Best website for 21mm straps

I use Martu Leather from Chile.  Every strap is custom. You can choose your exact width, length, stitching, colour, buckle, etc. to your preference.  
 

And she is still cheaper than most off the shelf straps. 

I'd be interested in the answers on this one. Longines Hydroconquest... brilliant in every way except the original, non-tapered bracelet which I could never get on with and a 21mm lug width which makes replacement a pain in the rear.

Watchgecko has some: https://www.watchgecko.com/lug-width/21mm-watch-straps

i will be the first to tell you I am not a strap guy, but on those occasions I have tried doing the strap "thing", I have never really had an issue squeezing a 22mm into a 21mm lug spacing. Perhaps this is a no-no, or it is frowned upon, but if you see a 22mm strap that you like, I would give it a shot.

Just my opinion... 

Have a couple you may want to peek at...

Lots of colors and sizes... Straphabit FKM straps

https://www.amazon.com/Rubber-Quick-Release-Watch-Strap/dp/B096TJ9VK1/ref=sr_1_5?crid=21PELEVBXR8MV&keywords=fkm+straphabit&qid=1647526493&sprefix=fkm+straphabit%2Caps%2C66&sr=8-5

Got the Sail cloth in multiple sizes and the NATO 21

https://www.zuludiver.com/collections/21mm-wide-watch-straps

Im new to the strap game but ive purchased a few straps from Aliexpress. I would stay away from the sub $5 NATOs but I got some good leather & Rubber ones above the $6 range. Especially above $10. Another is Ebay.

Etsy, hands down.  They have a number of well known and gifted strap makes that offer handmade straps in all sizes and can do completely custom orders.  Note, there are a fair number of drop shippers too, so read the reviews.

Have you checked out StrapsCo yet? They seem to have a bunch.

Me too.  I've never had a problem, and actually like the additional heft of a 22mm strap, especially on a bigger watch.

Yes GREAT shout! Really good customer service over at CheapestNato. I've been buying from them for a couple of years now.

I found one on eBay (UK) for the Hydroconquest. 21mm, rubber with milled clasp.. £27. Its certainly a better option than the Barton silicone strap I had on it previously. Barton...

eBay special....

I might give this a try!

Thanks all. Seems like a fairly simple request, and ordinarily one that can be met by searching around. However, for further context, not only looking for 21mm, but for two-piece straps, the short piece has to be at least 80mm. I have a thing (I'm sure I'm the only one) where I like the buckle to slightly pass 'mid-wrist' and be more towards the 6 o'clock side. Most sites sell 75mm or less for the short piece, which doesn't balance well on my wrist.

My go to, for at least leather straps up to this point, has been RIOS1931, but looking for more options, given the aesthetic of the Ocean Star.

Thanks for the suggestions and keep them coming! 

This is exactly why I use Martu Leather.  My wife prefers a size of 55/110mm which Martu will make for any style strap she sells.  Her average strap price is around $40 with no up charge for custom sizes.

That might seem cheap but the quality of the material and workmanship is terrific.  It is by far the best kept secret in the watch hobby despite me trying to tell everyone to give Martu a chance. 

https://nomadwatchworksmy.com/collections/shop-all-21mm

Mostly leather for odd sizes, but they do carry a lot of odd sizes! Big plus that they carry a wide range of quality, including alligator, Horween, ostrich, and more). I have bought 2 straps from them (alligator and Horween), very happy with both.
 

https://delugs.com/

Haven't tried these but they do carry odd sizes too.