[Deyv]

I have a Zaskar 1998 and it's replacement is on the way (ok a long way it's expected in feb!) How do I measure my current bike to make some decision on stem lenght, etc.....

I know (think) that GT measure their bikes differently because my 16 fits like a 17.

Also how do I measure my stem lenght and rise?

sorry for the newbie question I just been riding for 10 years you know

 

[LostBoyScout]

I know it sounds crazy, but you can actually measure using a tape measure.

Effective top tube is what you want to know, which is a bit tougher to measure though. You can measure top tube by going from center of the seattube to center of the headtube along the top tube.

Effective is measured a couple ways, but I think you'll be good to go from center of the seattube right at the quickrelease, keep the tapemeasure as horizontal as possible and where it crosses the headtube centerline (might be down where the fork is - this is fine - just match it up with the centerline of the headtube

Then scope the effective top tube of the bike you want
To measure rise you're gonna need to whip out the geometry kit from highschool.

 

[oldfart]

Not quite boy scout. Effective top tube length is what you want to measure to get in the ball park. That's measured horizontally from the seat post center line to the head tube center line along a horizontal line that describes where a horizontal top tube would be if you had one. But you also have to know how tall the fork is and how tall the head tube is. If the fork and/or head tube are taller than what you have you will want to look at the rise of the stem too. Bottom bracket height is also important as that affects seat height and its relationship to the front of the bike.