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aprhockey 11-27-11 01:17 PM

Learning about frame geometry
 
Not sure if this is the right place to post this but I figured you guys would be the most likely to know. Are there any good sources that describe the various angles and lengths of a frame and how each affects the handling of the bike. I know the basics like a longer wheel base is more stable. Is there a good source that puts everything together? I've found a lot of random bits of information on the web but nothing that's really comprehensive.

Along the same lines, is there any book or website or anything that describes the differences in geometry of various bikes, like road vs. cyclocross vs. track vs. etc.

jimn 11-28-11 04:40 PM

I'd start by looking at the geometries of bikes on various manufacturer's web sites. Surly, for example, lists the geometries of all of their bikes. Sheldon Brown has scanned old Bridgestone catalogs where you can see what Grant Peterson was up to with road, mountain, and hybrid geometries. Then think about the bike or bikes that you own, and maybe try to ride some with different geometries. It will all start coming together, but it's a huge and contentious subject and there is no one place to find the right answer. Beware of anyone claiming to know anything about the subject, and let the existing bikes and numbers speak for themselves.

rodar y rodar 11-28-11 06:55 PM

It`s a pretty murky subject for me, too. Feel free to shoot me down, but I think an awful lot of it is guesses until the specific combination you`re considering has actually been built and tested. Aside from manufacturers` websites and catalogues, here`s a big collection of geometry data:
http://hiddenfortress.org/geometry/index.html

Cassave 11-29-11 11:52 AM

Dave Moulton's blog has some very good stuff.

http://davesbikeblog.squarespace.com/

aprhockey 11-29-11 09:39 PM

Thanks Cassave. He's got a lot of good stuff. I guess it's true what jimn said... there's info spread all over the place and no clean way to put it all together. Hopefully within the next few years I'll build/ride more bikes of varying geometry to figure out my own sweet spot.

jimn 11-30-11 01:54 PM

My best learning experience in this area was building a few bikes. Especially the bad ones - nothing will remind you of what a too-low bottom bracket or too-shallow seat tube angle means like riding it every day for months.

Road Fan 12-04-11 04:38 PM

Quote:

Originally Posted by rodar y rodar (Post 13541715)
It`s a pretty murky subject for me, too. Feel free to shoot me down, but I think an awful lot of it is guesses until the specific combination you`re considering has actually been built and tested. Aside from manufacturers` websites and catalogues, here`s a big collection of geometry data:
http://hiddenfortress.org/geometry/index.html

I'm not so sure everything is unknown and it all needs to be tested empirically. There are some configurations that have been in use for quite a while, such as the 73/73 degree angles combined with a 7 to 7.5cm drop and 42 to 44 cm chainstays. Racing, sport-tour, and distance bikes have all used something quite like this, dating at least back the the PX-10s of the mid and late '60s, into the Trek steel bikes of the late '70 through the mid-'80s. Today I see it on the Toei randonneur reviewed in BQ perhaps 18 months ago, and the current Boxdog Pelican.

Some good configurations are known and have been proven in the marketplace, as well as on the open road.

crnlmushroom 12-06-11 10:22 PM

What really helped me learn this stuff in the begining was a book at barnes and noble called a Lugged frame construction a manual for the first time builder by Mark Chimonas, it goes pretty in depth as to how each tube and angle effects the characteristics as well as how to actually find all those numbers

aprhockey 12-07-11 05:50 PM

Well, there's one christmas present for myself. I've been considering buying the Paterek Manual since I've heard good things. Does it describe geometry at all?


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