Tuesday, May 18, 1999
I had my first look at GT's I-Drive last September at Interbike in Las Vegas. Unfortunately, while I could look, touch, ooh and ah, I couldn't ride! Ever since then I've been bugging GT to let me climb in the saddle and see if the I-Drive lives up to all the hype. I finally hooked up with them at a race in California.
After two days of pedaling around the Leguna Seca cross-country race course my answer is an unqualified yes. And no.
Right from the beginning of full suspension bikes engineers have been trying to figure out a way to kill pedal induced "bio-pacing." That herky-jerky hobbyhorse effect that occurs when pedaling a bike with an active suspension system. GT claims they have found a way. In fact, they claim "the I-Drive system is nothing short of a revolution for mountain bikes."
Without a doubt, the I-Drive annihilates any pogoing effects that you'll feel on typical full suspension bike. The ride is smoother than glass. And it should be with 4.6 inches of travel. However, it's more than just the amount of travel that makes the I-Drive so smooth.
How do they do it? Essentially, the position of the I-Drive's bottom bracket never moves. The suspension, or eccentric as GT calls it, moves around the bottom bracket much like a threaded head set works. The I-Drive however, is turned on its side and much beefier than a normal head set. But to say that the I-Drive is just a headset laid on its side isn't saying enough.
The result is what's really important here. Because the eccentric moves separately from the bottom bracket, the distance between the bottom bracket and the saddle never changes. Moreover, the distance between the rear hub and the bottom bracket doesn't change either. The consistent distances between all these crucial point's means more efficient pedal strokes. Which means all of your energy is transferred to the rear wheel.
The eccentric is connected to the front triangle's down tube by a small aluminum rod GT calls the dog bone. Shaped like a dog bone I asked GT about the part because it looks too small and fragile to hold up under big loads. Apparently it doesn't have to. The bone is a relay arm and serves mainly to force the eccentric to rotate around the bottom bracket. OK, next question...
The eccentric looks more exposed than a flasher with his trench coat open. There are more nooks, cracks and crannies in there than you'd find on Roseanne Barr. What happens to all the mud, grime and grit? GT built in a small window that allows sludge to drain out but what about thick, slimy, sticky, clay ridden goop. Won't this foul the works?
Nope says GT. Besides the fact that there are only two pivot points in the entire system, the big ball bearing the eccentric rotates on is sealed tight. We are talking low maintenance. Simply squirt a hose at it and watch the gunk drain away. It is that simple. As a test rider I felt it my duty to run the bike through the deepest mud I could find at Leguna Seca and make sure this was the case. Fortunately, after four days of rain I found several bogs to play in. All I did was get wet and dirty while the I-Drive kept right on going like the Energizer Bunny.
Which brings me to the best part of this review. How does it ride man?! Out on the trail it rocks. If you're headed downhill. It screams while descending. Let me put it to you this way. Leguna Seca's single track is like velvet. Problem is however, during a race there aren't too many places to pass because the trail is so narrow. Get off the trail and you're riding through lumpy, gopher hole infested, rocks-hiding-in-the-grass terrain. Still, passing on the outside was easy! I was amazed at how many hits, big and small, the I-Drive could handle. Literally, I found myself passing riders at will. As long as I was headed down.
The second I hit the flats or began to climb, all the ground I had chewed up was lost as other riders with lighter bikes easily caught me. Why? At 27 pounds the I-Drive is heavy. Most of the weight is located near the bottom bracket giving you a low center of gravity. This makes maneuvering the bike through tight turns and over obstacles almost effortless... so long as you have gravity on your side. Climbing on the other hand, is simply a chore on the I-Drive.
Which is why I don't understand why GT bills the bike as a cross-country steed. Yeah, most of the I-Drive models are set up with a Rock Shox SID's which says cross-country. While the I-Drive is an awesome ride I can't say I'd choose it for my cross-country bike. Especially when racing. Even at the amateur level. It feels more like a free ride bike to me. Nothing wrong with this. After a few short miles I felt completely confident in the I-Drive's ability to charge through big, bad and ugly terrain. But why not be proud of who you really are? Shoot... I could have the entire free ride concept wrong. But for me, 27 pounds is too heavy if I am out for a cross-country ride. On the other hand, if you are willing to carry the weight in exchange for a baby's butt smooth suspension you can't go wrong with the I-Drive.
In GT's defense, the carbon fiber version of the XCR, the STS weighs in at 24.5 pounds even though the carbon fiber front triangle is a half-pound heavier than the all Easton Aluminum models. GT achieves the lighter weight with a big upgrade in components from the XCR 1000 to the STS. Which leads me to believe the rumors I hear about a race model due out later this summer. GT was evasive about the new model but did agree with me that it will be easy for them to decrease the weight of the XCR 1000. I can't wait to climb into the saddle of this bike!
Is the I-Drive the most important advance in suspension ever? It might be... for now. The bike industry being what it is however, I am sure we'll be seeing and riding more cool suspension bikes in the future.
The I-Drive is available in six different models ranging in price from $1,000 to $4,350.