Trimming a threadless steer tube with a tall-stack stem?
 

I'm setting up to assemble my wife's new bike, a steel Georgena Terry frame/fork built by Waterford. The question has to do with the allowable length of the steer tube above the headset. How long do I leave it if I use a tall-sleeve stem, like the Velo-Orange "Tall-Stack" stem? It has a longer sleeve around the steer tube, length is 75 mm. For a normal stem, it's more like 40 mm for a Velo-Orange, or 36 mm for a Thomson Elite X2.

Waterford advocates no more than 40mm of spacer between the stem and the headset. I assume this 40 mm includes a brake housing stop for the front brake (we will use canti brakes). For a standard stem, that means the steer tube should show 76 mm (if I use a Thomson stem), or 80 mm (if I use a standard Velo-Orange). But if I use a Tall-stack stem with a stack height of 75 mm, could I make the steer tube 115 mm long above the headset? Will this cause any problems?

i would assemble it without cutting off anything and then determine how much i needed to cut off.

Ok, but doesn't it matter that the steer tube not be left too long, with too much length of spacer?

Well, it's about how much leverage there is on the steerer... so, given it's for your wife, and any general dimension recommendations are gonna be made with a big guy in mind as the worst-case scenario, I'm sure you can stretch it, maybe 50% even, given how much less grunt is likely involved in this case.

Throw it together how you'd like to build it, and get the wife to put some torque through the bars and observe.

So you think the main concern is in flexing the steer tube based on rider weight and strength? That makes sense, actually.

Yeah, it's really no biggie IMO.

steel steerer? what riding posture is desired?

Note: Threadless setups work fine with spacers over the stem or under it . shuffle them to test and ride for awhile before cutting the fork, any. .

This is a steel steerer tube? Never heard of spacer restrictions on a steel steerer. Spacers above the stem should be immaterial as long as you can get the top cap bolt in the star nut. I'd go with a lot until you have dialed in the bike fit, then recut the steerer with a small spacer above the stem.