Project Yellowjacket is a fat bike build based on 38 Frameworks' Hogback, the first production carbon fiber fat frame. I contacted Bruce Martin of 38 Frameworks in November 2012 when the frame was first announced, and we agreed that getting this carbon fiber frame immersed in Alaska’s winter cycling scene would be great for the fat bike community. As a “test rider” for 38 Frameworks I’ll be running the Hogback through the paces of training and racing in Alaska, and providing feedback to Bruce as needed. Check out 38 Frameworks’ website for further details about this new fat bike frame: http://www.38frameworks.com/hogback.html
Build Phase 1—Wheel Build with Simon: Photos 1–6 (19 January 2013). Parts: Surly Marge Lite rims (707 g and 703 g, as measured), Hope Pro 2 Evo Fatsno hubs (252 g front and 348 g rear, as measured), DT Competition Double Butted spokes (60 g/ten spokes, as measured), brass nipples (9.5 g/ten nipples, as measured), and Hope Fatsno QR Skewers (63 g front (135 mm) and 69 g rear (170 mm), as measured). The goal for this wheel build was to achieve a relatively lightweight fat tire wheel. The Marge Lites are 65 mm wide and are thus narrower (and lighter) than the much more commonly employed 70–82 mm fat rims, and the Hope hubs seem to strike a great balance between weight, reliability, and cost. This setup will no doubt sacrifice some flotation and tire stability at low pressure in soft conditions, but it’s a tradeoff I’m willing to experiment with for some notable weight reduction in rotational mass (Surly Rolling Darryl (82 mm) is reported to be 860 g vs. Marge Lites reported as 690 g). Also, note that the rear wheel for the Hogback frame must be built with a 21 mm offset (or 10.5 mm, depending on how you “slice” it); if in doubt, contact 38 Frameworks about building a rear wheel for this frame. To my knowledge, this is the only 170 mm rear hub-equipped fat bike frame that isn’t symmetric, but with this offset this frame permits clearance of massively wide tires and wheels (I will comment more on this later). A couple of other notes: building the wheels with Simon was very fun indeed, and the yellow Marge Lites were the inspiration for dubbing the project “Yellowjacket”, as the rest of the bike will chiefly be black.
Build Phase 1A—Tires and Rim Strips: Photos 7–8 (27 January 2013). Parts: 45NRTH Hüsker Dü tires (26x4.0” and 120 TPI) (1233 g and 1227 g, as measured), Q Tubes Superlight 26x2.4–2.75” (241 g and 249 g, as measured). I had originally planned to use 45NRTH’s newest tire, the Escalator, due to its speculated light weight and high thread count (180TPI), but the production tire ends up being somewhat heavier than some had speculated (certainly not 1100 g, and I measured one at 1260 g). Furthermore, the Escalator tread pattern may not be as great of a match for interior Alaska’s winter trail conditions as the Hüsker Dü’s pattern is, so I went with the latter tire (which is becoming a very popular choice for fat bikes). The rim strips comprise one wrap of black Gorilla Tape, with strapping tape employed as additional backing support behind the rim cutouts. The rim strips bulged as expected when we seated the tires’ beads at high pressures, but at the lower real-world pressures of winter biking I hope that these lightweight rim strips will serve this bike well (and it gives me the chance to include duct tape in a bike build, because that’s the Alaskan way!). For you weight weenies out there, check out http://fat-bike.com/2012/01/tire-weights-for-fat-bikes/ and http://fat-bike.com/2012/03/lighter-fat-bike-tube-alternatives/ for some perspective on fat bike tire and tube options, and some insight into how much fat tire weights can vary within one make and model.
Build Phase 2—Frame and Parts: Photos 9–18 (14 February 2013). Parts: 38 Frameworks Hogback frame (1640 g (3.62 lbs), as measured with seatpost collar and derailleur hanger), Carver O’Beast carbon fiber fork (575 g, as measured), Shimano XT double (38-26) crankset (weight not measured), XT 9 speed rear derailleur (weight not measured), XT front derailleur (double) (120 g, as measured), XT 11-34 10 speed cassette (324 g, as measured), XT 10 speed chain (282 g, as measured), Shimano Dura-Ace 10 speed bar end shifters with Paul Components thumb shift adapters (weight not measured), Avid BB7_MTN brakes (rotor 118 g each, as measured; caliper 218 g each, as measured), Avid Speed Dial 7 brake levers (90 g each, as measured), Race Face Next SL seatpost (245 g, as measured), WTB Rocket V Team saddle (231 g, as measured), Race Face Next SL handlebar (175 g, as measured), Planet Bike corky grips (36 g pair, as measured), Race Face Turbine 100 mm, 6 degree stem (138 g, as measured), crankbrothers eggbeater 2// pedals (279 g pair, as measured). As was the case with the wheels, my goal with the build kit was to achieve a high level of performance and reliability without taking too big a hammer to the proverbial piggy bank. I list the component weights here not in an effort to join the ranks of weight weenie-dom, but mostly simply for the sake of documentation and data collection. And, spec’ing out a bike build is rather fun, and recording weights is part of that fun in that it provides context to the overall weight of the bike (a non-trivial thing, even if you aren’t a weight weenie!). The bike frame shipped directly from 38 Frameworks’ frame builder via two day air on Tuesday (12 February 2013), and I had FedEx hold the package at their airport facility in Fairbanks so I could pick it up as soon as it arrived early Thursday afternoon (14 February) (this pick up scenario was Simon’s idea, and a good one indeed in that it saved us several hours of additional waiting around). The frame was shipped in a large bike box and was very well secured and protected. The fit and finish of the frame are quite good. Although I know little about bicycle frame building, I very much appreciate fine craftsmanship and the frame meets my expectations of fine craftsmanship. The measured weight is within ~25 grams of the reported weight, which seems to be quite good considering the frame is hand-built. Simon and I were working on the bike build soon after I had picked up the frame from FedEx. We were working on a deadline as Simon had a flight to catch later that evening, so we hoped we wouldn’t encounter any serious difficulties. The only issue we came across during the build was that the 10 speed rear derailleur (XT Dyna-Sys) was not compatible with the 10 speed bar end shifters (different actuation rations, it turns out). Simon knew something was up as soon as he started to adjust the cable tension. After a quick check of the derailleur hanger alignment (it was fine), we pulled a 9 speed XT rear derailleur from another bike and all was shifting well in just a few minutes. We (well, Simon, really) had the bike built by dinner time, which I thought was pretty remarkable! The complete bike, with pedals, weighed in right at 27 lbs, which is pretty respectable for a geared fat bike. A brief preface to my “Initial Impressions” blurb that will be coming soon: As of this writing (18 February 2013), I have 100 miles on the bike and am very pleased with the ride quality and characteristics of the frame and fork. Also, the components leave me wanting for nothing, and mechanically the bike has performed flawlessly. Simon’s excellent work in building this bike in the hours leading up to his departure on an international trip kept me out of mechanical trouble as I ventured 40 miles into the White Mountains this past weekend on a bike that had in fact only been a bike for a day and a half. It seems that 38 Frameworks has brought a very well-executed carbon fiber frame to the fat bike market, and riding it is a true pleasure!
Riding a Bike: Photos 19–22 (posted 28 February 2013). I’ve been riding in the White Mountains the past two weekends on overnight trips to the BLM cabins out there. The bike is still “running” like a top, and I continue to be impressed with the frame, fork, and overall build. I’ll have nearly 300 miles on the bike before this upcoming weekend is over. I’m keeping a running list of observations I’ve made about the bike during those miles in the saddle, and will post them here in the upcoming weeks.
Racing: Photos 23–31 (posted 7 April 2013). March was the month for racing, with three races over four weekends. March 9th marked the inaugural Chena River to Ridge event, with 25 and 45 mile races. I opted for the 25-miler for a variety of reasons, not the least of which was that I was slated to race the Homer Epic 100k the following Saturday (March 16th). The trail along the 25 mile loop was mostly in good shape, however, a punchy section of trail (along with some insight from a fellow racer) yielded a great opportunity to learn about the importance of dropping tire pressure in soft/punchy trail conditions. Dialing in air pressure for the conditions is likely especially important with my current wheel setup, which as I described above is relatively narrow for fat bikes. It was a good race, especially if you like climbing, and I came in 1st (disclaimer: many of the local speed freaks were racing the 45-miler). The following weekend I drove down to Homer for the Homer Epic 100k. Excellent driving conditions and overall good weather extending from interior to south-central Alaska boded well for nice trail conditions, but I was still a bit apprehensive about soft, deep, and/or drifted snow conditions in a part of the state that I’m not too familiar with. But, as it turned out, I had nothing to worry about. The trail was firm, fast, and 16’ wide for all 100 kilometers! It was truly an epic race, and I had a good day on the bike and finished in fourth place. My final race of the fat biking season was the inaugural Tanana River Challenge (~75km/~45 miles). The first ~5 miles had some drifted/punchy sections of trail, but I had aired down at the start in anticipation of this and didn’t seem to fair too badly compared to the other cyclists that were out front. The trail got a lot better as we approached Fairbanks, and I came in 3rd place. The bike performed flawlessly (I may sound like a broken record saying this, but it’s a good record) throughout the 130 miles of racing in March, and seems to really like being raced; it now feels like a trusted, old friend and has more than lived up to my expectations. I was pleased with how I placed in these three events, but most importantly I felt like I had “my race” each time out by being consistent and staying on top of hydration and caloric intake (neither are especially easy tasks while (winter) racing). All in all, a great racing season on great fat bike, and I sure did have fun! See the following links for more information regarding these races: http://cr2r.endurancenorth.org/ http://www.homerepic.com/ http://tananariverchallenge.org/
Acknowledgements: I gratefully acknowledge and thank several people who have supported this project, including Bruce Martin of 38 Frameworks, because without Bruce’s support and innovation this bike build would never have gotten off the ground nor even been a possibility; Kevin Breitenbach and Jeff Gillmore of Beaver Sports; and Simon Rakower. Simon deserves special thanks for willingly serving as "senior advisor" to me throughout the various phases of this bike build, and for providing his wheel building expertise and serving as master bicycle technician on this project; Simon's extensive knowledge of the science, engineering, and art in all aspects of bicycles is truly remarkable. Also, I thank and recognize Rocky Reifenstuhl, a friend and colleague who is an inspiration to me in countless ways. Simon and Rocky undoubtedly have more combined snow biking knowledge and experience than any two other people involved in the sport, and I consider it a fine privilege to have their keen insight on these matters. And, thanks to Mareca Guthrie and the many family members and friends that don’t presume I’m crazy just because I have so much fun building and riding bikes. Finally, here’s to my mother, Kathryn, who probably rides more miles on a bike during any given week than I do.