Geometry and fit for the frame builder

[seankanary]

Good morning guys, I was wondering if you could shed some light or at least point me in the right direction for reading material. I'm trying to wrap my head around how frame builders arrive to the geometry they use for a customer. When I follow links to most of your websites, you all seem to have a form asking the customer to provide you with their basic body measurements as well as their current bike setup. My goal here is to build a bike for my brother (birthday is coming up), but I'd like to know how to measure him correctly. Here is an example where I'm a bit confused:

My friend and I are the same height, he has slightly longer legs...around 1.5" taller inseam. He has always ridden 58's, I typically ride 56's. When I hop on his bike, it is freaking HUGE on me and on my bike very small on him. When I compare some of the geometries of his bike versus mine, there is almost no difference.

I guess my question is, what is your process and what considerations do you keep in mind for sizing a frame to a customer? I'm interested to see how alike or different everyone's process is. Thanks!

[e-RICHIE]

Good morning guys, I was wondering if you could shed some light or at least point me in the right direction for reading material. I'm trying to wrap my head around how frame builders arrive to the geometry they use for a customer. When I follow links to most of your websites, you all seem to have a form asking the customer to provide you with their basic body measurements as well as their current bike setup. My goal here is to build a bike for my brother (birthday is coming up), but I'd like to know how to measure him correctly. Here is an example where I'm a bit confused:

My friend and I are the same height, he has slightly longer legs...around 1.5" taller inseam. He has always ridden 58's, I typically ride 56's. When I hop on his bike, it is freaking HUGE on me and on my bike very small on him. When I compare some of the geometries of his bike versus mine, there is almost no difference.

Measure your foot length. Your leg length (NOT your inseam) plus your foot length drive the saddle height measurement atmo.

[JimFrain]

You could check out the bike website as well its a good start.

The Bicycle Forest :: BikeCAD

They have a simple version of their pro software available on their website. Also their FAQs have some information about measuring people to fit properly on their bikes.

The paterek manual. Is a great read.

Richard just posted a very interested thread about fitting last week.
http://www.velocipedesalon.com/forum...ess-32712.html

Also, like most things related to frame building this takes alot alot (< 2 alots on purpose) of experience. Both with bikes in general and people on them. I would definitely like to see some long term threads about what type of geometry and fitting folks do as well. Many aspects can be very subtle.

Going to manufacturer websites and seeing what they use for basic geometry can be a helpful gauge to see if your on the right track.

Good luck with your bike!