Home > Feature Stories

Cannondale Headquarters Tour, Part 3: Insane GT prototypes & concepts

36 Comments
Support us! Bikerumor may earn a small commission from affiliate links in this article. Learn More

If you thought the prototype and team Cannondale mountain bikes from our HQ tour were wild, wait until you see these GT full suspension concepts. Above is a working concept bike developed by the product and engineering teams for an Interbike show. This early concept led to the iT-1 bike from 2006…

This is a production sample of the 2006 GT iT-1 downhill bike. Word around the Interwebs is they only made about 200 of these for retail. But wait, let’s back up and check out some details:

The shifts are made internally, using a 7-speed planetary hub-style gear box inside the frame between the two upper gears. A single chainring drives a chain up to a second ring on the right side, which is geared before turned the ring on the left side, when then drives the chain leading back to rear hub. This reduces unsprung weight at the rear axle, which generally leads to more sensitive suspension. Check out this video to see it in action.

Click to enlarge the images and you’ll see the cable running into upper axle/gear cluster to actuate the shifts. You’ll also see a lot of superfluous decoration on the frame, which gives it a very Mad Max look.

This wasn’t i-Drive because the crank’s spindle didn’t float on the lower linkage. Since the upper pivot doesn’t use a linkage, the lower pivot has to extend backward, which means there’s chain growth, so a chain tensioner with pulley wheel keeps it tight, same as the derailleur’s cage would in a normal setup.

The drivetrain design means the brake has to be on the right side. Note the sliding dropout to adjust wheelbase, and possible chain tension, too.

And this adjustable stem. Wouldn’t wanna go downhilling with this!

To spread the word about the design and get some attention, they made this original concept back in 1997. Check out this story from Dirt for some history.

By 2004/2005, this is what it looked like…still a prototype. All that work, and very little production action to show for it, but keep in mind these were the glory years of big budget mountain bike racing and pie in the sky thinking, all of which led to the extremely dialed mountain bikes we enjoy today.

Some of that thinking also led to the i-Drive suspension that GT did use to good effect for many years (and continues to refine, though the name has changed).

This blue one was a concept bike made for Interbike tradeshow (c. 1999) out of GT’s former HQ in Santa Ana, CA. It was an XC version of the iDrive full suspension system with a single-sided swingarm, proprietary rear hub/wheel system, and center mounted rear disc brake. The concept was really ahead of its time visually and conceptually, but never went to production.

The single-sided swingarm isn’t even the craziest part of this bike, it’s the way they integrated the rear disc brake into the hub:

That’s a tiny little rotor, from the looks of it not even 140mm.

For the unfamiliar, the I-drive system used a dog bone link anchored at the base of the downtube to pull on and rotate the bottom bracket assembly inside the outer shell. That allowed them to use a simple single-pivot suspension design and put the pivot higher up, but still keep the crank’s spindle from falling too far backward.

This one’s carbon frame looked like a more traditional use of the material, particularly in comparison to the thermoplastic STS and LTS frames…

This STS DH mountain bike used carbon/thermoplastic tubes molded inside aluminum lugs. Suspension designs at the back varied depending on travel, with this longer travel model used a pull shock design, except that the part “pulling” the coil spring into compression was situated such that it was really pushing it.

Same for this prototype, except it was to prove the design before the cost of composites were added to the equation.

Drum brake for a DH bike, anyone?

The shorter travel LTS XC bike used a trunnion mount design to sandwich the shock between pivots on the seatstays.

It wasn’t all mountain bikes on the GT side. They have a big heritage in BMX, and this carbon fiber Ultra Box 2 bike was probably crazy stiff.

This track frame used a smaller front wheel, with the rear shifter on the aero extensions and the front shifter still on the downtube.

This one’s paint job almost made it too hard to look at anything else, but check out these brake levers:

Maybe it was the aging cables creating a ton of drag, but my hunch is it’s just the very, very bad design. To pull the brakes, you had to pull the tip outward (or in which ever direction you had it twisted when mounting), which meant you could very easily put a lot of unintentional input into the steering…and lose control if you weren’t on top of it.

Thanks a ton to the crew at CSG for showing us around and providing some background on their bikes!

GTbicycles.com

Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

36 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments
Greg
Greg
7 years ago

Practically zero chain growth on the first bike due to the jackshaft.
Not a track bike, a tri (or tt) bike. Track bikes don’t have gears of brakes.

Douglas
Douglas
7 years ago

“Since the upper pivot doesn’t use a linkage, the lower pivot has to extend backward, which means there’s chain growth, so a chain tensioner with pulley wheel keeps it tight, same as the derailleur’s cage would in a normal setup.”

Surely there is chain growth simply because the main pivot is not concentric to the gearbox sprocket? Nothing to do with linkages extending backwards….

ginsu
ginsu
7 years ago

Well, theoretically, there’s a way to design a four-bar linkage where the instantaneous center closely tracks the pivot point for the chain (i.e. the BB, or in this case the output for the transmission), and creates minimal, possibly zero chain growth. Most designs try to mitigate chain tension forces on the suspension as well.

By looking at the Instant Center you can easily determine chain growth and the lever arm by which chain tension forces are delivered. In this case, the IC starts very close to the sprocket, but migrates forward and down as the suspension compresses. This design will inevitably have some chain growth issues. Thus, they were forced to used that sprung black pulley device to account for the chain growth.

They could’ve used a conventional single-pivot design and they would’ve had a much simpler design, but this is a high-pivot four-bar, which has a pretty nice initial rearward-axle path on bump.

Greg
Greg
7 years ago
Reply to  ginsu

It is a linkage driven single pivot. Seatstay is the swingarm, so in this case the rearmost chainstay pivot does not make it a four bar.
Chain growth is “practically” zero with its pivot near the chain line, chain growth being the length of upper run of chain, which directly affects pedal kickback. This situation still requires a small tensioner
Total chain requirement is different, equalling zero when the pivot is concentric with the chainring (which gives you negative “chain growth” and torque driven squat).

TheKaiser
TheKaiser
7 years ago
Reply to  Greg

Everyone listen to Greg, he knows what he’s talking about.

As an aside, the pivot location of this linkage activated single pivot swingarm design will reduce the tendency to squat under power, when compared to a more traditional low-mid pivot design, due to its differing relationship to rider mass.

ginsu
ginsu
7 years ago
Reply to  Greg

You obviously don’t know what a 4-bar linkage is. There are four links comprising this design. Look closely!

There is the
1: the bike,
2: the short-arm black linkage connecting the shock (driver),
3: the ‘axle link’,
4: the upper long arm linkage.

There IS A TON of CHAIN GROWTH IN THIS DESIGN. WHY ELSE DO THEY HAVE SO MUCH CHAIN SLACK AND A SPRUNG PULLEY?

(deleted)

ginsu
ginsu
7 years ago
Reply to  ginsu

True, but that’s just the axle path. We were arguing about whether or NOT there was CHAIN GROWTH…WHICH THERE MOST DEFINITELY IS, AND THAT IS BECAUSE IT IS A 4-BAR LINKAGE!!!

The four-bar mechanism, in its simplest form, has four bar-shaped links and four turning pairs, as shown in the animation. The fixed link (the black bar) may actually be bar-shaped, but more frequently it represents the frame of a machine and in that case is usually a massive casting of irregular shape. This interesting linkage system is the building block of more complicated mechanical linkage systems. Therefore it is a fundamental concept to be learned by mechanical engineering students.

In a four-bar mechanism, one of the rotating members usually is the driver and is called the crank or driver (the red bar). The other usually is called the rocker or follower (the green bar). The floating link ( the blue bar ) that connects the crank and the rocker is called the connecting rod, and the fixed link ( the black bar ) is called the frame.

Many mechanisms can be broken down into equivalent four-bar linkages. These mechanisms have many aplications in mecanical operations. Four-bar linkages are considered one of the fundamental mechanisms.

ginsu
ginsu
7 years ago
Reply to  ginsu

I will concede that the suspension is not arranged like a TYPICAL 4-BAR LINKAGE, as they did not put the axle on the ‘floating link’…regardless when a design has 4 LINKS and 4 PIVOTS…IN MECHANICAL ENGINEERING TERMS IT IS STILL A 4-BAR LINKAGE.

Yes, technically, this does not have IC migration the way it is arranged (my initial mistake)…THIS DESIGN STILL HAS A TON OF CHAIN GROWTH BECAUSE THE PIVOT IS NOT CONCENTRIC WITH THE OUTPUT SPROCKET!

ginsu
ginsu
7 years ago
Reply to  ginsu

I guess the real issue here is that you guys don’t know your terminology and I’ve been stuck in textbooks for a long time. Technically, on our own terms we both have merit.

So I’m sorry if I insulted anybody, but honestly, arguing with laypeople is very difficult because they simply don’t understand the nomenclature of a professional engineer.

Anyway, I just thought I would clear that up for posterity.

Amp
Amp
7 years ago
Reply to  ginsu

Sorry Ginsu, Greg is correct. I think you are thinking its a 4-bar because there is a pivot point in the chainstay but you have to look at this one upside down. On every other 4-bar you’ve ever seen there is a link connected to the seatstay that drives the shock but this one has the link driving the shock on the chainstay instead.

Sure, it has a rearward axle path because the main pivot is so high, but it won’t have massive chain growth because the single pivot is reasonably close the the axis of the “gearbox” where the chain is coming from.

If this bike used a regular crank where the chain heads to the rear wheel from around the crank arms but they still left that main pivot that high, thats where you get massive chain growth. A derailleur cage has the ability to take up huge amounts of chain slack compared to a sprung pulley. This one doesn’t have a huge amount so the sprung pulley worked fine.

Interesting bike, really makes me curious about modern gearbox bikes and the possibilities.

ol shel
ol shel
7 years ago
Reply to  Amp

Additionally, some true 4-bar designs have little or no advantage over faux-bars. 4-bars with layed-down stays and nearly vertical upper links (hanging down from TT or reaching up from the ST (Stumpjumper) don’t keep the ‘upright link’ (seatstay) upright. When the upright link rotates along with the chainstay, the brake isolation advantages are reduced or eliminated.

For DH, almost any rear suspension design works, as shown by the variety of bikes that win. The lower unsprung weight of a gearbox bike might be nice, but it’s likely to be offset offset by the weight and drag on most courses.

knarc
knarc
7 years ago

Cannondale and GT are the same?

Beat_the_trail
Beat_the_trail
7 years ago
Reply to  knarc

Well, you see Knarc, a long time ago, GT was one of the largest and most respected domestic manufacturers, building nearly everything from some factories in either California or further up the coast in Oregon. After Mr. Turner got bought out, the company was run into the ground by poor management and was eventually bought out and production was moved overseas. No GTs are essentially glorified Walmart bikes.

Cannondale had a similar fate, except their undoing was because of a terrible decision to start building ATVs and Dirt bikes using an in house designed and manufactured engine, which was crap, and the warranty drove them into bankruptcy. Plus their dirt bikes regarded as being the worst possible offering at the time.

To be fair, everything Cannondale has ever produced would likely be best suited to being sold in a Walmart. You don’t earn the nickname “crack-n-fail” easily.

GT however was once one of the finest marques available. Especially in the BMX world.

TheKaiser
TheKaiser
7 years ago
Reply to  Beat_the_trail

Harsh as h3!! but there is some truth to these statements. The generations of C-dales that Peter Denk designed have had some pretty sweet models though. Road bikes across the board, and MTB contingent on you not minding their proprietary “systems” stuff.

JNH
JNH
7 years ago
Reply to  Beat_the_trail

That’s a little harsh on old Crackenphail. The Prophet was one of the best all around bikes produced in the 2000s. Then there was the Gemini, Gracia and Judge downhill bikes that were also amazing. The lighterweight bikes were somewhat more deserving of the reputation, I remember seeing a lot of cracked F-series hardtails over the years. I dearly loved my Prophet MX, 160mm travel, iscg tabs, through axle, 30lbs in 2006. Kept it until 2012 when the inevitable big crash happened.

Old fut
Old fut
7 years ago
Reply to  Beat_the_trail

Ahahahahaha. Made me laugh. Have to say, despite having owned a gt bmx, a gt hardtail and a CAAD 9, not my favorite two manufacturers at all.

duder
duder
7 years ago
Reply to  Beat_the_trail

Cannondale has done some great stuff too. Headshock was miles ahead in the days of the Judy and Mach3. Still awful compared to today’s offerings, but great compared to competitors at the time.

They were among the first companies to spec 2x cranks via their Coda brand. Also among the first to spec disc brakes on production MTBs, and later among the first to standardize on discs across their entire line. They created BB30.

They got the “crack and fail” name because they started early with alloy, but they had it figured out by the mid 90s when others were just starting with alloy. They had some of the first FS bikes that were actually rideable and you might legitimately consider over a hardtail.

They sponsored some of the most iconic XC and DH athletes, really pushing the sport forward.

I’ll always have a soft spot for them. It’s a shame the moto thing killed them. I’d love to see what they could have come up with today if they had the same ability for wild engineering experiments as they did back then.

ol shel
ol shel
7 years ago
Reply to  Beat_the_trail

Their mistake was not producing the all-billet mtb and the rollerblade-wheeled road bike.

FiftyThree11
FiftyThree11
7 years ago
Reply to  knarc

They are both owned by the same parent company

ignis
ignis
7 years ago

thank you for the article

very interesting

knarc
knarc
7 years ago

Yes, i met GT from the bmx world and to be honest i had heard very good reviews. What happen now with them? I mean, now Cannondale is one of the biggest brand especially in innovation but GT? They make their bikes in US? Who is now owner?

Beat_the_trail
Beat_the_trail
7 years ago
Reply to  knarc
bikerhp
bikerhp
7 years ago

Glad GT still has these bikes after being sold and moving so many times. From CA. to Boulder to Madison to CT. It is amazing these bikes are still around. Also GT history goes a little like this. GT goes public. Richard Long (GT’s CEO and CO-Founder) dies in a motorcycle crash. GT starts to bleed cash and is on the verge of bankruptcy. Schwinn Bicycles buys GT and takes on GT money problems. A couple years later Schwinn starts to move some of the GT operations to Boulder, to save money. Schwinn-GT could never dig out of GT’s old money problems. They both file for bankruptcy. Pacific Cycle (owner of Mongoose, Roadmaster, and Pacific brands) buys Schwinn-GT out of bankruptcy. Schwinn-GT move to Madison, WI and become part of Pacific Cycle. Pacific Cycle is sold to Dorel. Dorel buys Cannondale. The “good” bikes (GT and Schwinn’s for bike shops) are then move to CT to be in the Cannondale office. I believe Schwinn IBD are now designed in Madison again but GT and Cannondale are all designed in CT. None of the bikes are made in the USA unless you order a Schwinn Paramount (From Waterford Bicycles). Cannondale, Schwinn, GT Mongoose, Iron Horse and Roadmasters are all owned by Dorel.

knarc
knarc
7 years ago
Reply to  bikerhp

This looks a very big company. I wonder why produce their bikes in asia? Surely the cost is lower but i think the qualty of production, especially in high end bikes, can compensate this cost.

Vincent
Vincent
7 years ago

Ha the single sided i-drive ! I remember it from the days i was lusting over magazines.
That’s a very nice piece, thanks a lot for featuring one here !

Dockboy
Dockboy
7 years ago

Nice to see an old LTS. GT is rare in that they’ve used basically 3 suspension designs since the early 90s. The RTS was the first, not mentioned here, but very similar to the IT-1 without the gearbox and idling system. After that, LTS carried them to the end of the 90s with its high profile 4 bar linkage, nor they’re on i-Drive and its variants for what now, 15 years or more? It may not be FSR, but they have certainly done well with their platforms.

Jesse Edwards
Jesse Edwards
7 years ago

It’s hard to believe we’ll look at today’s bikes and think they look that awful.

ascarlarkinyar
ascarlarkinyar
7 years ago

So sad that cannondale’s innovation has ended. All they are able to do these days is re copy past efforts. Barely.

Andrew Spaulding
7 years ago
Reply to  ascarlarkinyar

Ignorance must be bliss. At what point do you consider past efforts? The pull shock? Last year’s Slate?

knarc
knarc
7 years ago

pull shock isn’t cannondale’s innovation. I saw this system first in scott. https://www.bicyclebluebook.com/searchlistingdetail.aspx?id=3048810.
Cannondale took the founder of this system from scott.

Motarded450
Motarded450
7 years ago
Reply to  knarc

Pull Shocks were used on Schwinns in the late 90’s

bikerhp
bikerhp
7 years ago

Links to websites for brands owned by Dorel:
Dorel Sports
caloi.com
cannondale.com
chargebikes.com
dorelsports.com
fabric.cc
gtbicycles.com
gurucycling.com
kidtraxtoys.com
mongoose.com
schwinnbikes.com
sombriocartel.com
sugoi.com

Divisions:
Cycling Sports Group (CSG)
Pacific Cycle
Caloi

Product Range:
Premium/mass market bicycles
Branded performance apparel
Jogging strollers
Ride-on toys

Mike
Mike
7 years ago

The “STS DH bike” is actually a production Lobo. Nothing prototype at all about that bike.

Alex
Alex
7 years ago

For a good read on the sad end to GT check this out:

http://redkiteprayer.com/2016/07/get-it-done-remembering-richard-long/

Wonder how things would have turned out had Richard Long not passed away. GT was always such a great brand. Glad to see that the past few years have seen the brand on the up. Kudos to the team over in Wilton helping keep the fire going.

Brent Coe
Brent Coe
7 years ago

Profile Speed Modulators on that last bike. I remember when Nashbar had them on closeout back in the good ol (pre-performance) days.

Kevin Sande
6 years ago

Have as many prototype one offs as the GT HQ here….www.facebook.com/SeeingisBelievingGTMuseum

Subscribe Now

Sign up to receive BikeRumor content direct to your inbox.