Note: In response to customer feedback, Hammerhead have rechristened the Thumper the 120X. Get the scoop here!
Hammerhead Bikes’ isn’t a ride for the shy. At least in our neck of the woods, the full-suspension trail 29er, with its nice details, sexy build, and sparkly black cherry paint attracts a lot of questions.
What is it?
A 140mm front/120mm rear trail bike.
Who makes it?
The newly reborn Hammerhead Bikes out of Tulsa, OK.
Is it awesome?
You’ll have to jump the break to find out!
Known from its birth in 2009 until last fall as 918XC (after Tulsa’s area code), the physical and online shop that gave birth to the Thumper have long been 29er boosters. 
When 918XC merged with Austin’s Hammerhead Bikes, their intent was to remain true to the brand that once sold private labeled, long (for the time) travel 100mm Titus Racer Xs- a progenitor of the modern trail bike. The Thumper is the result.
Made in Taiwan of 6061 aluminum, the Thumper uses a similar Horst Link-enabled four-bar linkage to its predecessor, something made possible by the expiration of the patent Specialized purchased from its namesake Horst Leitner ages ago. The design is brought up to date with a tapered, AngleSet compatible head tube, 142x12mm Maxle thru axle rear, native post mount rear brake mounts, ISCG tabs, dropper hose routing, and a high direct mount front derailleur. Cartridge bearings throughout and an up-to-date Kashima-coated Fox CTD float rear shock keep things supple. All this for $1,500 for the frame ($1,815 with a 31.6mm RockShox Reverb dropper post), $5,299 as tested.
Our size large frame has a rangy 620mm (24.4in) top tube and shares its 17.5in chainstays and 68 degree head angle with the other three sizes (S-XL). A bare medium frame is said to come in at under 7lb and our complete trail-ready build hit the trail at almost exactly 30lb once 1.5lb of pedals, sealant, and bottle cage were added. After the well-executed frame, it’s the build that signals the Hammerhead team’s trail riding experience. 
From an XO drivetrain and XO trail brakes to the 140mm RockShox Revelation 29er fork and Reverb dropper to the sensible 24-36 double crankset and wide Truvativ bars and a swank Reynolds carbon fiber wheelset, our test bike’s build leave nothing to be desired.
On the trail, the Thumper is one planted, determined ride. Largely unflapplable, the rear suspension is supple without ever feeling boggy. Small-bump performance is excellent but doesn’t come at expense of efficiency, even with the CTD shock in its most open “Descend” setting. For general trail riding, setting the “Trail” mode to its lightest compression seems to work best- allowing the suspension to maintain traction on loose and technical climbs without interfering excessively when things get rough. On long or nasty descents, a quick flick to the “Descend” position lets the bike handle all manner of rough stuff- up until the 120mm travel is consumed.
Hammerhead should be proud of the Thumper’s suspension tune. There are plenty of bikes on the market from bigger brands that don’t balance small-bump capability, big-bump composure, and pedaling efficiency nearly as well. Frame stiffness is impressive and the weight is very reasonable for the bike’s intended use- especially given its price.
With its 30lb trail weight, the Thumper will never be described as sprightly- though it does pedal lighter than the scale would suggest. It takes a good amount of speed (and commitment) to really work the bike, though. Up until that point, the Thumper seems happiest when left to handle rough terrain head-on and without much rider interference. A very short stem (something in the 60-70mm range) does make line changes easier at climbing’s expense- but the Thumper never quite feels playful. The Hammerhead’s planted, steamroller feel will appeal to existing 29er fans- but probably won’t sell many 26in holdouts or 650b converts. For anyone looking for a rough and ready 29er trail bike, the Thumper has some of the best big-wheel rear suspension I’ve ridden at a price that would be hard to beat.
marc
