Custom 650B frameset. Looking for geometry input

Discuss light weight issues concerning mountain bikes & parts.

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by lancejohnson

I'm having a friend build me a custom 650B mtb. It's my first mtb (well, since the old Tange steel Breezer with XT that I picked up as a townie for $50 and desperately wish I had still), and while I am usually able to give detailed input on geometry, I don't know much of anything about mountain bikes. I want it to be precise and agile, but also, as forgiving as possible since I will be working on building my skills up from a very low level. I want something that will be fun to ride now, and that I can keep for a long time without feeling like I've outgrown it, or the geometry is holding me back. I'm hoping to love mountain biking and maybe add one of those sweet all-Ti Erikson FS 650B's that Kent showed at NAHBS if I do.

Bike will be used for marathon-style and x-terra-type riding. I won't be (primarily) doing XC or short-track racing, but might try it from time to time just for grins since I live in Boulder and we have enough races around here to hit one up any time you want.

I can tell you all about my road bike (which fits like a glove), 73.5 STA (Rotor 0-offset post and saddle dead center on the rails), 72.5HTA, 52cm c-c seat tube (eff), 54.5 c-c top tube (eff), 75mm bb drop, 40.2 chain stays (very stable, but I can rail corners and flick it around potholes as well). I have a saddle height of 70.3cm, a 100mm stem, and a drop from the top of the saddle to the top of the bars of 78mm. I spend most of my time on the hoods, but can tuck to the drops when hammering or on a long descent. I'm 175cm and predominantly torso, but don't have particularly long arms.

I know that a great bike builder should be able to help me decide this all, but I also like to go in armed with lots of good information so that I can be an active participant in the process.

Thanks for any help. I appreciate it greatly.

"Organization is for the simple-minded, the Genius controls the chaos." - Jens

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by HillRPete

Try all MTBs you can get hold of, and record their geometry. Find out what works for you and what you like. Only then talk to a builder about angles and lengths.

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