Adjustable handlebar extension riser
 

Cannondale Supersix 6 Tiagra (2013)
Recommended adjustable handlebar extension riser .
Trying to get a more upright ride...
Suggestions welcome.
Thank you,
Gary

Assuming you’re talking about a stem, but it’s going to be hard to provide a lot of good advice without knowing more about what’s on the bike now. There are adjustable stems out there, but depending on how you bike is setup now you may be able to accomplish what you want simply by flipping the one you have.

Personally, I’d be inclined to tell you to go to a shop and have them do a fit check Andy get a properly sized stem. Sometimes just raising the elevation won’t accomplish what you want if the stem is too long to begin with.

I've never seen an adjustable handlebar riser. You can find stem risers on Amazon for $10 on up but they're not adjustable.
Are you looking for an adjustable stem? They're not going to raise the handlebar as much as a riser - instead, they give you a choice of a little more height or a little more length.

Steer Tube extenders are adjustable in the sense that you can clamp the handlebars onto them wherever you wish.

I suppose, one question is what your existing steer tube is made out of? Steel, Aluminum, or Carbon Fiber?

Anyway, a lot of steer tube extenders available. Here is one, but a search should bring up quite a few more.

https://brandscycle.com/product/gian...r-273637-1.htm

https://brandscycle.com/images/libra...r-273637-1.jpg

Also lots of adjustable stems.
https://www.niagaracycle.com/categor...0-degree-black

https://cdn2.bigcommerce.com/server2....1280.1280.jpg

Also a number of non-adjustible riser stems. Although, you get some extra adjustment by changing or moving steer tube spacers if you have them.

https://www.greggscycles.com/product...m-258620-1.htm

https://www.greggscycles.com/images/...568-1-12-1.jpg

Oh, another thing to keep in mind is that if your bike has too much drop for you, then the frame may well be too small, so it is better to get the right frame than to try to hack it together.

Many people can also get used to bar positions at seat level, or slightly below seat level with simply spending more time in the saddle. I'm not convinced many riders truly need their bars above the seat.

FWIW I've always run risers and/or adjustable stems on my bike. But now I have 3 risers in my parts box because I haven't used a riser in 2 or 3 years. Today I removed the adjustable stems from my Marin and my Iron Horse because I realized I had the bars level with my seat anyway. The only bike I ride with the bars above the seat is my fat tire cruiser (well, and the adult trike, but that's a whole different beast).