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One feature of Guerrilla Gravity’s unique, U.S.-made Revved carbon frames is the front triangle’s capability to suit five unique bikes and two wheel sizes. Different forks, rear shocks and seatstays step in to make this whole magic trick possible, but there’s also one small, simple chunk of aluminum involved. Guerrilla Gravity’s modular lower headset cup happens to make Revved Carbon bikes the perfect laboratory for experimenting with mixed wheel sizes. Guerrilla Gravity bikes with 27.5-inch front wheels use an external lower cup, while those with 29-inch front wheels use an internal cup. The difference is a little over 10mm. Not enough on its own to entirely make up for the increased ride height of a 29-inch fork and front wheel, but enough to allow you to go mixed without sacrificing front travel and with only a moderate disruption to the bike’s original geometry. It’s a popular hack among Guerrilla Gravity owners, but now that they’re offering MX Rally edition Megatrail and Shred Dogg, you can go mixed-wheel out of the box.
The 165mm- or 155mm-rear-travel Megatrail MX Rally build gets a 170mm 29-inch RockShox Zeb, while the 130mm- or 140mm-rear-travel Shred Dogg gets a 150mm 29-inch Lyric. That’s the same fork travel as what is specced on these bikes’ matched-wheel 27.5-inch builds, so each ends up with a higher stack height and slacker head angle. Guerrilla Gravity didn’t want the MX Rally Builds to be tied down to the intentions of the models they’re based on, but to surpass them. Much of the motivation behind these builds came from customer feedback, (the sort of thing a small core brand like Guerrilla Gravity can pay attention to). Many Guerrilla Gravity owners who are making their own mixed-wheel builds are taking this same approach. They’re also generally running their frames in the longer-travel of the two available positions on the rear shock. Keep in mind, going full-travel-big-wheel up front does mean you end up with a slacker seat tube angle, a higher bottom bracket and a shorter reach. If I may editorialize for a moment, a 160mm fork on the Megatrail and a 140mm fork on the Shred Dogg would still leave you with a higher, slacker front end, but wouldn’t compromise as much of each bikes’ practicality. If that approach makes more sense, you could swap for a 10mm shorter aftermarket air spring in either fork to make the MX Rally Builds slightly more trail-oriented. Guerrilla Gravity has indicated that they can help you source the parts for that if that’s the route you want to go. Again, small-brand benefits.
In fact, Guerrilla Gravity lets you pick many of your parts a la carte. Although we’re, of course, dealing with the Great Availability Crisis of 2021, you can opt for the drivetrain, brakes and tires that suit your needs. The rest of the build features highlights like an e*thirteen cockpit, Bike Yoke dropper post, and, of course, a mixed-sized wheelset from Spank. Depending on your choices, the MX Rally Build starts at $5,695, just an extra $100 over the stock Rally build. Guerrilla Gravity has stated that the estimated lead times on an MX Rally Build is “4 to 5 weeks,” but that also may depend on the build you choose.
Another interesting tidbit to this is that Guerrilla Gravity is not calling these “mullet” builds. You might think that a brand with such a metal motif—from the rocker head badge to model names like Megatrail—would be all-in on the mullet. But they chose MX, and not because of the ongoing trademark battle over the word, “mullet,” but simply because Guerrilla Gravity has an eye towards the future. Marshal Olson, Guerrilla Gravity’s marketing director put it rather well. “We love mullets, but like the real thing, something else is a little easier to live with day-in-and-day-out.”
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