Shiny chrome bumpers and detailing, a 40K CC engine, slouchback seats made of real Kraken leather, 4' wide tires, and a pure Fenrisian steel frame? No, it's not the latest from some bad Discovery Channel show, we're talking about Swiftclaw Biker Packs!
Swiftclaws are another Blood Claw variant, this time on huge-ass motorcycles. Not only were they victim of the same unfortunate naming schema as their bretheren Skyclaws, much of the unit analysis remains the same too. What we get is a mostly another copy/paste unit, so go look at my Blood Claw article for their effectiveness calculations. Let's look at what is different:
1. Cost. 3 Swiftclaws = 5 Blood Claws or 4.17 Skyclaws. Said another way, once you hit 3 Swiftclaws it's cheaper to just buy Blood Claws in a Rhino. Consider that carefully before you buy a large squad or two.
2. Bike Movement. Yeah, you can't jump over terrain like a Skyclaw, but your normal move is still just as fast. Even better, you've got the option to Turbo Boost! This save means your bikers are that much more likely to survive battles on planet Bowlingball Prime.
3. Biker Toughness. Holy crap, they're T5? Nope, that's Thunderwolves. Bikers are 4(5). Not that the distinction matters too much as only Attack Bikes have 2 wounds. Still, do remember Instant Death rules before you allocate that Lascannon wound to your Attack Bike.
4. Bike Bolters. Now your Blood Claws can pretend to be Grey Hunters with Bolters of their very own! They've even been given twin-linking training wheels to mitigate that BS3. With Bikes being Relentless, it's almost like a Bolt Pistol too! Just be warned that Headstrong can still hamper your shooting.
5. Attack Bike. Hooray! With their mighty BS3, I'm sure that one heavy weapon will instantly be the envy of the pack and the life of every party. (Can you tell I'm underwhelmed?) Their main advantage is as a cheap way to get another wound.
6. Squads of 3-10. Well, I guess if you took a full pack and spaced them out, you could Screen a huge slice of the board. Hmmm... (read farther below)
7. No Mark of the Wulfen option. So sub-human ferals with talons for hands can operate Bolt Pistols and Jumppacks, but not a bike. Seems fair.
8. Meltabombs. Note that everyone has to get them though. The main use of these is to make the whole pack more expensive.
Swiftclaw packs remind me of teen dating... full of mixed signals, hasty fumbling in the dark, and mistaken impressions fueled by reputable sources like internet porn sites. Bikers are a unit designed to be fast, mobile and SHOOTY. They zip around, shoot lots and only swoop in for the kill after weakening the enemy. In turn, Blood Claws are meant to be a shock assault unit that's constantly on the charge; shooting is a secondary to non-concern. The combination of the two styles is underwhelming at best. You end up with a fast moving assault unit that's isn't cost-effective for either role you've paid for. I just don't see Swiftclaws really having a good use in most armies.
Still, the keen among you will note that I said "most" armies. Where I think they can shine? Cavalry armies. Why? Because they can Screen. But aren't Fenrisian Wolves a third the cost? Yeah, but do F-Wolves have T5, a 3+ armour and the ability Turbo Boost 24" with a 3+ Invulnerable cover save? I thought not. Use your Swiftclaws to zip out fast and form your front line. Their size and squad status will give saves to most any unit behind them. This can be a critical item for Turn 1-2 where your Cavalry are humping across the field at a 6+d6" pace, especially in a Dawn of War scenario. That BS3 doesn't matter when Turbo-boosting since they can't shoot anyways. Yes, there's other issues such as competing for a Fast Attack slot with Thunderwolves, but I think the strategy is worth it for a single large unit. (Notably, this benefit extends to Infantry armies too. I just don't see it as high as those usually Shooty rather than Assaulty, have spare bodies, and/or have cover to rely on.)
So, what upgrades would I suggest? Unless you think you need an 11-man unit, start by giving most of your Attack Bikes to any friends that play White Scars or Ravenwing. They'll be of more use there as Wolves lack Attack Bike Squadrions. Then follow the same rules as for Blood Claws: don't bother with plasma, only take flamers or power weapons if your army needs it, and consider a meltagun and/or powerfist.
As to Leadership, with a Ld8 and a 3d6" Fall Back you don't want these guys running if you can help it. I would consider some form of leader a minimum requirement. A Wolf Guard is nice even if you have an IC; I'd probably give him a Power Fist, maybe a combi-melta and then call it good. A Wolf Lord or Battle Leader can be good with these guys, but still doesn't seem optiomal when a Thunderwolf Mount is just a little bit more. I like a Rune Priest for as the squad lets him get up close and personal quickly. This is mainly of effect for his Runic Weapon, but might also be nice for his Powers. But with the emphasis of this unit on rapid movement, Screening and multiple assaults... as long as you have anti-Psyker covered elsewhere, I think the Wolf Priest edges the competition out due to Preferred Enemy and Fearless.
In the final analysis: These guys aren't likely to be in any OMGWTFBBQ internetz lists, but they are a good choice in virtually any army if you know how to use them. Just make sure you include them and use them for the right reasons. They are not a shock-assault unit, but instead a speed bump or distraction. Within the right army and a touch of guile, I think they can be serious game winners.
***My original image was a dog on a unicycle with top hat, but then I remembered the atrocity that is Biker Mice from Mars. (Copyright Criterion Limited)***
(Wow, these really go faster when I'm not doing all those damned graphs... Cheers and hope you've gotten some good ideas.)