfort and cornering. My interest is to get in shape for doing some centuries and other long rides. Any good guidelines that I can consider? Also, how much variation in frame geometry is there on stock bikes in the LBS, or should I start to look at some custom frames?
Thanks
Frame geometry affects everythig...PdxMark
Jan 29, 2002 10:14 AM
Geometry translates to how a bike fits you. A poor fit makes for miserable riding. Seat tube and top tube dimensions matter most for fit, I think. So, geometry greatly affects comfort.

Geometry greatly affects performance, too. But the nuances of seat tube angle, head tube angle, chain stay length, etc. can often be lumped into the performance reputation of a bike...

Finally, there is huge variation in stock bike frame geometry - huge variation meaning that just a cm here or there can greatly affect fit and performance...

Getting a fitting by an experienced, professional bike fitter can REALLY help you sort through all this.. It can be the best $100-$150 you spend on getting a new bike
Frame geometry affects everythig...DINOSAUR
Jan 29, 2002 10:59 AM
Good answer....I read a post on the VeloNews tech talk forum last year by a frame builder that basically said that he got tired of reading all the debates about frame material and the most important part of your bike selection should be geometry. It's the most over looked fact. Fit and geometry is the paramount feature of selecting a frame. The problem is when you first start out you really don't know what you like or dislike so just make sure your bike is properly fitted and find out what you don't like about your current ride and go from there.

I read an article by Sheldon Brown about geometry vs. frame material. I searched his site and couldn't find it. Anyone know what I am talking about? He said in essence, frame material doens't matter..it's all about how it's tweaked...
Frame geometry affects everythig...josh_putnam
Jan 30, 2002 12:21 AM
[QUOTE]
I read an article by Sheldon Brown about geometry vs. frame material. I searched his site and couldn't find it. Anyone know what I am talking about? He said in essence, frame material doens't matter..it's all about how it's tweaked...
[/QUOTE]

Perhaps it was one of his magazine articles, not something on his site?

In any case, he's quite correct. I admin the international framebuilders mailing list, and while all sorts of people have all sorts of preferences about choice of materials and joining methods, every competent builder I know agrees that frame geometry is far more important than the choice of materials.

I would lump the geometry question into two broad categories, rider fit and bicycle handling. Rider fit determines whether you'll be comfortable on the bike. Bicycle handling determines how repsonsive or stable the steering is, how the bike feels in corners and on rough roads, how well weight is distributed, what sorts of racks, fenders, panniers, shoes, and so on you can use.
Here is the article....DINOSAUR
Jan 30, 2002 10:57 AM
http://www.sheldonbrown.com/frame-materials.html