This one has been done for awhile, but I am just getting around to writing about it now.
September 2019 I began making a bike for my wife Gabby’s birthday. Its not easy to build a bike in secret when you live with the person… and when her birthday rolled around a month later I had a box of parts, mitered tubes in the jig, and an apologetic smile. Good thing she loves me. Almost 6 months late, I finally had completed the frame and built it up for her to paint. Here are the results:
The frame was made of roll-wrapped tubes from RockWest Composites, and as this was intended as a really tough off-road bike, I went a little overboard on the tube size and wall thickness. In fact, unusually for any bike, the toptube and downtube were the same size (albeit slightly different wall thickness). This was intended to make shouldering the bike less painful. The fork is a Whiskey CX/gravel fork with clearance for 700×45, and combined with the rear dropouts, provided mounts for optional fenders or rack on both front and rear of the bike.
The geometry of the bike was driven by three main factors. First, I wanted to replicate Gabby’s road position as faithfully as possible. This was a simple matter of checking geometry charts and doing some basic measurements. Secondly, I needed to make sure this bike was capable of serving both as a road bike and gravel bike, and also being usable with 650b and 700c wheels (this was a mistake in hindsight). Third, and most importantly- it needed to fit 3 large size bottles INSIDE the front triangle. Many of the gravel adventures we do require extended periods away from water stops and carrying bottles in the back pockets is never a fun time- you can’t carry enough food and your back gets sore. Most bikes with three bottle mounts put the third under the downtube- right in line with the dust/mud splatter coming off the front wheel. No thanks! The only real compromise I had to make for bottles inside the front triangle was toptube height- making the seatpost shorter and slightly limiting standover height.
The build on this bike was quite a bit more complicated than the road frames I’ve been making. The main challenge was the rear end of the bike. On the road frames I made, the seatstay assembly and chainstay assembly are one piece each, so getting the rear triangle lined up only required 6 total cuts/mitered joints. Since there isn’t a commercially available carbon fiber rear end for gravel tires, I had to make this from scratch. There were a total of 10 cuts, plus I had to create carbon dropouts and also a “notch” in the chainstays to fit the tire. For the brake mount, I used a Paragon steel flat mount plate and bonded/over-wrapped to the dropout plate. The dropouts themselves are also paragon, intended as “inserts” so you can change them between different axle types/widths, etc. I did not bother bolting, I just bonded them in for a low hassle solution.
For components, I picked 2×11 Shimano Di2- I got a great deal on a partial group from my teammate and completed the ensemble with a GRX 46/30 crankset, 11-34 cassette, and a clutched Ultegra RX rear derailleur. I chose mechanically actuated disc brakes from Juin Tech- the F1s. So far these brakes have exceeded all expectations- they are much stronger than cantilever or rim brakes, and while they are not as good as the Campagnolo H11 brakes on our tandem, they are plenty strong and have adequate pad clearance. The other real benefit to this system is a lack of maintenance- they are much much less fussy than hydraulic.
Wheels and tires were provided generously by Peter at Phil Wood. The rims are Hunt- 35mm front, 50mm rear with 38mm GravelKing slicks, set up tubeless. The hubs are custom anodized purple Phil wood Pro laced with Pillar rainbow spokes. Funny story about this build- when Peter asked the Hunt rep for a set of carbon rims for a gravel bike, the rep of course wanted to know what they were going to be laced to… and when Peter showed him these crazy rainbow spokes, before you know it Hunt is releasing a special edition of their disc wheel with them! Gabby is a trendsetter 🙂
There are always areas of improvement, and after almost a year on this bike Gabby has given me some notes for next time. The number one issue is the geometry. While it is acceptable across a range of wheel and tire sizes, in reality she only ever uses the 700×38 wheels and being optimized for that size would probably make the bike handle slightly better. This isn’t really an issue day to day for her but it’s something I think about a lot. The other issue is weight- this is almost a feature in that this thing is tough as nails, but the other side of that coin is that I definitely included some redundant material. Next version will be slightly more svelte!
Thanks again to Peter at Phil Wood for the help on this build, and to Gabby for putting up with my lateness. Next up: designing a frame for 3D printed Ti lugs!
OTB Engineering 