What length riser stem do I need?

[sefton1275gt]

I usual ride a 54cm (effective top tube) with a 12cm regular stem (-6 maybe)?

I have a new (old) bike that has a 58 effective top tube.

However rid like to raise the bars about 4cm

What degree riser stem and how long should it be to achieve the 66cm length I like.

Also, it's a 1" fork steerer. I noticed there are many spacer kits to convert to a 1 1/8... Are these a reliable / durable solution?

Below is my stwm without the top cap

 

[bikeworkshop]

If you're happy on 54tt, it's unlikely you'll like 58. Even if you adjust the reach to be the same, the steering dynamics will be very different.
20mm is perhaps the limit.
Inch quill to 1&1/8,ahead adapters are heavy but effective.

An inch and an eighth stem will look awful on a narrow inch quill steerer tube though.

 

[sefton1275gt]

I plan to tour / bike pack on it so I wasn't overly concerned about the bigger frame size.

It's not currently a quill stem.

 

[bikeworkshop]

If you put your elbow pushing back on the nose of the saddle, you want the bars about an inch away from your fingertips.

 

[bikeworkshop]

The shims that fit ahead to ahead are absolutely fine.
Those steel univegas are really nice, an underrated classic, but prone to being a little long. The paint looks beautiful

 

[novocaine]

I'd slap an adjustable on there for a month, play around with it till it suits then bin (or sell, or donate to a worthy corse, or put it in the parts bin) it and buy the equivalent fixed stem. this obviously only gets you over the raise bit, but stem length I'd be looking at 90mm or the shortest adjustable you can get.

Mr Workshop above is really correct, but if it's a must, it's a must.

 

[sefton1275gt]

The adjustables might be a good call long therm.

Like a quill stem, they are nice to adjust mid tour (when your neck etc stars to ache)

 

[bikeworkshop]

You can swing these bars around, and as the hand position is back from the stem clamp, it suits a long frame:
Don't generally like them, because people think they are going to be comfortable on a good- fitting bike, but they might be just the job here.

Note the mirror.
Draw your own conclusions.

I've got half a dozen in the shop because we take them off bikes a lot more often than we fit them

 

[Tootyred]

Use this you can work it out. Take ypur existing frame and stem....put the measurements in, then play with the calculator till you get a length and height you need (or could achieve allowing for the bigger frame).

Its a useful tool as the reach and height of stems changes with the angle etc.

https://reverse-components.com/en/content/stem-calculator