TPC Retro Build #2
Another build in the works, this time a very rare 1987 non elevated chain stay Mantis X Frame Valkyrie. This one is going to take some time!
This Mantis X-Frame could be from about 1986-1987 and precedes the Valkyrie. Here is the original prototype, which was featured in Mountain Bike Action Magazine.
There are not that many of them out there because it was eclipsed by the Valkyrie.
The bike is cracked / dented / ridden hard and hung up wet.
The bike belonged to Eddie Rae who was a builder for Mantis and this was his bike, he is the guy on the far right.
VX = Valkyrie non elevated
22 = frame size
1 = the first of 22 made
87 = the year it was made
We sent the photos over to Mantis founder and current Pinkbike Tech Editor, Richard Cunningham and he gave us some amazing, honest insight into the bike. Here’s what he had to say:
“Eddie Rea was my shop manager at Mantis and is one of my closest friends to this day. The non-elevated Valkyrie (we called them X-Frame) is the rare bird, as we only made a small number of them before I started to experiment with elevated chainstays and switched production to the E-version. We used “custom” serial numbers for our personal bikes, so I would not be surprised to hear that there was an unprintable phrase on the BB.The idea for the X frame came from an invitation from Gary Fisher to fly up to his bike company and do destruction testing on his new Super Caliber frames which featured the revolutionary Tange Prestige heat treated tubing. Gary was kind of angry because, as a contributor to MBA mag, I wrote that that particular frame buckled near the weld. The downtube must have not had a Tange DT, because when we pulled the fork towards the frame, the load cell ran up to about 700 pounds and then the frame tubes cracked open in three places as if they exploded. We then tested an oversized aluminum frame and it went up to 900 pounds before it buckled. (A standard chromoly frame buckles at 300 to 400 pounds.) Gary had an old Schwinn Excelsior cruiser frame laying around, so just for kicks, we put the big steel fork on the Schwinn and loaded it up – it went to over a thousand pounds and barely deflected when it failed. I went home thinking that, If a cantilever frame made from one-inch water pipe could out-perform a bunch of high-end mountain bikes, I should rethink the basic bike design.So, the X-frame used smaller. lighter main tubes and x-braces. I configured the rear triangle to catch the X-tubes to make the stand-over height super low. The bikes worked well, in spite of the fact that the smaller main tubes made them laterally flexible. The Achilles heel was that V-brakes had not been invented yet and the cable routing had to go around the seat tube. Special care had to be taken to get the brakes to work correctly. The BB was TIG welded, because that was a big piece of metal and it made more sense, but I fillet brazed the rest of the frame myself, and at the time, I was really good at it, so I left the joints unfinished to lord this over the other builders of the time. (thought I’d tell it straight, just once.)”
Cool stuff! This is going to be a fun and challenging build. Stay tuned for updates!