GT Sanction Pro Frame

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Review by Jeff Brines // Photos by Patrick Nelson and Brandon Turman

I dig any machine that is really good at what it was designed to do. Perhaps my most favorite purpose built machine is the Group B class of rally cars. As opposed to most rally cars, these cars were not tuned-up sedans but purpose-built from the ground up and their performance is still talked about some 29 years after their demise.

When GT introduced the Sanction Pro I drew a parallel to Group B. Many bikes raced in the EWS are long legged trail bikes that are tuned for such application, sort of like an AWD off-the-lot sedan that is modded to compete in rallies. Not the Sanction Pro. Like those Group B monsters, this bike was built from the ground up to crush it at the top level of the sport. It wasn’t meant to noodle around mellow single track. It wasn’t built to be help riders destroy their personal bests on climbs. It certainly wasn’t meant to go get groceries with… it was meant to conquer the top step of the EWS podium. So how does it perform? Read on to find out.

GT Sanction Pro Frame Highlights

• Frame: COR Enduro Design, 6069-T6 Alloy 650b Frame, 160mm Travel Independent Drivetrain Suspension System w/Forged Linkage, Pivots, 1.5" Head Tube, and 12x142mm Thru Axle Dropouts
• Rear Shock: FOX Float X CTD Remote Kashima, 8.5"x2.5" Air Shock, w/ Rebound & Remote Lockout
• 12x142mm Maxle thru-axle included
• Seat Clamp: All Terra Alloy QR, 34.9mm
• Sizes: S, M, L, XL
• Colors: Matte Black
• MSRP: $2,170 USD

Initial Impressions and Build

To the untrained eye the Sanction Pro looks to like a scaled down version of GT’s World Cup downhill bike, the Fury. Both bikes share similar shock placement, wheel size, “Independent Drivetrain” (the most recent iteration of I-Drive), a triangulated rear end held together by a 12mm bolt on through axle, and both bikes are long. Don’t be fooled however. Besides aesthetics, the bike has very little in common with the Fury. The pivot placement was optimized for Enduro racing (a bit more sprightly than the Fury) and travel, geometry and weight were altered specifically for this bike’s purpose.

My particular frame came in at just over 7 pounds, which is on par for a frame built for this purpose. Full builds around 30lbs are very reasonable depending on the depth of your pockets and tire choice. Assembling the complete bike (GT offers the bike as frame only in the US) went fairly well, apart from two things. One, be sure your dropper post does not contact the shock. In my case, a Stealth Reverb ended up being slightly too long for the job when considering the attachment that also connects to the bottom of the post. Second, the bike utilizes a 180mm post mount rear brake mount. This is fine, unless you want to run 203 rotors like me! Though there are adaptors available for this purpose, they can be a pain to snag. I ended up using a 160-180 adaptor and shimming the additional 3mms. Cable routing in general was clean and straightforward. No silly internal routing or cables in precarious places, with the exception of the dropper post.

For reference, here are the main parts selected for this build:

• Fork: Fox 36 RC2 160mm - Fit the bike well though I'd like to see a bump in travel to 170 (or even 180) to keep up with the rear end.
• Wheels: Light Bicycle wide carbon rims laced to Hope hubs. These are stiff which coupled with the frame stiffness had me wondering just how hard I could smash corners.
• Drivetrain: SRAM XX1. The only bummer with this drivetrain was a creak from the rear derailleur that drove me absolutely nuts and was anything but easy to isolate (turned out to be the relatively common noisy clutch issue). Otherwise performance was as advertised.
• Dropper post: KS Lev 150mm. For this frame it may be the best choice, depending on how much seatpost you run "in" the frame some riders may not be able to run a Stealth Reverb for example.
• Crankset: Race Face Turbine. Dollar for dollar this is still one of the lightest, most durable and best performing cranksets out there. A true Vital 5-star item.

The bike was set up 1x11 driven by a 34 tooth chainring, both for personal preference reasons and also because a 1x transmission is the only solution available for this bike. Also worth noting is that the bike does have ISCG tabs for further chain retention and does not have a water bottle mount, a feature we’d like GT to include in the future.

Since this is a frame review, I immediately pulled the shock and inspected the linkage. Though the oversized main pivot provided smooth, effortless travel there was a bit of stickiness which I attributed attributed to the bushings within the floating bottom bracket dogbone. Although perhaps not noticeable when riding, there was a bit of friction in the system compared to other 100% bearing-driven linkage systems.

GT has been utilizing their I-Drive system in one iteration or another for over 15 years. Though this system is dubbed ‘Independent Drivetrain’ the idea is to utilize a floating bottom bracket that moves back in tandem with the rearward trajectory of the axle to reduce chain growth. When cycling the suspension it is impressive just how little chain growth there is considering the pivot placement is higher than many other bikes out there, allowing this slightly-more rearward trajectory.

Once built the first thing that caught my eye was the bike’s length. At 6’2” I typically go for XL bikes. This was the first time in years I’ve sprung for a Large and guess what? At a wheelbase of 48” it is still the longest bike I’ve ever owned.

On The Trail

Climbing & Pedaling
It’s no secret a number of enduro stages must be ascended the old fashioned way – by human power. When the trail pointed uphill, I often found myself utilizing the factory-included bar mounted Float-X CTD adjust. Though it could have been my shock, the bar mounted lever did not fully lockout the shock but instead firmed up the compression damping considerably. When in the firmest position, the bike ascended reasonably well. It didn’t want to jump up the hill but certainly didn’t have me walking any sections on the ups either. On extended climbs it felt marginally less efficient than other bikes in its class though this could have been my over worked late season legs too. A deal breaker? Not for me, but if pedaling performance is number one on your list you are likely looking at less travel to begin with.

In rougher and more technical sections of a climb, the bike’s rear end tracked well with the only big drawback being the bike’s low bottom bracket that left me crunching pedals more frequently than I otherwise would. The floating BB linkage system did an admirable job of keeping things active while not feeling like the bike was bobbing excessively – even wide open, though in certain gear ratios the bike did feel quite sluggish while sprinting or climbing. The Sanction Pro’s long top tube, slack headtube and long wheelbase were not meant to dominate tight technical climbs. A tradeoff indeed but with adjustments I found myself “dealing” with it just fine. I wasn’t walking more or less than with any other bike I’ve thrown a leg over lately.

Turning to the anti-squat numbers, the story became apparent. When utilizing a 32 tooth chainring, the anti squat properties look okay when geared low (42 or 36 tooth cog on the cassette) with values around 90% which would explain the reasonable pedaling performance (100% is ideal). However, when geared higher with a 36-tooth ring the numbers are less than ideal at around 70%. Obviously a bike’s pedaling performance isn’t just attributable to one thing. Having anti-squat numbers of 100% while descending can be less than ideal too as pedal kickback can be overly noticeable leading to less than desirable performance. We’ll just leave the nerdery there and say: the Sanction pedals okay but not awesome.

At the end of the day, the big question I kept coming back to in my head is “would I take this bike on an all day epic kind of ride?” as most riders who purchase a bike like the Sanction Pro will look for it to do everything. The answer is yes – sorta. If your thing is all day rides and you happen to do one or two enduro races a year there are better, more efficient bikes out there. If however you care most about downhill performance (carrying speed) this bike will more than suffice for those 5+ hour rides, just as long as you manage expectations and have the legs to push it. To add, it’s among the only “trail” style bikes I’d willingly ride full on DH stuff aboard… but more on that below.

Descending
When the trail points down this bike comes alive. Well, almost... If the trail is on the mellow side of things, the Sanction Pro can leave the rider bored. With a higher than average main pivot point, 165mm of very active travel and a long wheelbase the bike wasn’t the most playful on the local XC loop. But this would be like saying that my race car was boring going to get groceries with.

To really get to know the Sanction Pro things need to be a bit more interesting. The Pro is most at home on trails that you feel comfortable riding while donning goggles and a full face. I’ve never been on a 150 to 170mm bike that encourages such stupid decision making.

Frame Stiffness
In rougher high-speed terrain the first thing I noticed about the bike was how stout it is. With a true 12mm pinch bolt-secured through axle and a triangulated swingarm driven by one of the largest main pivots I’ve ever seen on a mountain bike, the Sanction Pro is one of the most flex-free frames I’ve ridden. Combine this with the bike's long wheelbase and low bottom bracket and you have a bike that holds a line, inspires confidence at speed and encourages smashing into corners and seeing what happens.

Rear End Performance
The Sanction Pro’s suspension feels fairly active and plush giving the rider a feeling of being “in” the bike as opposed to “on” the bike. This can cause rider input to be a bit muted or take a bit more effort when manipulating the bike on trail. However, the upside in the case of the Pro is a large sweet spot and lots of ‘room for error’ when doing stuff your mom would not approve of.

Smaller trail chatter such as mild braking bumps were handled on par when compared to other bikes with similar amounts of travel. That said, I feel I may have left something on the table here. The bike feels so incredibly supple when sitting on it I was often baffled why the bike didn’t eat trail chatter a bit better. Perhaps more a different shock tune could yield the results I’m expecting from the Pro.

The bike stayed very composed during medium and larger sized hits, never leaving me feeling as though the bike was quick to find the bottom of its travel or become otherwise difficult to control. Still, if carrying speed is goal one of this rig, I found myself looking for a bit more compression damping as the suspension utilized a bit more of the travel than I’d like (even at 25% sag). Do not misunderstand me, the suspension was never “wallowy”. For a lighter rider it would perhaps be dead on, I just felt if I could keep the tire on top of the holes as opposed to in them I’d be going faster. To test this, I often I just found myself using the bar mounted compression adjust to find the “middle” position where although harsher, the bike was faster.

Cornering
Despite being long this is one of the best cornering bikes I’ve ever been on. It begs to be smashed into corners and holds a line extremely well when tipped over, tracking where the pilot intends. Its ability to hold speed through the twisties is admirable as it is simply planted. This helps make up for the bike’s lack of get up and go that I sometimes felt on the pedals.

Unlike the GT team athletes, I utilized a 60mm stem on the bike. This is 30mm longer than the 35mm stem the team uses. Why did I do this? Well, the fact is, I am not always riding mega steep gnar. And even when I am, its usually surrounded by more modestly pitched terrain. To add, my number one problem as a rider is properly weighting the front tire through corners, hence I’ve always found a 60mm stem really helps me stay on top of the bike through most of the terrain in North America.

I could see going to a shorter stem and a longer frame if I found myself atop EWS stages every other weekend, but I’m not. And again, my number one problem is staying on top of the bike – and this isn’t exactly short at 48” so I’m guessing I could make the large continue to work for me this side of the Kamikaze downhill.

Overall the bike’s geometry was perhaps my favorite part. Though subjective, the bike fit me really well, had a big sweet spot and had me smashing corners I usually just hold on through.

Braking
The Sanction Pro’s suspension remained neutral under braking. A welcome trait when compared to a number of other high pivot bikes. It isn’t perfect as some stiffening could be felt, but it was on par with the most active linkages I’ve ridden and certainly didn’t penalize late braking into a rough corner or similar.

Jumping
This bike is composed and easy going in the air though it wouldn’t be my first choice as a poppy park bike. It was designed to hold speed and often I found the suspension overly compressing on a landing or lip. Again, this could be due to the lighter-than-I’d-like compression tune, but still, this high pivot bike wasn’t meant to be a dirt jumping tool.

Using the bike to air little features on the trail took a bit more input and manipulation to get the desired reaction out of the bike. Though far from boring it was a bit muted in these situations – which as a racer I’m 100% okay with.

Bad Decision Making
When trying silly stuff, like that gap you aren’t quiet sure you’ll make or that legendary awkward rock double you once heard this guy pulled off, the bike will be there for you in a big way. I certainly started looking for new ways to ride old trail, and more often than not getting away with it. The Sanction Pro really asks to be ridden more like a downhill bike, and this was the most fun part about it. To my point I actually hiked the bike up Glory, a popular backcountry ski run in Jackson, Wyoming and rode to the bottom. Never would have I considered such stupidity on any other trail bike. Just make sure your health insurance is paid in full.

Things That Could Be Improved

Most of the changes I’d suggest for the Sanction Pro would come at the expense of making it a less capable bike in crazier terrain, so take them in that context and decide for yourself how relevant they are to your riding style. However, I’d personally like to see a few things changed.

• The linkage is driven by a combination of bearings and bushings, I’d like to see this 100% bearing driven.
• The shock’s compression tune left me wishing for slightly more support when banging through stupid stuff. Although it may be fine for lighter riders, I’d like to see a slightly more aggressive tune on the larger bikes.
• A touch lower pivot placement may make the bike easier to manipulate without giving up much of its bump eating prowess. Though there is much to be said about a rearward axle path, remember, that axle (wheel) also has to come back to the top of its travel. Hence, when multiple bumps are cycling the suspension, the benefits of a rearward path are nill as the wheel can end up hanging up more. This could be felt in certain situations.
• Slightly more antisquat would help pedaling performance. Again, this will come at the expense of how good the bike is at eating big bumps but a welcome change. Much of the confidence inspiring nature of this bike has to do with the geometry, weight distribution and overall travel. A slightly better pedaling bike would be an improvement not just on the race course but on a “normal” trail ride too, at minimal consequence.
• At 160mm I found the FOX 36 to be a bit less than ideal for the bike’s plush 165mm rear end. A 170 or even 180mm fork would complement this bike even more.
• Add a bottle mount! Some of us hate carrying water on our bodies, especially racers.
• The shock could use some sort of fender to keep mud from spackling it in wet conditions.

Long Term Durability

The Sanction was only tested over a 6-week period but so far the frame has showed no signs of excessive wear nor weakness. The overall frame quality is very good and the Sanction Pro has a very robust feel to it.

Pulling the linkage apart at the end of the test yielded no surprises. Everything seemed to be just as it was when new. Again, the caveat here is that the duration of this test was limited. I'd want to keep an eye on the bushing-driven floating bottom bracket but otherwise the oversized main pivot coupled with a well thought out rear end has me confident this frame would require minimal attention over the long haul. I will be continuing to beat the snot out of the Sanction Pro and will report back if anything out of the ordinary should occur down the trail.

What's The Bottom Line?

Like a Group B Rally Car, the Sanction Pro is an interesting purpose built bike. I applaud GT for building such a specific tool even if it may not be the most marketable bike for a place like North America. Fact of the matter is that a number of enduro races in the US don’t require such a beast, which is perhaps why the company is bringing it into the US as frame only. Still, if you live in a place where you often find yourself pedaling to the top of DH bike worthy trails, see yourself in a place like Whistler on a trail bike, have dreams of competing at the top level of enduro, or simply enjoy pushing the limit in more gnarly terrain on an “ascend-friendly” bike, the Sanction Pro should be near the top of your list. It’s a lightweight downhill bike that can be pedaled uphill.

Update: Long Term Testing Thoughts

About The Reviewer

Jeff Brines didn't go on a real date until he was nearly 20 years old, largely as a result of his borderline unhealthy obsession with bicycles. Although his infatuation with two wheels may have lead to stuttering and sweatiness around the opposite sex, it did provide for an ideal environment to quickly progress through the ranks of both gravity and cross-country racing. These days, Jeff races Enduro at the pro level, rides upward of 150 days a year while logging over 325k of human powered ascending/descending on his bike. Bred as a racer, Jeff is more likely to look for the fastest way through a section as opposed to the most playful. Living in the shadow of the Tetons in Jackson, WY, Jeff works in financial intelligence and spends his winters as head ski gear guru and content manager over at earlyups.com.