I ran out of space on my handlebar which is narrow, about 20 mm, and looking for recommendations on an extender so I can attach some stuff like computer, lights, etc.
Thank you.

I'd say that bar is narrow. 20 mm is less than an inch

Topeak and Minoura both make the doodad that your looking for. Here's the Amazon search results for the Minoura Spacegrip https://www.amazon.com/s/ref=nb_sb_ss...fix=minoura+sp.

Ok I'm going to assume it's 20cm wide.

Why are you riding a 20cm bar? Are your shoulders 20cm wide? If it's for fashion purposes I get it. But honestly it's not fashionable to have a bunch of computers and lights and stuff or an extender thing on your super narrow bars....So you might as well just go ahead and buy a proper width bar and mount your fun bits on it and be happy.

Threadless type ?get a second stem just to pack the widgets on.
there needs to be sufficient steerer. height of course..

The Spacegrip can also be mounted on the stem.

Thanks for the suggestions. The bar is about 21 mm, so I think the Topeak Extender (thanks No1mad) will work with a shim. Planning to mount my front lights on it.

I have been thinking about getting one of these
https://www.benscycle.net/index.php?m...oducts_id=9587

Get a Dashboard Genie.! Geoman has the haif size one. I've read too many posts about extenders breaking. I saw a co-worker with the fully size one on his Civia.

peasy seems to be saying a measurement number , without saying what
he is measuring.

21mm where,? probably not accurately reading the ruler..
(ok, did say 'about')
Likely, bar diameter is 22,2 and 25,4 in the center..

21mm is under an inch. If it's the diameter of the bars then it's likely that the outer diameter is the standard 22.2mm. If you mean 21cm (210mm, approximately 8") for the handlebar width, I can only suggest getting some proper length handlebars. Aside from having more space to mount stuff, you'll be able to control the bike much better.

It's the diameter of the handlebar near the center. I used a metric ruler to measure the width, that is one side of the handlebar to the other side. Should I be measuring the circumference ?Thanks.

Yes, it's the diameter of the bars that you need to measure, to know what stuff can be attached, (not right at the center). A caliper measuring tool is very hand for measuring things like that and can be very cheap.

Aspire VeloTech has sexy carbon fiber accessory mounts. The short one is the same as the above Dashboard Genie but the double wide is twice that size.

https://www.aspirevelotech.com/Mercha..._Code=PCHBM-01

https://www.aspirevelotech.com/Mercha..._Code=PCHBM-01

although the shims are for standard 25.4-26.0mm bars.