Bikes of the Bunch: Santa Cruz Highball XC-Gravel bike

Blurring the lines between gravel and XC bikes to conquer Swiss mountains.

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In this week’s Bikes of the Bunch, reader Alex J. Wissmann shares his unique and wonderfully well-detailed Santa Cruz Highball cross country/gravel bike. Clearly a talented photographer, Wissmann is also an apprentice bike mechanic based in Biel, Switzerland. 


I wanted to create a gravel bike for tackling both technical trails and long gravel rides. Living in Switzerland, at the edge of the Jura mountain range, I’m often riding gravel roads with sections of techy singletrack thrown in. A pure gravel bike feels a little too under-gunned on those technical trails, while the fixed hand position of a cross country mountain bike is lacking on long gravel rides. 

My solution was to build a bike that blurs the lines between gravel and XC bikes both in terms of capability and components. 

The general idea of starting with a nice mountain bike hardtail frame was there from the start but I was keen on doing something a little different. It was about two years ago that I started with these ideas, some sketches, and a spreadsheet of parts with their cost and weight. 

An early sketch of what I was seeking to build. Some things, such as the 45 mm deep rims, didn’t make the cut.

I had a few requirements for the frame. I wanted a good quality cross country hardtail with non-progressive (aggressive) geometry. I really wanted a third bottle cage mount. And an English threaded bottom bracket was attractive to me, too. The Santa Cruz Highball frame fit the bill. 

Obviously, the Highball was intended for use with a flat handlebar, and so there are some important sizing considerations. As I’m at the edge of frame sizes, the smaller one of the two was the easy decision.

The finer aspects of the fit were a major consideration for a bike made for longer distances in the saddle. I compared a lot of geometry numbers with progressive gravel bikes I knew, mainly the BMC URS, which has kind of comparable numbers and I’ve ridden a few times. I sure was nervous about my selection until I got to ride it. 

Parts choices 

A huge amount of time and energy was put into the parts selection of this build, and some elements were certainly trickier than others. 

I really wanted to use Shimano GRX Di2 as I greatly prefer the shifter ergonomics compared to SRAM, but unfortunately, the maximum 11-46T cassette capacity was just too limiting. In my research, I stumbled upon the Garbaruk cassette and expansion derailleur cage which gave the GRX derailleur a far more generous 10-50T range. 

A Shimano derailleur with a 10-50T cassette.

Dialling in the shifting is harder with Garbaruk’s parts, but following in a break-in period of the cassette and chain I have been able to achieve pretty good performance – although stock Shimano is still smoother. However, I’m quite happy with the slight trade-off in shifting performance given it looks great, it gives me a wide gear range, and it shaves off weight. 

Chainring size was also a big question. Should I go with a MTB setup or more gravel bike gearing? After some calculations, I went with a 34T Rotor Q-Ring and I’ve been really happy. I’m rarely spinning out as the 10T in the back helps a lot up to 40 km/h+, meanwhile, I’ve got the gearing to climb up anything. Also, I love the oval chainring!

Picking tyres can be a tough balance between grip and speed. I wanted some grippy but fast cross country 2.25″ tyres and so Vittoria’s Barzos are what I use most. I’ve also got a pair of Vittoria Terrenos to use for faster courses. I’m also keen to try some 40 or 45 mm gravel tyres for some of those faster courses.

Wheels were an area of great deliberation. My first thought was some deep-section rims, such as the Light Bicycle Falcon WR45 Disc, but then I realised the aero properties would be trash with a 2.25″ tyre mounted. Figuring that, I sought to focus on ride quality. And after much hesitation, I landed on Duke’s World Cup-winning Lucky Jack SLS2 6Ters rims. These rims are front- and rear-specific, with the front offering a 28 mm internal width for more grip and higher radial stiffness (so they claim), while the rear has an inner width of 25.6 mm and is said to be less radially stiff for better shock absorption. 

I can’t confirm Duke’s claims as I’ve never tested them back to back with other wheels. Regardless, they certainly feel great. Mounted and inflated, those 29er tyres measure 57 and 56 mm, front and rear respectively.

I had no problem deciding on the DT Swiss 240 Exp hubs; after all, I basically live next to the factory. However, choosing spokes proved as tough as picking the rims. Emotionally I wanted to support my local company, DT Swiss, but I also really wanted an oil-slick finish that they don’t offer. In the end, Pillar offers its Wing spokes in a beautifully coated oil slick version and so that’s what I ordered. 

Rainbow spokes help add an extra splash of fun to the build.

Tubeless bits are from Duke.

Adding the XC flair 

A dropper post and a fork lockout were both things I wanted on this build. The dropper post was an easy one as there are quite a few dropbar dropper remotes on the market, and many of them work with the DT Swiss dropper I selected. And speaking of that DT Swiss dropper, I really like the fact that it’s mechanical and easily serviced.

However finding a lockout for the suspension fork proved truly tough, mainly, because as far as I know, there are no suspension lockout remotes for dropbars. 

With few alternatives, I converted a bar end shifter for the purpose and routed the cable internally through the bar. And it’s this internal routing that proved the biggest challenge of the whole build. 

Control of the fork from the drops.

I wanted a carbon bar with internal routing, Di2 compatibility, flat tops, a wide width, flared drops, and compatibility with clip-on bars. Oh, and it had to be possible to fit the bar-end shifter for the lockout. I was in contact with Beast Components from Germany, talking about a reinforced version for clip-on bars and some mods for the Di2 routing. In the end, they could not do it so I ended up with the Ritchey WCS Carbon Adventuremax. This bar works well, even though I would love a Beast handlebar.

While not a unique issue to Ritchey, there simply is not enough space in the handlebar for Di2, hydraulic lines, dropper and suspension remote cables, and so it ain’t the prettiest thing. Similarly, finding a place for the Di2 battery proved a challenge with the usual spot – within the seatpost – occupied by the dropper.

My solution to the battery dilemma was an older and recently discontinued PRO Tharsis trail stem. Luckily I found one still in stock and in the length I needed. This stem is quite special. It achieves headset compression through an externally threaded sleeve that is tightened with a 32 mm headset spanner. Doing this means the inside of the steerer is kept open for the Di2 battery. 

The stem has a built-in preload mechanism. This keeps the centre of the steerer open for the Di2 battery.

While the stem and steerer-stored battery work well, I’m currently thinking about how I may be able to mount the battery inside the frame. Doing this would free me up in terms of stem and spacer options. It would also mean there’s no risk of being stuck somewhere with a loose headset. Alternatively, I’m considering whether I should go with a SRAM AXS mullet groupset. This would be so much easier without all those wires or the battery, and I’d have one more gear. The shifter ergonomics remain my sticking point. 

And I might still add a small chainguide. The Q-Ring chain security is quite good but I’ve dropped my chain once and it caused some scratches on my crank.

Winning 

I was scared about how it would turn out but in the end, I’m really happy with the result and how it rides. It is quite different to a more racy gravel bike and does not thrive in the same terrain or kind of ride that such a faster bike would. 

I feel like I can push it quite far into mountain bike territory and keep up with friends on more capable bikes. The only hindrance is my position on the bike but those wide Ritchey bars sure do add a bunch of control. 

As you may expect, I’ve found that the bike just isn’t as lively as a more racy gravel bike. This is no problem most of the time but on pretty smooth roads in a race situation, it holds me back. Certainly, this bike isn’t the best of both worlds, but it’s just something different and I’ve certainly enjoyed riding it.

I refer to this bike as “ʻOumuamua”, a word that means “Scout” in Hawaiian (and is also used as the name for the first-known interstellar object passing through the solar system). I feel it’s a fitting name for a bike made to explore.

The build

  • Frame: Santa Cruz Highball CC
  • Fork: RockShox SID SL, 100 mm travel
  • Headset: Chris King Dropset 3
  • Rims: Duke Lucky Jack SLS2 6ters
  • Hubs: DT Swiss 240 (new style with Exp ratchet, XD freehub body)
  • Spokes: Pillar Wing 20 and Sapim Polyax Alloy (orange)
  • Shifters: Shimano GRX Di2
  • Crankset: Rotor Kapic Carbon, Rotor 34T Q-ring chainring
  • Bottom bracket: Chris King ThreadFit30
  • Rear derailleur: Shimano GRX Di2 RX817 with Garbaruk derailleur cage
  • Cassette: Garbaruk 10-50T XD
  • Chain: Shimano Ultegra
  • Brakes: Shimano GRX Di2 RX-815 levers, Shimano XT M8100 calipers, Campagnolo 03-AFS Centerlock rotors
  • Tyres: Vittoria Barzo, 29 x 2.25″, tubeless
  • Handlebar: Ritchey WCS Carbon Venture Max 46 cm
  • Stem: PRO Tharsis Trail Di2
  • Seatpost: DT Swiss 232 One Dropper, PRO remote
  • Cages: Fidlock
  • Bar tape: Supacaz
  • Saddle: Fizik Arione R1 00
  • Pedals: Shimano XT M8000
  • Extras: Custom tool/tube holder, Duke tubeless valves, Duke tubeless rim tape, bar-end shifter for suspension lockout remote.
  • Weight: 9.2 kg

Gallery

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