Sunday, February 17, 2019

1982/83 Mantis Sherpa

Richard Cunningham started building bikes in 1981 and officially launched Mantis in 1982 offering two models of bikes; the TIG welded Overland and the fillet brazed Sherpa. Both bikes shared 4130 oversize chromoly tubing and geometry only different in construction techniques. Both bikes were designed with a slight bend towards comfortable touring but accommodating of the idea that sometimes things get hairy. That being said it wasn't until 1983 that Mantis released the XCR which was meant to provide a platform for all out racing while the Sherpa and Overland became the defacto touring bikes. Like the fillet brazed XCR the Overland was only available for the first couple of years with both bikes getting replaced by the composite XCR starting in 1984, but the Sherpa remained in limited production for another couple years. It's hard to know for sure, but my limited serial number log indicates that approximately 20-30 Sherpas may have been made in it's four to five year production run.


I've spent a lot of time recently working on cough-cough, modern bikes and looking at these relatively slack angles and that crazy long rear end feels odd, but for the time this was relatively sporty geometry. The Sherpa and XCR were very similar in both their design and construction, with the Sherpa employing longer (18" vs 17.5") chainstays made out of standard 4130 chrome moly tubing vs smaller Columbus stays on the XCR. Both bikes had approximate 72 degree head and seat tube angles and similar builds including a Mantis stem, bar and seat post. Aside from the name decal you'd be hard pressed to identify the two at a distance. One nice thing about the Sherpas over the XCR is that they came standard in a variety of elegant metallic colors to the base Imron red on the XCR, a color I never really liked.


If you've not seen it before the Mantis three bolt stem can be a bit confusing. It features TIG welded construction on the quill and stem with a removable Aluminum face plate to enable easy bar swaps and provide a cable stop for internal cable routing. A very slick design that's truly one of a kind.


The fork here is the same exact unit used on the XCR and it's as elegant as ever. The bi-plane style of forks are some of the more distinguished hallmarks of early MTBs. Many of the first MTB manufacturers used this design, but few made them as nicely as Richard.


While aesthetically pleasing these forks were not known to last, at least not on the XCRs. One interesting fact about the early Mantis bikes is that the forks and frames wore matching serial numbers, so you would likely know if the fork wasn't original. In this case the numbers match so we can rest assured this fork is original. Odds are anyways that if a fork was replaced it would be done so with a new unicrown model which was the design Mantis moved to on most bikes starting in 1984.





The raised and filed fillet on either end of the top tube is a signature Mantis feature and was only available on the Sherpa and the 1983 XCR. Richard did make a few custom one off bikes and a couple of them were also adorned with these beautifully sculpted transitions.


top tube fillet side

Unlike most modern bikes, unless they are something that came out of NAHBS most modern bikes are all function and offer little in the way of flourishes or what I'd call personal touches. You pick a bike based on technical specs and maybe some degree of brand loyalty, or maybe just go with what's on sale because they are all so damn similar anyways. On these older bikes, and especially something like this Sherpa there is so much to notice, so much to appreciate. So even though I just finished the XCR (which I wrote up here a few weeks ago), I am still quite thrilled to have a chance to work on this bike and take in all of it's finer details.

 seat cluster rear




I like how Richard integrated rack mounts into the seat stays, looks much cleaner than externally brazed on bosses.


One of the main differences I've noticed between this Sherpa and all of the XCRs I've worked on is this above the bottom bracket, Henry James style derailleur cable routing. This was the way the 82 bikes were shown in the Mantis brochure, which is why I initially thought this bike was an 82, however I recently got a hold of the first cut of the 83 catalog which also had this same exact style routing. The later 83 brochures showed the revised style of routing and so I imagine at some point that year Richard switched over. I've seen one other Sherpas with cable stops at the top of the down tube and one just above on the seat tube with a piece of housing connecting them which served as the routing for the front derailleur, with the rear still using the welded on guide. The XCRs had a custom made guide underneath the BB shell.



As I mentioned earlier on the major differences between the Sherpas and XCRs was the heavier duty and longer rear triangle on the Sherpa. The bullet ends on the stays are much more pronounced here and really give the bike a beefier though hardly brutish feel. 


Once again the details in the metalwork on these bikes are simply stunning. This is one of those times I wish I had the space and funds to keep each and every single  bike I come across, sadly this is not the case.



This has become one of my favorite shots to take, I especially love it on Manitous with their dishless rear wheels.


Stem top


Suntour Mountech derailleurs with Shimano Tourney Takagi XT cranks.


The Suntour Mountech rear derailleur is an interesting design with a custom integrated top pulley which sits above the cage pivot mechanism. About all I can regarding this unit is that it does function. Suntour evolved this design eventually including a three pulley system which was poorly received and ultimately the more modern design was introduced with the XC series of Suntour MTB components.





I only rode my 83 XCR a couple of times and as best as I recall I didn't really care for the very upright feel of the bike and definitely didn't feel very confident with the drivetrain and brakes. By most people's standards my most modern bike is quite ancient, however I feel that for most people a good mountain bike from the early to mid 90s is likely to be less of a limiting factor than say fitness or overall skills. However, these early 80s bikes really require you to slow down and ride entirely differently that you would on bikes from the 90s or even late 80s. You have to get your head out of the saddle and plan your shifts and braking points well in advance. Handling is good enough for most trails, but bikes were larger and so you're higher up than you might on a new bike and a big bike is sometimes tough to get around in tight quarter. With all that in mind I quickly realized that this wasn't a bike I would try to ride hard and eventually sold it. I have a feeling the same would be true for this Sherpa. However, I really wish the weather would improve so that I could take the opportunity to take a second try and see how this bike would fare on the most gentle east coast trails where I now live.

Saturday, January 26, 2019

1987/88 Merlin Titanium w/ dirtdrops

I've been a big fan of Merlins for a while now and have settled around late 80s, early 90s evolution as the ideal mix of refined construction, classic style and off road handling characteristics. That being said, the earlier bikes are somewhat more unique and interesting. There are fewer of the early frames around and so getting a hold of one is a bit more challenging, relatively speaking. I've wanted to build one for a while, but am not really willing to pony up for one given I don't think it would be different enough or better than my 1989 Merlin. As luck would it have it a friend of mine wanted to do a Merlin build around this frame using another Merlin as a parts donor bike and asked me to do the restoration, works for me!


At first glance it's pretty hard to tell the different evolutions of these bikes apart. A closer look reveals a few details. Probably the most obvious thing is the weld quality. Merlins are historically known for their flawless welds, which is definitely true for the later bikes. Well, those welders had to learn and it seems obvious that the learning came over the course of building many hundreds of bikes, like this one. This is frame #190, placing it somewhere in 87/88 and representing something like the 3rd iteration of the design. The welds here are chunky and rough compared to my bike (#1849) but much nicer than some of the earlier one like #50 and #80, so clear signs of improvement.


Unlike some of the previous iterations this frame no longer uses swaged head tubes and bottom brackets shells, it seems that Merlin was able to get larger diameter tubing suitable for those applications. A few other minor details include one piece cable guides routing all cables on the down tube and a seat stay mounted roller cam brake. Apart from that you have to really be anal retentive to notice little details like the slightly abrupt end of the seat tube and stick on one piece decals rather than transfer style decals used on later frames.


The build is a nice a mix of Wilderness Trail bikes and Shimano XT with a Steve Potts LD stem supporting WTB/Specialized RM-2 dirt drop bars. The fork is a bit of a mystery. It looks like someone just sort of made it. The dropouts are welded into the open ends of the blades without any sort of caps or ends, the welds are rough and the general finish looks rattle can.



The WTB fixed angle seat post is one of the more unique features of this bike and remains the elusive missing piece for my personal Merlin. Sadly these are hard to find in general, and most of the ones I've seen have been rather short.


Man I want that post, only in black!




I have yet to build a personal dirt drop mountain bike and this Merlin is certainly a tease, it's a shame it's a bit too small for me as I'd love to give it a try on the trails.


Clean and simple XT, in my humble opinion there is nothing better on a Merlin.



I've discussed this before in other Merlin writeups, but here it is again. The 30mm Merlin BB shell is the Achilles heel of this frame design. Not only does it make for a flexy junction, but it relies on relatively small bearings which wear quickly. They addressed this later on by integrating WTB's grease guard system, but it was still suboptimal in my opinion.


It should come as no surprise that a dirt drop Merlin would come from PCC. The original bike didn't have all of the WTB equipment aside from the rear brake, but it provided a great foundation for the final build.


I mentioned the seat tube finish earlier. What I'm primarily referring to is the sharp cut on the top and the slightly longer length above the top tube. Later bikes had a bevel on the outside of the end and the stub above the top tube was shorter. The seat binder was also a bit more refined knocking down some of the sharp edges seen on this frame.


Nothing better than a Potts made LD stem if you want to run dirt drops. When it comes to vintage bikes involving these sort of builds it's really tough to cut corners. In this case all the parts sort of fell together and everything more or less worked right off the bat. The only thing I left alone was the 8-spd rear shifter. The previous owner had upgraded the bike over the years including a modern 8-spd drivetrain including the barcons. Rather than swapping them out, I chose to put them into friction mode and all is well.


All in all this bike holds a certain allure for me. Quantitatively I know it won't be better than my Merlin, it won't be lighter or faster or any of those things and yet it's more unique and quirky which keeps me thinking it would be cool to have one. This is the slippery slope many collectors face and eventually have to reconcile. Sure, with enough money and space you can have one of each iteration or color or whatever, but personally I struggle justifying allocating my limited relatively limited resources to pursue collecting subtle variations of each make and model. I suppose my goal is to identify the bikes I like and and then find the best possible version of each one and then hang onto that bike! All the better if along the way I get to check out the competition on someone else's dime!!

Wednesday, January 23, 2019

1989 Bradbury Manitou

I've gone on a bit of a Manitou bender in recent months finishing four of these amazing bikes. It still just boggles my mind how long I searched and waited to get my first Manitou only to now have four sitting here all built up. It's really funny how things work out.



The particular frame in this post (first on the left) came from Doug Bradbury and was one of the frames sitting around his garage after he moved to Crested Butte. The frame is what I'd call and early-mid version of Doug's evolution featuring horizontal rear entry drop outs, box section chainstays, large gussets, externally butted down tube, pressed in bottom bracket and a necked down seat tube. Though Manitous famously lack serial numbers those design details combined with a few date verified entries in the build log book place this bike squarely in 1989. Below are a few photos of the frame as I got it from Doug, as you can see it was in pretty rough shape with a lot of oxidization all over the place. Another notable 'feature' of this frame is the sleeve on the seat tube. As Doug was experimenting with larger diameter tubing for his bikes he wanted ran into a lack of oversize seat posts. This mandated that the upper portion of the seat tube used small diameter tubing and there had to be a transition between the large and small tubing sections (as seen on another Manitou here). Initially the junction was down low on the seat tube and over time moved up until sometime in late 89, early 90 the entire length of the seat tube was 1 3/8 with only a small section above the seat tube necked down. This design proved to be problematic and of the three frames like this I've had all three were cracked at the junction. This particular frame must cracked a long time ago as Doug did the repair himself with a a large sleeve over the junction and the sleeve had about as much patina as the rest of the frame. This leads me to believe that the frame got a lot of use after the repair and so the quality of the repair is pretty good.


Heavy levels of oxidation and wear were all over the frame, but particularly bad on the BB junction. This early frame used box section tubing over the entire length of chainstay unlike the later bikes which used 1/4" plates at the BB junction. I've always liked this design for the amount of work it must have taken to build. The later design was simpler to manufacture and offered more tire clearance, but I feel this version is a bit cooler and more desirable.


The pressed in bottom bracket on this frame is also a short lived feature of early Manitous. As Doug started experimenting with wide hubs (think boost) he needed a longer bottom bracket shell and spindle to accommodate the chain line. Nobody made wide bottom brackets suitable for mountain bikes at that time so Doug did what many other builders did back then and used pressed in bearings and and a long (145mm) tandem bottom bracket spindle. Some of his early bikes even utilized grease guard style bearings, like the ones used on Cunningham and Potts bikes of the era.




The restoration of the frame involved mutliple levels of both mechanical and manual sanding and polishing over many many hours, but in the end I think the results speak for themselves.


I initially built this bike with a rigid fork, but kind of liked the look of the first generation Bradbury fork and happened to have a clean example with wide spacing which I think looks great on this frame. As I mentioned earlier when I got the frame from Doug is bare, without any parts. I was lucky enough to get a cache of old wheels and hubs from Doug but only a few complete stems which I have long since used up. Given I had a few more frames to complete I decided to make some replica stems and that's what you can see on this bike. The stem is virtually identical to the originals made by Doug and I kept the cable guide allowing me to use either a rigid or suspension fork.



While the fork was in great cosmetic condition the elastomers had long since given up the ghost. I rebuild them using new elastomers from suspensionforkparts.net which work nicely and are the only way to revive these iconic forks. I really like these forks, they don't do much for big bumps and they don't offer a lot of rebound but they just make things fun. In my opinion they look cool, much better than an RS-1 and they are very reliable. So, while it's undeniable that an RS-1 was a more complicated and probably high performance fork, I for one have never been impressed with one and they were rather unreliable often times blowing seals on long rides leaving you with a sloppy sack of oil for a front fork. That being said, I kind of feel like I should at some point do another RS-1 build, too bad I sold all my forks.


The front hub on this bike measures 115mm and was custom made by Doug. There were several variants of these hubs over the years. Early on Doug modified hi-e hubs with wider center bodies and longer spindles. Later on he started making his own hubs modeled after Bullseyes, again with wider centers and longer spindles. This enabled him to build stronger wheels to the point that a 28h front wheel was effectively as strong as a 32h or even 36h version.



Having just recently completed the gray 1990 DBM with front and rear IRD Switchback brakes I feel like I could throw and IRD brake on the front here, but I'm not sure it would be right on an 89, I think those came out a bit later. Still, the XT brakes while very functional lack a little bit of wow factor leaving some opportunity for future upgrades. I only had some Grafton brakes around and given the U-Brake on the rear I'd have to break up a pair of them and I just didn't want to do that.



The drivetrain is very basic 18 speed Shimano M730 XT, with Dia Compe brake levers which Doug seemed to like given how many pairs he had lying around and on bikes. The only thing I've been considering changing are the cranks as or maybe just swapping the chainrings for black ones, bike needs a bit more contrast, too much silver.


I was just thinking that in reality I don't actually know if the frame is cracked under this sleeve, for all I know Doug did it as a preventative measure. Probably not, but still a fun thought exercise. Time to hunt for a boroscope.


The rear IRD progressive brake features a custom made stiffener brace made by Doug for his bikes.


Rear hub is also a custom made boosted take on a classic Bullseye design. Measuring at 145mm the rear wheel was effectively dishless, again making for a stronger and stiffer platform. One of the traits DBMs have on the trail is what I affectionately dub their crudbuster capability. Much like a nice pair of fat skis busting through some crud a Manitou is rarely perturbed by trail conditions. A lot of this sort of thing comes down to rider skills, but normalizing around my riding style I've come away appreciating the Manitou's prowess and removing rather than adding risk attributed to technical trail riding from the equation. It probably boils down to knowing that if I point the bike there through that patch of rocks I'll come out the other side pointing the same direction rather than getting knocked off course or having to manage the traverse however brief it may be. Just my $0.02...


Th photo above and below show my favorite bit on this bike. I can still vividly remember the layers of oxidation I had to remove and the polishing approach that cleaned the tubes while trying to preserve the details of the welds... This was quite a challenge but it feels great to have the frame look this good in the end.




This little cable run is just fun, I don't know I love these little not well thought out add ons on these bikes. The cable routing on the early Manitous is all over the place, however by mid 1990 Doug had moved pretty much everything to the top tube and thee housing runs were cleaner and more direct.






I'm sure I sound like a broken record at this point, but these bikes just look the part of a race bike. In the end that's kind of what I love most about this era of mountain bikes. If it looks fast standing still it's likely to be fun off road and nothing rings truer here. This bike, with its giant repair and all is still so freaking amazing. Take one part rugged trials bike, tack on some forward thinking technology and wrap it in a handmade package and you have what in my mind represents the reason why I am so passionate about vintage mountain bikes. No fancy paintjobs, no crazy loud anodized parts just subtle performance for people who want to ride and explore. Period, end of story.