Hello. I am about the purchase an IRO Mark V SS and they ask you to choose between a 100mm stem and a 110mm stem. My arm length is about 29 inches to my fingertips. Would I rather have the stem a little longer (110mm) or a little shorter (100mm)?

Do you have a bike that fits you well now that you can measure? Measure from the center of the seatpost to the center of the handlebars. Subtract the top tube length of the IRO you are considering and see if it's closer to 100 or 110. There really isn't that much difference though so either way you should be fine.

your arm length matters just as much as your shoulder position and your torso length as well as the size of your frame.

fit isn't an exact science without all the measurements and even if it was you didn't give us the ones we'd need to make the data you did provide relevant.

get two stems, and try them each out. or get fitted at a bike shop that has a fit bike, or at least demo fit stems.

i think we should initiate a policy- no answers to fit questions.

'it doesn't matter' is also not an answer... there will be a difference though it will probably just be the angle your butt's on the saddle and the angle your backbone bends.

https://www.competitivecyclist.com/za...LCULATOR_INTRO

fit calculator

I second no answers to fit questions. There are too many variables and not know if the person asking the question took the right measurements and what not.

Fit is something you should have hands on. Go to a bike shop and let them fit you to the bike, yes it will cost you money but you will be much more happy with the end result than you would by taking our advice. We are not standing in front of you and seeing how your body fits on the bike.

There is to much room for miscommunication on here.