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Making sense of the ‘19 GT Sensor 29

43K views 233 replies 39 participants last post by  SergMTB  
#1 ·
The new Sensor has good value, good initial reviews and seems to fit in perfectly next to other exciting new short travel 29ers like the SBG Transition Smuggler. Except for one important geo figure: bb height. Even in the low geo setting the Sensor bb is about 17mm higher than the Smuggler. This might be a welcome change for some with really rocky climbs or tall people who need to run 175mm cranks. It’s also a golden opportunity for those who like to experiment with wheel sizes, specifically mixed wheels sizes: 29 front 27.5 rear. I have played around with the reverse mullet a bit and really really liked it. You get the incredible 29er stability and traction you need through the bars and front end, but the snappy, playful rear 27.5ers are know for.

I started this thread hoping to get some input from knowledgeable ppl on this idea and maybe to inspire some others to try it. Correct me if I’m wrong: the overall wheel diameter difference between 29 and 27.5 is 38mm when running the same tires. If you run a 27.5+ that number goes down a bit. So you’re looking at a 19mm drop in the rear axle height, which will net about 10mm drop in bb height and -1 degree slackening of the hta and sta. The seat can be slid forward to help counteract the slacker sta, making the tt length a bit shorter.

Reverse mullet GT Sensor geo changes:
64.5 hta
75 sta
346 bb height

Sounds like a pretty incredible trail bike to me. I’m in the market for a bike like this and just might pull the trigger when frame sets become available next month.
 
#2 ·
This sounds awesome, I currently have a '16 carbon sensor that i'm wanting to swap frames out of. I'm 6'0 tall running 175mm crankarms and hit everything I pedal over. I have some really awesome gravity based trails(which is the riding I prefer) around here but you have to pedal to the top, and sometimes pretty steep, to get there.

I really love this idea you have. I really would like an AM/enduro type bike because I want a capable descender that I can reasonably pedal to the top of the trail. I think that is what a lot people want, and the 2019 market is reflecting that. Everyone is trying to make the "One bike". Problem with GT though is they're 2-3 years behind the big names, nothing innovative coming out of GT unfortunately, ya know stuff like switchable geo, remote lockouts etc..and the lower price tag for top tier bike reflects that. They probably have ZERO money in R&D because they are now owned by a conglomerate that buys a company for its valuable name and GUTS it for money, they invest minimum dollars to get out every penny they can. That means NO money goes to R&D.

sorry for that lol. None the less, I like new sensor and am interested in a frame set for the right price.
 
#4 ·
The force has a lot more travel and smaller wheels than the sensor. I already have a wreckoning for my big bike. I hear bikes like the sensor or transition smuggler, that is short travel 29er with aggressive modern geo, pedal much better and are more poppy/playful on your average trail when compared to longer travel enduro bikes. This makes them more fun than a big bike on most trails. I also hear they're more fun than normal (shorter wb/reach) bikes in the trail/xc category because they're more stable, easier to ride fast and are more capable in steeper rougher conditions. The last thing I heard was Giant will be releasing a new bike in August that falls into this category. So I'm going to wait to check it out before I decide. But I'm sold on one of these types of bikes for my next one.
 
#7 ·
There is some information on the Trance 29 in the Giant forum, but it's still under embargo, so there isn't anything official I can link you to otherwise:

http://forums.mtbr.com/giant/giant-bikes-2019-rumors-predictions-discussion-1073341-2.html

Just take my word that I got my information from someone who has ridden the bike.

I don't want to sound like "one of those people" but I've never ridden a Specialized bike that I really liked. At this point, unless they happen to be having a demo somewhere I already happen to be, it's not even worth my while to go out of my way to ride one. I do have a friend with a new stumpy who really likes it. But he's more than a little weird. I mean. He's a friend of mine.

I wouldn't look for Giant to suddenly offer a version of a bike with more rear travel than the standard version. Traditionally, they'll do an SX of something with another 10-20mm of fork travel, but that's about it. The best I can offer is this:

The same person who rode the Trance told me if I didn't like that, wait til after Jan 1 2019, that something else was in the pipeline.
 
#9 ·
Definitely doesn't sound like the trance 29 is in the same category as the sensor.
Exactly. Interestingly enough, my wife is on a ...2015? Sensor 27.5. I've long said if they'd made that bike in a 29 I'd have one. Net result, at this point I'm much more interested in the new Sensor than I am the Trance. I have to admit though, I've ridden some terrible Horst link bikes, but I've ridden some great ones too. We'll have to see what category the Sensor falls into.
 
#10 ·
It isn't often you see two different bike models that have exactly the same head tube length, seat tube length and chainstay lengths. The huge difference being fork offsets, travel and shock stroke. I'd venture a guess, without going too deep into it, that the force and sensor are the same front triangle and maybe rear? just the axle to crown and wheel size that are causing that bb height to be high for the 29'er trail category.

55mm stroke shock and some checking, you might have a 150mm 29'er.
 
#11 ·
It isn't often you see two different bike models that have exactly the same head tube length, seat tube length and chainstay lengths. The huge difference being fork offsets, travel and shock stroke. I'd venture a guess, without going too deep into it, that the force and sensor are the same front triangle and maybe rear? just the axle to crown and wheel size that are causing that bb height to be high for the 29'er trail category.

55mm stroke shock and some checking, you might have a 150mm 29'er.
Interesting theory. It might pay to keep an eye on that.
 
#15 · (Edited)
I agree that at least the seat stays are different based on the tire clearance in photos. Ie no way a 29er is fitting in the force rear.

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But I'm still not convinced the front triangles are different. When you look at the geo tables everything matches up with what you would expect by swapping wheel sizes and up forking. I really really like Fanatik and the people working there. But these numbers were pulled off their site and they're obviously wrong: they show the head tube growing or shrinking with the flip chip...

Image


If they are indeed different and someone had both bikes in person they could probably definitively answer. Which looks like won't be possible for another month as Fanatik recently pushed the eta back to 9/15 from 8/15. [emoji20]
 
#20 ·
Will probably be my next bike....the Sensor that is. The Zaskar is great but ready for more travel, front and rear, slacker geo and a bit longer base. Also experimented with 27.5 rear, almost had the room, but the 2.8 NN rubbed and just slowed the bike down. Settled with an Ikon 2.35 and it raised the bike up and added a ton of speed and handling to the bike. Could be different on the new Sensor with boost and all. Be tempted to try out a 29 x 2.6 before going mid sized though....just my .02. :thumbsup:
 

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#22 ·
I'm waiting on a local shop to get one in, but they are currently on BO with no clear date on when one is showing up. The sensor caught my eye as a great budget FS bike that could grow with a rider. Getting the base model and upgrading parts as you outgrow/break them would make getting into the sport a lot easier for most folks.

Also, GT was my first bike. So i have a soft spot for them.
 
#24 ·
LBS has a Sensor Elite in. Had a quick look today.

Looks real good in the flesh. Plenty of room out back around the 2.35 NN tyre. 2.6 clearance I would guess. Semi matte black and the decals are more or less aqua blue. The Groove Tube is neat.

Certainly not a light bike, felt typical trail bike weight, I'd guess around 30lbs for the large just by hefting it.

This is the only one they have and it's for sale not demo or I'd have taken it out briefly, even tho it's too big.

A very neat, no bullshit looking bike.
 
#26 · (Edited)
Yea I got it. Haven't been able to put enough time in to dial the suspension and get a true emic perspective. First off this is a burly trail bike, definitely not a light mellow trail ripper. Holy hell the frame is stiff. Pushing hard with my hands against a carbon wheel I could barely get the seat tube to flex. It's like 5x stiffer than my Wreckoning. The ride is fun and confident. Despite having 5% more sag than recommended in the front and rear it felt firm and rode high. I'll have to ride something chunkier to see if it's harsh, but it felt good on the flow trail behind my house. I felt confident to hit a few good sized doubles on the first ride. I think the handle bar to pedal height aka stack is a bit short. I had a semi odd semi perched feeling when pedaling on the first ride. It comes with 175 mm cranks, which were not as comfortable for me as the 170s I've been running. Even though the seated climbing position felt a bit odd I think the geo is really good for this type of bike. In the low setting with the saddle slammed forward the STA felt just about perfect. The seat tube is superlong, my 32" inseam just barley fits with the 150 lev slammed on the large size.

It was basically fully assembled out of the box, but the lines and cables were not trimmed at all and look laughably long. The derailleur was not adjusted, the clutch seems super weak, oddly the cage bolt was half way out and there's still a lot of play I haven't been able to sort out. There's a rubber protector on the down tube and a few small pieces of clear bra on the seatstays and chainstays. The paint quality is really nice. There's a few disappointing quality control things. The worst is the through hole on the frame for the rear axle is not concentric with the threads on the hanger, so you really have push hard on the axle to thread it all the way from the start. Really feels like cross threading it every time. The ugly is a the paint filed off in the lower shock mounting standoffs, quarter sized. And the annoying is the head tube ornament is off center by a cm. The stem is 40mm on the large, not 60 like the specs say. The rear hub has 18 poe. The wheels with tape but no valves weight 2259g. They're set up with tubes, which are 290g each. Tires are 720g. They're LiteSkin casing which are laughably thin for a burly trail bike. This was a major let down, no way they'd last one ride without tubes and ridiculous pressure. I put my enduro wheelset and xt brakes on before I rode it.
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#31 · (Edited)
So, I haven't done the reveal video yet, but for my part-time YT channel I picked up a large Sensor Sport after selling my Yeti SB5+. I figure it's unlikely I'll spoil the surprise talking about it here, but man I'm excited to show what the bike can do!

I want to put a focus on this as a budget bike because I feel new riders are getting a bad impression that you need to dump no less than $3k to even try and ride out on the trails. Just so not true! Over the next year, I'll be slowly upgrading the bike to help new riders know where to spend their money and how it will help the bike preform better. I know that it's best to just spend a little extra and get the next trim package, but I think a lot of people will want to get the Sport to start and then upgrade after 6mo-1yr. $1,800 + pedals to get out on the trail is hard to beat for a new rider!

My impressions of the Sensor Sport so far:
  • #1 upgrade will be a dropper. Man I miss having one!
  • The stack height is stupid short for such an aggressive trail bike. It doesn't help they only give you 15mm of spacers to play with. The next model needs some stack added to it to help balance the bike a bit better.
  • The shocks are basic, but good enough for some hard trail riding if you pump them up. Plenty for a beginner to learn the basics of suspension tuning and smashing through rough single track.
  • There is some pedal bob when you stand up on the bike, but I think it's more the shock than the linkage. I will be interested to hear from others with higher trim.
  • The brakes are surprisingly good. Not sure how they will hold up long term, but for now they keep me from flying off the trail!
  • The bike tips the scales at 36lbs+... I'm going to be striping down the bike to figure out what parts are adding the most mass so people can figure out what is the best $/lbs upgrade.
  • The stock wheels have a bit of heft for sure. Likely one of the best places to shave weight and make the bike preform better.
  • The WTB Ranger tires are great XC rubber, but does have problems in lose trails here in CO. They don't list the compound used in the tires so I'm going to assume whatever was cheapest.
  • Even with all that heft, the bike climbs like a freaking goat, and loves to carve up the flow. I can't wait to get this bike out on some sump lines and see how it gets on!

As a side note, the GT Sensor has a ton of tire clearance! I put my custom Ibis 938 wheelset in with 29x2.5 Aggressor and have over 8mm of side clearance and 11mm on top. You can also run 27+ on this bike, though I'd flip the chip to high mode just to get some extra BB clearance.

I did slap a 150mm fork on it for the lulz, but would not recommend this. Besides putting a lot of stress on the headtube, it really brings the front up and back, making it a bit of a handful on steep climbs. That said, I think 140mm on this bike would make it an epic bike to carve up the ST!

Here's a photo of it all decked out with 27+ tires and a 150mm fork.
 
#34 ·
I did slap a 150mm fork on it for the lulz, but would not recommend this. Besides putting a lot of stress on the headtube, it really brings the front up and back, making it a bit of a handful on steep climbs. That said, I think 140mm on this bike would make it an epic bike to carve up the ST!

Here's a photo of it all decked out with 27+ tires and a 150mm fork.
View attachment 1219964
You should get an angle set so you can keep the 150 fork without increasing the BB height so much. (though it's odd you called out the low stack height, but then say it was harder to climb with a higher front end?)
 
#33 ·
No doubt it's a heavy bike. The good part is it climbs super well so if anything I only really notice the heft when I lift the bike off the ground. less weight = more better, so I'll be interested to see what's adding all the dang weight!

It's interesting to go on Fanatikbike.com and using their bike builder to see the weight on the carbon frame. A large GT Sensor Carbon frame is 6.51lbs (without shock). For $1,899.00, not that bad when you look at $/lbs. I'm interested to see how much the alloy frame is when I strip it down.