There are plenty of places where one might draw an arbitrary line in the sands of realism with Warhammer 40K. Apparently one of my lines is bikes with fixed weapons and zero ground clearance.
Indeed with the exception of the Storm Speeder, most of the Primaris fast attack options don't do it for me for one reason or another… And that's how I got over 2,500 points into a marine army without painting a single fast attack unit. I did paint a Stormtalon, which is effectively fast attack, but still. Not exactly the paragon of Ultramarian flexibility.
I don't hate the stock kit, indeed I quite like the ridiculously en-chonkened Akira lads, but those things would've looked completely ridiculous on my moorland basing scheme. And then along came @scriv_paints on Instagram with his beautiful Raven Guard grav bikes. Now these, these I can see being more useful. There are a few grav bike conversion kits knocking around, but to my eye these do the best job of applying the modern Primaris aesthetic to the biker kit.
It ain't straightforward. For one, you need a 3d printer and the skill to use it. Or be friends with Jeff. Thanks Jeff!
He did most of the initial conversion work, snipping off the wheels and checking the fit before bringing them to Oxford. I then assembled them and filled in the gaps.
There are two main hurdles in the build. First is with the kit itself. It's one of the worst push fit kits in the primaris range, unless you cut off ALL the pegs, at which point it's fine. You'll still have some gap filling to do, and you'll want to leave the fuselage to cure overnight whilst held under tension by clamps or elastic bands, but other than that it's fine.
The second hurdle is the imperfect fit you get with the main thruster connecting to what used to be the rear mudguard. It's not perfect, so you'll need to use your filler of choice. I used green stuff.
Other conversion work: removing the stowed helmet
The sergeant on the stock sprue is bare-headed, with a helmet stuck on his thigh. I wanted everyone wearing helmets for high speed grav biking, so hacked the helmet away with my clippers, shaved it smooth with a scalpel, then carved in some panel lines. I was grateful to have done a fair bit of sculpting previously, or this might not have worked.
The structure of the stock kit largely precludes sensible sub-assemblies, so I didn't even try. The one concession I made on that front was keeping the bases separate until I'd done the undersides of the bikes and the bases themselves.
Painting itself followed the usual Cobalt Scions recipes and processes, although I very much employed drybrushing for the initial blue stages and tidied up with proper highlights and the base colour afterwards.
I imagine grav bikes aren't widely popular due to being far more laborious to maintain than a conventional bike. They probably also lack range, as you'd need far more energy to hover than to roll. I imagine the Scions are willing to put up with that, since they'd use Storm Speeders and aircraft for fast recon, and Phobos infantry for stealth recon. The bikes - as implied by their rules - would work more like shock cavalry, able to traverse any terrain and held in reserve until a crucial moment. This, of course, is broadly in line with the way the Romans used cavalry: as auxiliaries rather than mainstays.
Naturally it was mandatory to give Sergeant Antinus Severus and his floaty bros an entry in our campaign wiki and a unit portrait for use on my roster. Will he accrue any XP before 10th edition shows up? What will we even do with our Crusade forces as they transition into a new ruleset? Who the f--- knows? I'm just happy to have painted more toy soldiers.