These bikes represent the latest step up in the Hinckley Thunderbird heritage that started with the 900 cc model back in 1994 as John Bloor revived the brand.In 2009, the Thunderbird became a 1600 cc parallel twin cylinder cruiser. In 2011, the line was extended to include the 1700 cc Thunderbird Storm, with the extra displacement coming from an upgraded version of the original T16 engine.The parallel twin engine configuration is “what we do” as Triumph North America CEO Greg Heichelbech explained, reflecting on the long tradition of parallel twins Triumph has going back to those designed by Edward Turner.Tradition aside, the twin powering the LT and Commander is a quantum leap from Turner’s OHV twins; with 1700 cc displacement, liquid cooling, dual counterbalancers to stanch vibration, double overhead cams, 270° firing interval and multi-port sequential electronic fuel injection, the motor is the largest production parallel twin in the world.Claimed output numbers back that up with 93 bhp at 5,400 RPM and 111 lb./ft. of torque at 3,550 RPM. A progressive throttle linkage helps make all that horsepower available to the rear wheel in a very smooth, predictable way.The bikes share six speed transmissions, wet multi-plate clutch and toothed belt final drive, twin-spine tubular steel frame, rider and pillion cast footboards, shrouded 47mm Showa forks with 120 mm of travel and five-way adjustable Showa twin rear shocks with 109 mm of travel in a progressive-rate spring configuration. Saddle height on both bikes is 27.5” and the wheelbase for each is 65.5.” Rake and trail 29.9°/133 mm on the LT and 30.1°/135 mm on the Commander.Taking rider comfort closer to home, Triumph has put a lot of effort into the seat on both models. Featuring double-layer dual density cushioning, the seat shape is wide with flared sides and lumbar support to maximize the area of rider support.Nissin four-piston fixed calipers with ABS on double 310 mm floating discs provide braking up front with a two piston Brembo floating caliper on a single 310 mm floating disk with ABS at the rear on both models.Both bikes feature 5.8 gal. (22 liter) fuel tanks with offset filler cap and tank-top instrument panels with large analog speedometer and fuel gauge and LCD twin trip meters, odometer, clock and range-to-empty indicator all scrollable from a handlebar control.There are some differences that define the character of each bike. The LT features 56 spoke wire-laced wheels, 16” x 3.5” up front mounting a 150/80 R 16 whitewall Avon tire, 16” x 5.5” mounting a 180/70 R16 whitewall to the rear.The Commander comes fitted with five-spoke cast aluminum alloy wheels, 17” x 3.5” up front mounting a 140/75 ZR17 blackwall tire, 17” x 6.0” mounting a 200/50 ZR17 75W blackwall to the rear.Both bikes feature chromed twin skin stainless steel two-into-one-into-two exhaust systems, but the silencers are not alike. The LT carries a pair of tapered tri-oval mufflers that give a touring bike look with an understated baritone rumble. The Commander, on the other hand has a pair of straight-cut “drain pipe” mufflers that deliver a somewhat more pronounced—almost rowdy—exhaust note without being obtrusive.The most notable visual difference between the LT (Light Touring) and Commander is in the provision of standard semi-rigid saddle bags, windshield and triple light configuration up front on the LT, where the Commander comes in cruiser trim—without bags and windshield and equipped with dual headlights.Of course, both bikes can be reconfigured to suit the owner with a wide range of accessories. Seating position is slightly different between the two bikes, with the Commander handlebars set up to bring the rider into slightly more forward lean than the LT. As a result of the touring gear standard on the LT, it has a bit more heft weighing in at 836 pounds (wet) compared to the Commander at 766 pounds.On the road, the Commander’s lighter weight, tire sizing and slightly different rake/trail add up to a subtle but noticeable difference in agility and responsiveness. This became evident on the narrow canyon roads northeast of San Diego.Both bikes have surprising flick-factor in the tight, blind corners of those roads, given their overall size. Each feels lighter than it is, but it is the Commander that has a slight edge in the quarter-horse agility and out-of-the corner launch speed that makes canyon carving so much fun.The LT that comes into its own on the long straight stretches of highway in the desert, where sustained highway speed driving brings the windshield and touring seating position to the fore.The bags that feature lift-out carry alongs make the “light touring” part of the package work very well. The bags aren’t lockable, but feature quick-release buckles behind the traditional looking metal buckles on the straps.Both bikes make use of all that torque very easy with roll-on power available in virtually any gear and speed; you have to really slow the bike down in top gear to get it into a situation where it has to lug—and then it really doesn’t. It just pulls like a tractor and gains speed smoothly. Indeed, the Thunderbird motor is smooth at just about any speed and operating condition.Acceleration is about as compelling as you want, depending on how much twist you give the throttle, but despite their ample power, neither bike tends to overpower the rider. The bike makes correction of minor mistakes in cornering line and braking easy. Controls are logically located and instinctive, though the tank-top instrument mounting requires the rider to take eyes off the road.Of course, having a lot of go is no good without a lot of stop and the ABS brakes deliver. They are progressive and require only light lever pressure to deliver smooth, straight stops.The seat, seat height and seating position worked well for me on both bikes, even though I’m probably a little shorter than average. Day-long riding didn’t generate any fatigue or sore spots. The seat Triumph put so much development time into works well.Its progressive support and ergonomic shape prevents the development of pressure points and allows the rider to change position on the seat more than one typically experiences with a stepped seat configuration. Of course, how well the seat fits each rider is a big factor in this, so some variation on this point is always possible.The heel-toe shifter does limit foot placement on the foot boards, but that is easily remedied, since the shifter is adjustable.Triumph has managed to offer two distinctively different bikes on a common platform; the Commander a sporty, aggressive power cruiser, and the LT a ready-for-the-road light touring bike — both with a common heritage.