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!


Frame2009 Kona Caldera18″
Fork2006-ish Kona Project 2405mm axle to crown. Allegedly triple-butted.
HubsNovatec D042SB-SS-11S (rear) and D041SB (front)
RimsMavic XM31927.5″, 32 hole
TyresSchwalbe G-One Speed Addix27.5″×2″
BrakesAvid BB5 Road
ShiftersCampagnolo Veloce3×10
Front derailleurShimano SLX M665 (?)Double
CranksetShimano Deore M61738/24
Rear derailleurSRAM Apex10 speed, mid cage
CassetteShimano Deore HG5010 speed, 11-36
BarsRitchey VentureMax Comp42cm
StemFSA Omega60mm
HeadsetRitchey Comp Cartridge Logic
SeatpostFSA Gossamer
SaddleCharge Spoon