I think I'm settled on going with a nitto technomic. My question is whether I should get the long or short version. Both can be seen here https://www.benscycle.net/index.php?m...8_263_1332_712.

Am I understanding this correctly? This is info from the short stem: "Quill length is 75mm from minimum insertion to center of extension." This means that the tallest this stem can go from the frame of the bike is 75mm, but it can go lower if desired?

If I am correct above, then according to the info on the long stems, "Total overall length of the quill is 225mm. 160mm from minimum insertion mark to extension," they can go up to 160mm tall, but can be lowered as well. Does this mean that the long one could actually be lowered to just as short as the short? If this is the case, then I feel like a long stem is better so that there is more play in adjusting it to how it is comfortable. Am I way off here?

the stem can only go as low as the steerer tube on your fork.
generally taller bikes have more adjustment room because the headtube and steerer tube are longer.

The stem will be on a 57cm kilo tt. I'm 6'1" and my main concern is that the short stem which maxes out at 75mm may be too short. I've never used a quill before and read that there is no way to be sure of what your exact size will be. Thats why I figured the longer would be a better first guess?

in your case, go with the longer. you can always make it go lower by inserting it further.

thanks. The stock kilo stem seems like it measures to about 110mm so I think ima go with the long version in 110mm.

Is the stock Kilo stem quill? Do you have a threaded headset and fork?

1) 110mm threadless does not equal 110mm quill. The quill will have to be longer to account for the angle. Use this website to figure out the math: https://alex.phred.org/stemchart/Default.aspx

2) Why devolve your bike to a quill stem?

In the event the long quill is too long and you can't get it any lower in the head tube you can cut the quill shorter. I've done this with my Nitto stem. It's not an easy job, but certainly doable with the right tools.