bespoke stiffer tandem blades from Reynolds or Tange im Album #ll Proto DIA Cunningham O Potts (MountainTrans & Team Trailmaster Archive)🔧🔗

Reynolds 531 22mm round track fork blades had good looks, but then there were also 24mm oversize diameter ones for sprint track racing or tandem use. Both an option in 80s steel choice also available in addition as 2 diameter variation oval profile blades..

Some early custom 80s forks (Joe Breeze & Ross Shafer) used tandem rando touring blades, or round oversize track blades for dedicated offroad Atm/Mtb downhill bombing or loaded mtb touring. Such tandem forks were made with 531 to get the right tubing for the job that was then man enough (a reinforced steerer was key on actual tandems). While other steel tubing manufacturers could be considered, Joeys series-lll Breezer forks turned out to have designated Reynolds tandem blades while Steve Potts for example mainly build his actual frames with Tange tubing.

Fork crown construction deserves a special note here. While Breeze and Potts used Cunningham socket style tubular crowns to insert oval Reynold tandem blades. Ritchey and Ross of Salsa made their earliest fork crowns differently each their own but similar in looks, only to use extra strong 700c blades and shortened them to proper length of the 26" Wheel.

http://bikeretrogrouch.blogspot.com/2013/12/reynolds-tubing.html
https://kuromori.home.blog/reynolds-531/

531 on order in the 80s
https://kuromori.home.blog/reynolds-531/#80s

Essentially, the specific versions of Reynolds 531 variants provided the robust characteristics that frame builders sought for the nascent sport of mountain biking before more specialized, lighter-weight alloys like Reynolds 753 (later in the 90s) and modern 853 became common for MTB applications.

Reynolds 531 types were used when maximum durability and stiffness were required for large riders or rugged off-road tandem use.

a nice testimony,
https://www.vintagemtbworkshop.com/1983-breezer-series-iii.html
see info on the forks construction

https://www.facebook.com/vintagemtbworkshop/posts/pfbid0sRSeFhvVyGnuHZBta43BJPctZLgnTWYjCxmYp4UHyaAyq7aBvTKgThZzEUKHdTZBl

To conclude, ..
Charlie made the very first modern designs of "Unicrown" tubing which Gary Fisher proudly took to Japan (forgetting himself to mention CC).

After this later on in Cunninghams Infopack after Unicrown Royalties were shared again, what C. called a typelll fork was offered as special optoin offer to ligher riders or dedicated touring.

Whether or not a round unicrown tandem blade tubing was available in the early 80s (to be precise 83) first by Reynolds or Tange hard to determine.