Cargo Cult Caldera

Drop bar conversion of 2009 Kona Caldera
Ceci n’est pas un gravel bike. (Image by the author.)

I wanted a gravel bike. I had some bits, some money, and, it turns out, very little taste. This is how it went.

What Went Before

For years I’d been riding an alloy hardtail frame from a now-defunct Cornish bike shop called Don’t Push It. The Dirty Jo F-Creme (“full cream”? I never did find out) was apparently the basis for the bikes used by the shop’s racing team, but all I knew at the time was that it was light, it was stiff, and it was cheap. I paired it with a boat-anchor Kona Project 2 fork with both canti and disk mounts. Classy.

The bike went through various incarnations, the last of which was the drop-barred, fat-tyred commuter/baby-hauler below. Feast your eyes.

Drop bar conversion of 2006 (?) Dirty Jo F-Creme
The prototype. (Image by the author.)

Lessons learned? First, 26″×2″ Schwalbe Kojaks are great. Are they Rat Trap Pass alternatives? Maybe not, but after a bit of running-in they were among the cushiest tyres I’d ever ridden. Next, drop bars on MTBs – once you get your position right – are fantastic. For the record, these are Ritchey VentureMax Comps on a stubby 70mm stem. Coupled with the non-suspension corrected fork, the position was low and the handling was – well, “responsive” would be the polite way to put it. It was an excellent commuting bike, first for London and later Birmingham.

All the same, after thirteen years of service, the F-Creme was starting to look a little battered. And not in an edgy, graffiti-covered subway train kind of way. The frame was dented and gouged, the forks were scuffed, and the Deore rear hub suffered from what turned out to be pitted cups, leading to a persistent, needling aural accompaniment of ticks and creaks. It was time for a change. I went eBay hunting.

Rolling Chassis

I landed on a green Kona Caldera frame in shockingly good conditon for forty quid. I didn’t have much reason to choose it over anything else except that, being a 2009 frame, all of my noughties-vintage parts would still fit: QR wheels, 1⅛″ straight fork, IS disk brakes, and a 68-73mm BSA crankset. As expected, it came together easily enough; all the F-Creme’s components carried straight over, though I kept the Kona’s zero-setback seatpost and WTB saddle. This was a mistake.

The Kona is longer and slacker (and, frankly, uglier) than the Dirty Jo, which, in combination with the scandalously short forks and zero-offset seatpost, pushed the saddle forward and lowered the bars. I felt like I was perpetually falling into the cockpit. The fix was to shorten the stem to 60mm, fit an FSA Gossamer seatpost with a 20mm layback, and replace the WTB saddle with an old Charge Spoon that allowed for yet more layback. It’s tolerable.

Drop bar conversion of 2009 Kona Caldera
Image by the author.

With the frame now built up, the creaky ghost in the wheelset came back to haunt me. By now, though, 26″ QR wheelsets – at least, those that might reasonably claim to be both good and cheap – were getting hard to find. I went eBay hunting again and ended up with a pair of 27.5″ Mavic XM319 rims on Novatec hubs to replace the 26″ XM317s on the old bike.


The bike rolls more smoothly than before but feels more sluggish with the larger wheels. Paradoxically, handling is still twitchy, probably due to the shorter stem. Tyres are 27.5″×2″ Schwalbe G-One Speed Addix, which measure up a bit small on the 19mm rims – they’re 47mm wide at most, but they may stretch out a bit over time. Like the wheels, they’re perfectly fine. Louder (both aurally and visually) than the Kojaks, and not quite as comfortable, but they do the job.


I moved the F-Creme’s drivetrain over wholesale. Veloce 10-speed shifters, Deore M617 crankset with a single FSA DH Pro chainring, a SRAM Apex derailleur and a Shimano 10-speed cassette. That’s a setup with a lot of caveats: homebrew 1×; no chain retention; components taken from different groupsets, disciplines, and companies. And though it had worked perfectly on the F-Creme, something was lost in the translation to the Caldera. The chain now dropped on a daily basis, where previously I had gone for weeks or months without problems.

I thought about adding a narrow-wide chainring, but when a single component costs more than your frame, you think again. Instead, I found a secondhand SLX front derailleur at a local bike shop (the excellent Birmingham Bike Foundry) and replaced the old FSA chainring with the 38/24 double that had come with the crankset. Set-up was hit and miss: neither the shifter nor the derailleur have a barrel adjuster, and I forgot to add one to the cable, but it shifts smoothly and dropped chains are a thing of the past.

Cable routing

On the ~scintillating~ subject of cable routing, I finally managed to solve a bugbear of mine. In the UK, the left brake lever controls the rear brake and the right brake lever controls the front – that is, the opposite way to much of the rest of the world. If you follow the cable routes offered by most frames, then, you’ll end up with the lefthand brake cable curving in tightly to pass by the headtube on the left, often rubbing against it as it goes. The same goes for the derailleur cables: the left/front and right/rear cables are forced describe tight arcs from the bars to the first cable stops on their respective sides of the frame.

What I did here was to have the lefthand cables cross the headtube to pass on the right and the righthand cables cross to pass on the left. They meet the cable stops under the top tube on their respective “wrong” sides of the frame and then travel to the stops at the rear of the tube. There, at the seat cluster, they cross back to the correct side of the frame. This entails some relatively tight curves, I grant you, but at least the cables aren’t rubbing the frame each time I turn the bars. Shifting performance is good, too.

Drop bar conversion of 2009 Kona Caldera
Brake and derailleur cable routing. At the front of the bike, the cables cross the headtube to the “wrong” side of the frame so as to describe a gentler curve… (Image by the author.)

Cable routing detail of 2009 Kona Caldera
…then cross over to the “right” side of the bike at the seat cluster. (Image by the author.)


I have created a monster: a gravel bike that assaults the eyes and the sensibilities in equal measure. But that’s okay, because this is an incredibly fun bike to ride. There’s a lightness to it – a spring in its step – that seems to come out of nowhere. The stiffness of the frame is part of it; the twitchy handling that should make it a chore to ride is another. Yes, it is ugly. But you can’t see its awkward profile when you’re riding it, and its handling quirks melt into the background after the first few corners. Long live the cargo cult Caldera!


Component Model Notes
Frame 2009 Kona Caldera 18″
Fork 2006-ish Kona Project 2 405mm axle to crown. Allegedly triple-butted.
Hubs Novatec D042SB-SS-11S (rear) and D041SB (front)
Rims Mavic XM319 27.5″, 32 hole
Tyres Schwalbe G-One Speed Addix 27.5″×2″
Brakes Avid BB5 Road
Shifters Campagnolo Veloce 3×10
Front derailleur Shimano SLX M665 (?) Double
Crankset Shimano Deore M617 38/24
Rear derailleur SRAM Apex 10 speed, mid cage
Cassette Shimano Deore HG50 10 speed, 11-36
Bars Ritchey VentureMax Comp 42cm
Stem FSA Omega 60mm
Headset Ritchey Comp Cartridge Logic
Seatpost FSA Gossamer
Saddle Charge Spoon