By Vernon Felton
GT full-suspension bikes have been based on i-Drive—the company's unique independent drivetrain patent—for almost 15 years. In the bike business, that's an eternity. Thus it was big news this past summer with GT showed off their 2014 Force and Sensor models—neither of which sport i-Drive suspension. Or, at least, neither of which seemed to rock i-Drive.
GT is calling their updated suspension design Angle Optimized Suspension (or "A.O.S.") and while it looks a bit different than what you've seen on GTs of the past, it has a good deal in common with both i-Drive and FreeDrive (the Mongoose spin on the i-Drive patent).
What exactly sets the new GT Force and Sensor bikes apart from past GT models? Why did GT decide to change things up this year? What does that actually mean out on the trail? I gave Todd Seplavy, GT's director of product management, a call to get the answers. I also pulled this new GT Force out of its box and took it for its maiden voyage. Here's the inside story on the new GTs and some first impressions of their new enduro/all-mountain machine.
BIKE: I'm looking at the new bike and it seems like I'm looking at a really well-executed Mongoose FreeDrive bike. I guess that's not a huge surprise since FreeDrive and i-Drive were related designs, but the A.O.S. design looks a lot like a cleaner, simpler version of FreeDrive—am I missing the point here?
Todd Seplavy: Yes, no and maybe a little bit. First off, i-Drive—GT's independent drivetrain design—goes back a long ways. Second, there are lots of different ways to skin a cat. If you remember, i-Drive started out as that giant, Folgers Coffee can-sized bottom bracket eccentric. It had its downsides, such as the pinner bearings. For its time, though, it was an engineering work of art. Move forward a bit and you get the next generation of i-Drive [IDXC], which sort of moved all the i-Drive components outboard of the bottom bracket. You had other manufacturers like Maverick and Klein (both of which eventually licensed the design from GT) independently making bikes on the same basic floating drivetrain principle. Then going forward from there, you have more refined versions of i-Drive [i-Drive 4 and 5] as well as the FreeDrive system, which people know from Mongoose. All these designs looked different, but they were always using iterations of the independent drivetrain patent—they just had different goals—whether it was a performance goal or a price-point goals. A.O.S. is the next step of that evolution.
BIKE: So, what makes A.O.S. different from those previous designs—particularly FreeDrive?
TS: Okay, so the new bikes still have the independent drivetrain courtesy of the new PathLink. That's obvious. One of the less obvious things, however, that really sets the new design apart from FreeDrive and previous iterations of i-Drive is that chainstay pivot—that's sort of the secret in the sauce element of the new design that really improves the bike's climbing and braking performance. That [pivot] may seem like a small thing, but little variations can make immense differences. It's nailing down those seemingly small details that took the bulk of the time we were developing the new system.
BIKE: Let's talk more about the new chainstay pivot–What were your trying to achieve with it? What on-the-trail riding traits were you trying to improve on?
TS: Well, we started the re-design project by riding a lot of bikes—both different competitors' bikes as well as our own—and all the while, we just kept asking ourselves, 'What do we like about these bikes and what don't we like?'
One of the things we kept coming back to when we rode GT bikes was that, damn, we really do like the overall pedaling traits of our bikes—they were really good at climbing. But when we started to tweak that last iteration, we found out we could either make the bike killer on the downhills, a la the Fury, or we can make it go great up a hill. But when we got into that middle ground, which everyone likes to do, then we had a bike that could be better… so we went back and started out with a list of things we wanted to achieve.
BIKE: What sorts of things were on that list?
TS: We wanted a lower center of mass on the bike. We wanted to improve the suspension tuneability through the range of travel, which is something that really came out of the feedback we were getting from pros like Dan Atherton who can push the bikes to limits that most of us can never reach. And we wanted the bike to be stiffer.
We found we could do all those things better with the chainstay pivot—particularly on the braking side of things. If you are going to descend well, you have to have good brakes.
BIKE: Are you saying that there was some brake jack with the previous design—some stiffening up of the suspension under hard braking?
TS: Yeah. Well, it wasn't the kind of brake jack that was really noticeable, like on old school bikes, but there was a little bit of stiffening. There was also some changing of mass issues. Like if you moved your center of mass way forward or way back on the bike, you'd start to notice some abrupt changes in the handling. I mean, this wasn't feedback that we were getting from most riders, but it was something we were hearing from top guys like Dan Atherton who are pushing the bikes to their outer limits and are super in tune with their bikes.
BIKE: It sounds like you guys had a pretty long laundry list of things you wanted to improve.
TS: We had the opportunity to really start fresh. We had a new team of engineers that we were working with—including Peter Denk, who worked with Cannondale on the Jekyll. When we moved across the country and took up shop with Cannondale, our in-house engineering staff really grew. I'm not going to say this re-design was easy. We pulled our hair out for a while. We went through several different iterations of the bike that you see here, and those really taught us a lot.
BIKE: How long did that process take?
TS: It took about three years—start to finish. This wasn't like we went to Taiwan and pointed to a frame on a wall and said, 'Give us that one.' This is the result of a lot of pride and people involved and a whole lot of man hours. A lot of design time and testing went into this bike.
BIKE: I was reading on the GT website that A.O.S. eliminates chain growth, but really it has to be doing something more like "optimizing" chain growth since some chain growth is needed to give the bike a degree of anti-squat that'll keep it from bobbing under pedaling.
TS: Yeah, it's not about eliminating chain growth. but optimizing it. There is such a limited amount of chain growth compared to the previous generation of i-Drive and that version had really very little chain growth itself… Pedal feedback was never a problem with the past iterations.
BIKE: Most of the spec is spot on with current trends for all-mountain bikes—wide bar, short stem, wide rims, beefy tires. The one thing that sticks out as a bit unusual is the triple chainring crankset. Are you spec'ing triples because your dealers are reporting that riders here in the states are still demanding triples? Is it because GT is big in Europe and triples are still hot over there? I'm curious as to the reasoning, given that so much crankset spec is either double or 1X now.
TS: It's all of the above. I'm not going to play the 'We're big in Japan!' card, but the bike is a global offering and that means it has to work for people everywhere. The component spec has to be versatile. We've been spec'ing a lot of doubles on some of our past models and we've been hearing from dealers that they have a lot of customers, particularly guys living in places with big ass mountains, like the alps or certain places in Asia or South America and those riders are like, 'Hey, guys, I need a teeny gear to push up these hills.' So, bottom line, yeah, I rolled the dice on triples and maybe I'm getting blasted a little by magazine editors, but we listened to the guys in the bike shops. Time will tell.
Plus, the cool thing with having a triple is that if someone wants a triple, they're all set. If they want to go with a double and a bash, they can do that. If they want to go single-ring, they can do that too. If you buy a dedicated 1x bike, you are kind of stuck with 1X. If you buy a 2X bike without a bashring, you are kind of stuck with a double. So having the triple does open up your options a bit. Yeah, you might have to buy a bash or a new single ring, but you can at least get there from here. It's not like you are locked into just one kind of crankset.
BIKE: One thing that did strike me about the bike was the through-axle pivots in the center of the bike—that extra stiffness in the center of the frame—it has a very [Cannondale] Jekyll flavor to it. Was that something you were aiming for with this design?
TS: Absolutely. With the older bikes, if you were really pushing them in a berm, you might feel the tire buzz on the seatstay. We knew, right out of the gates, that improving stiffness was a big priority for us. The double row bearings on the chainstays, the super-stout design of the PathLink and the oversized seatstays—it all adds up to a really stiff and confident frame.
I've always liked bikes that have that kind of stiffness to them. You take that center stiffness and you combine it with that low center of mass and some progressive frame geometry, and you start to get a bike that you can have those ‘Oh, shit!’ moments on, but when you're saying ‘Oh, shit!’, you're also smiling.
BIKE: You mentioned "progressive geometry". Why is that important?
TS: This isn't just a GT thing, but the shift to a more progressive geometry that we're seeing out there—more bikes with longer front ends, shorter rear ends, low bottom brackets and slack geometry—is a change for the better. It can do great things for the Average Joe rider and their ability to go fast.
At one point in time the bulk of the bike industry thought that this kind of really progressive geometry was really only suited to elite, crazy downhill racer guys, when the truth is that the average rider can really take advantage of these bikes that are long, low and slack—on your everyday rides. It's all about being able to ride faster and have more fun.
THE FIRST RIDE
The first ride is just that—a chance to dip your toe in the water and figure out which is end is which. In a sense, I had a head start on the process as I'd tested the 2014 GT Sensor in Sedona [see that review here]. The Force has a lot of the same attributes—the bike feels stable and planted at any speed. The low center of mass is a huge part of that. To put it in simple terms—the guts of the frame are all hanging down there by the bottom bracket and that prevents the bike from feeling akward or top heavy. It's a very good thing.
Like the Sensor, the Force boasts insane levels of traction under pedaling loads. All bike designs involve some degree of trade off—you give up one thing to gain another. It's the no-free-lunch maxim of engineering and in terms of full suspension designs, it usually means that bikes which pedal well (that is to say,, those that accelerate without a lot of bobbing, monkey motion) usually sacrifice some small bump compliance and traction under pedaling loads. The GT doesn't accelerate with the jaw-dropping briskness of, for instance, a Santa Cruz VPP-equipped bike, but it moves on out quite well and the rear wheel boasts unreal levels of traction over rocks and roots.
So the Force is a lot like the Sensor. But better. It may be premature to say this, but I think the Force is closer to my ideal than the Sensor. It's not just the extra inch of travel (six inches instead of five) and the slacker geometry. We found ourselves loving the Sensor frame and grumbling over some of the parts spec. The Force, however, is ideally kitted out for the job. Nice, wide (760-mm) bars, a short (60-mm) stem, fat (2.4-inch) Continental Trail King tires, WTB ST i23 wheelset….there's not a lot I'd change here.
Price? Okay, this thing ain't cheap and, at $5,210, I imagine someone out there has to be wondering why the hell there is a Shimano SLX crank and shifters on this bike. True, bikes at this price range often have flashier bits in those spots, but the big ticket items on the Force Carbon Expert (RockShox Revelation RL fork, WTB i23 wheelset, Fox CTD rear shock and KindShock LEV Integra dropper post) are all winners. What's more, the frame is completely carbon—front and rear triangles alike. A lot of bikes in this price range have only carbon front triangles. It’s worth bearing in mind…
Still too damn pricey for you? At this point the Force is only available in carbon, but if history is any indication, the odds are good that GT will eventually roll out less expensive aluminum versions of the Force (just as they've already done with the Sensor) .
These, of course, are just first impressions. Look for an in-depth, long-term review of the Force in the future.