Friday, January 18, 2019

1983 Mantis XCR

We've all had those projects that take a long time to finally track down or proverbially 'land', or ones that sit there languishing for ages while you find that missing piece or maybe there is a major repair that takes a while to complete to your degree of satisfaction. Well, for me this Mantis was all those rolled into one hot mess. I was looking back at the date on the original photos I had of this bike and was shocked to see they were from March of 2013. Then I remember that getting the bike took a while and a quick search of my emails revealed that Richard Cunningham first emailed me about the bike back in the summer of 2012. Had I known what I would be getting into with that bike when I first got it, and that I'd find two others in much better shape I may have passed on it. But now seeing it all done and looking amazing, I'm kinda glad I stuck with it. After all it adversity builds character or something...

The bike had an interesting history. As I mentioned it was RC who scored me the lead. The current owner said he purchased the bike from the original owner a long time ago, perhaps in the late 80s. At the time the bike had been painted in a wild neon multicolored tape peel style paint job, the remnants of which were still present on the fork steerer when I got it. He rode the bike for a while until it was apparently stolen as retribution for some sort of drug deal or something like that. Fast forward a few year and the guy was visiting some of his old, ummmm.... friends? in Mexico and saw the bike there and apparently stole it back. He then stripped the cool old paint and painted it Chevy engine blue to hide the brand and details. I don't know how much of that story to believe but it sounded interesting at the time. He held onto the bike for a few more years replacing worn parts and making some questionable upgrades, but at some point the bike went into storage and sat around for a few years. When he decided to sell it he reached out to RC looking for some guidance on value and RC sent him in my direction. After a few months of negotiation we agreed on a price and I took it home. At the time it was the first fillet brazed XCR to surface and so naturally I was quite happy, that is until I started digging into it a bit.

I'll spare you guys some of the technical details as I've discussed them before in the post for another XCR I restored a few years back, so feel free to check that post here. I have since found a good scan of the original XCR one page flyer and have included it in this post in case anyone wants a bit more info on the bike. I'll try to focus this post more on the actual restoration of the bike and some pics of the finished product.

Here are a few pics of how I originally found the bike. As you can see not only is the bike in rough shape with damage to the seat binder but also a majority of the parts are missing. Luckily the fork was there, though it was not without issues. More on that later.

I saw the damage to the QR binder right away but it was just the tip of the iceberg. Further inspection revealed small cracks in the seat tube and some buried damage in the seat cluster. In addition the rear brake cable routing was converted from full length housing to a more modern cable stop design.

I'm not sure why someone would try to cut off the QR, perhaps the original assembly that was housed inside the binder and was somewhat unique to this frame was missing and someone assumed they had to remove the binder and get a collar. In the end it seems that they opted to install a traditional QR instead. None of that mattered as the seatpost used was undersized and so the whole area was pretty rough and it was immediately obvious a new binder assembly would be needed.

Being that RC got me into this mess I reached out and asked if he'd come over and check it out and maybe help me with some repairs. A short while later he paid a visit and we chatted all things Mantis, which was pretty cool. Side note, among all the people responsible for the early days of mountain biking RC is a class act. Talking to him is never feels like one sided conversation where either I ask a lot of questions or he waxes on poetic about the impact he made to this and that. It always pleasant and informative without being overbearing or holier than thou. Anyways, moving on. RC agreed to repair the frame and I sent it to him a few months later. Well, as things go RC moved from LA to SD and didn't have easy access to his airplane shop and wasn't really able to make any progress on the frame, damn! Prior to sending the frame to RC I reached to Ken Beach (henceforth refereed to as KB) to make a new seat binder assembly. KB did a killer job on that even providing a Suntour QR cam fully assembled into the new binder, which was actually a left over original Mantis inventory.

In case you haven't heard of him, KB was the founder of Gecko cycles and got his start at Mantis and had a few spare parts from those early days. He put together a new binder bolt which I had provided to RC along with the frame. RC recommended I reach out to KB about the repair saying that he would probably do an even better job.

Ken didn't disappoint, the finished product speaks for itself though. Although I only snapped pics of the seat cluster repair, he also properly repaired a previously damaged rear brake post and reinstalled the proper cable guides for the rear brake. In addition I managed to talk him into making some replica stems, bars and another fork for some other projects I had in work. Naturally while looking over the original fork from this frame (frame and fork have matching serial numbers naturally) he found a crack and ended up needing to replace one of the blades.

The stems with triangular face plates were the original Mantis design and were later replaced by the more traditional clamp style with fillet brazing at the clamp. The early style stems called the S-1 were painted silver while the later stems were chromed. The bars are straight gauge 6061T6 Aluminum with 0.120 wall thickness and Ken made some perfect full length replicas in a couple of bend options.

The remaining parts were the custom seatpost, modified Campagnolo cranks and Campagnolo quick release adapted to work in the seat binder bolt. I managed to find an authentic mantis post (check pic in the final gallery below) so luckily I didn't need a replica post for this XCR. KB provided a Suntour lever which worked perfectly, but all the wheel QRs would be Campy and so like the original equipement I wanted a matching Campy QR for the seat post. Getting that done actually required sacrificing parts from three complete QR / binder bolt assemblies. The QR arm from a wheel QR, the larger diameter rod from a Suntour seat QR and the female end of a campagnolo seat binder bolt, plus a spring from a Shimano XT seat QR.

The cranks are normal Campy Record road cranks with a 130mm BCD which RC had originally modified to accept a 74mm BCD granny gear. I found a couple sets of cranks and had them polished and reanodized and then with some big help from Tashi over at the Vintage Mountain Bike Workshop had the drive side arm match drilled to accept a granny gear. Fun fact, the bolts used to mount the granny gear are the male half of a Sugino seat binder bolt. Campy made actual adapters like these but they were very expensive back then, and silly money now. So, both RC and I opted for the budget version.

After assembling these I realized that RC seemed to have actually used Campy track cranks and not doubles, so I shaved off the inner chainring stops and added a countersink for the chainring bolt to prevent anything from snagging the chain while shifting. In the one of these cranksets took probably 15 hours of work to complete, small price to pay for perfection. Each crank would be mounted with a Campy alloy bolt and covered with a Campy cap.

Once all of the parts were made and the frame repairs were complete all that remained to get the decals and get the frame, fork and stem painted. For this project I decided to go with the legendary Joe Bell and unlike all the other XCRs I've seen which were painted red we decided on a custom metallic baby blue. I think the end result speaks for itself...

The drivetrain on this bike is comprised of Suntour Mountech derailleurs, Phil Wood hubs with a 6-spd Shimano 600EX freewheel and Suntour power shifters. The front gear chainrings are 28/42 and the rear spread is 13/34, making for a fairly usable 2x drivetrain, that is if you're fit.

The raised fillets are a trademark of these early Mantis bikes, they are very distinct and unlike any mountain bike of the time.

The headset is a Specialized alloy which was one of the nicer mountain bike headsets on the market in those days and a great alternative to using road headsets.

Tell me that's not one of the sexiest fork dropouts you've ever seen. 

Here's a good shot of the Mantis seat post. Because long seat posts were not common back in the early days of mountain biking many builders resorted to making their own. In this case RC made a custom Aluminum shaft and then cut off the head off of a Shimano DX BMX seatpost (which back then were cheap and plentiful) and pressed it into the shaft and then swaged the shaft down to secure the head in place. The seat is a Selle San Marco Anatomica and I managed to find on in Hungary, thanks eBay!

The seat cluster is easily my favorite part of this bike. Not only does it function really well with easy open/close action the final integration looks amazing, nearly organic. 

Once again, I am simply floored at the work KB did on this bike. I've had a couple other early Mantis frames in the shop since this bike and you can't tell that this frame was repaired. It's really great to have access to all these great craftsmen who not only were there originally but are still involved in the industry and willing to lend their skills to keep these machines alive!

Brakes are refinished Shimano M700 Deerhead units which fully refinished right down to the toe adjusters! Tires are IRC X1 in 1.75 width, which match the sport demeanor of a race bike.

From what I heard from ex Mantis racers and riders these bi-plane forks were not the strongest, but they sure look amazing.

One last little tid bit and one of the more challenging parts to find for this bike were the Durex Ambrosio rims. These were some of the earliest purpose built lightweight mountain bike rims and were specified on only a few high end bikes. While light and fairly durable the rim walls were not rolled and so tire beads would easily pop out of the rims, or so I've been told.

I really can't believe that this bike is finally done. Looking at it sitting here I can't help but feel a strong sense of both relief that it actually came together but also accomplishment that I managed to get it together despite all the frame issues and the seemingly never ending hunts for the rare and obscure parts needed to complete the build. With any luck I'm hoping to get this bike a spot at the Mountain Bike Hall of Fame in Fairfax, which I think would be a fitting end for a rare and beautiful machine like this one.


  1. Such a great restoration. I am humbled. Thanks, RC

  2. I'm reading and symply have been talking with Richard, are just a point of reference in the romantic and fashinating word of vintage mountain bikes...chapeau!