The evolution of the Trek's downhill bike continues.
Trek's current Session downhill bike has been in their catalog since 2008, but it has been evolving and changing almost yearly since then. And yes, the Session name was used for Trek's big-travel, single-pivot downhill beast before that, as well as for their freeride bikes, but it's the machine that the Atherton's race aboard that most of us picture in our heads when we hear the Session moniker. And judging by the prototypes that the Athertons were seen riding during Crankworx, including a 29'' wheeled model, it doesn't look like Trek is planning on moving away from the basic design anytime soon.
It does appear as though they're continuing to fine-tune the Session's suspension, however, and quite possibly its geometry.
The shock-less bike pictured to the right is an aluminum prototype, and a closer look reveals that while it still employs Trek's ABP concentric axle pivot layout, it forgoes the Full Floater design that sees the lower shock mount situated on a short extension off the front of the bike's chainstays. This mirrors the 2017 Slash 29er that also nixes the Full Floater setup in order to, according to Trek, create the stiffest frame possible.
The Athertons were likely testing this 27.5'' wheeled prototype back-to-back against the 29'' wheeled downhill bike that was also seen up at Whistler. Now that the Slash is rolling on 29'' wheels, would you be surprised to see the next generation Session go the same route?
m.vitalmtb.com/forums/The-Hub,2/Rachel-Atherton-on-a-Prototype-Trek-Session-at-Whistler,9395&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+VitalMtbSpotlights+
Wait.
It's Frida y= Beer O'clock!
autobus.cyclingnews.com/photos/2007/tech/probikes/sabrina_jonnier_iron_horse07/IMG_0441.jpg
the maiden takes some styling cues from it as well.
There is a big difference in the 29er market.
Which one is wrong? Sorry 9ers aren't for everybody. I'd say if your tall, heavy, or produce lots of power they might work. But I'm none of those so maybe that's why they don't work for me.
www.focus-bikes.com/uploads/tx_dcwnews/BIG_BIRD_FOCUS_Flo_Vogel1.jpg
s3-eu-west-1.amazonaws.com/lot-images.atgmedia.com/SR/34808/2904645/551-201432011335_540x360.jpg
sounds like a proper setup for DH, doesn't even need a chain!!
66.media.tumblr.com/b9b7eda5ce2fa13d445bf1eb47f021c4/tumblr_o9us0uQkRA1utfg94o1_500.jpg
The factors that could cause slower direction changes are BB drop and Trail. The latter can be negated with more fork offset and if the frame has a similar drop to a 650b bike then they'll be little difference there. However, it's pointless having such a high BB as most of the increase in stability is lost.
In summary; an equivalent 650b bike will be just as resistant to turn as a 29" if it has something like a 310mm BB height. Just don't try and pedal it. Here is also the reason why a 29" will always have a stability advantage over 650b. Extra BB drop.
Would do that the 8ft side or the 4ft side?
Plus gyroscopic effect
Part of the touted stability of a 29er is a result of the increased rotational inertial of larger, heavier wheels.
Increased stability does come at a price...more effort to change direction, more effort to bring up to speed. Other design considerations can offset the differences, but not eliminate them.
Smaller wheeled bikes turn faster with less effort and accelerate quicker, but these advantages also come at a price. Smaller wheeled bikes don't carry straight line speed as well, offer less traction, etc...
There are reasons mountain bikes don't come with 20 inch wheels. There are also reasons they don't come with 36 inch wheels.
If you read my previous posts you'll find the answers to your comments.
One is that a spinning gyro in space tends to maintain it's orientation. People with that effect in mind will expect the bike with a larger wheel to maintain its orientation (and trajectory) more easily. And it will be harder to turn if you try to turn the bike by rotating the handlebar and fork around the headtube axis.
The other effect is precession. Compare this with the funny way an angle grinder behaves when you move it around. Or a toll spinning and tilting in circles. If you tilt the handlebar to the left (so push the left grip towards the ground), the front wheel will want to point to the left. And as you tilt the rest of the bike as well, thef whole bike will point in the intended direction but the front wheel will lead as the front end can rotate in the headtube. This way of steering works better the faster you go and the larger the mass moment of inertia of the wheels (proportional to mass and diameter). You'll also use this effect when you want to twist of orient your bike when in the air. I don't know if anyone ever dared to try but it really won't work when you lock your wheels in the air so that they don't spin.
In fact, this precession tends to push a bike back upright if you apply the technique of turning the handlebar around the headtube axis. This is clearly not what you want and will indeed give you the feeling that the bike doesn't want to turn at higher speeds.
So whether it is quicker to steer a small/light wheeled bike or a big/heavy wheeled bike depends on your technique and speed. And yes, the small increase in size does matter as mathematically the diameter goes to a higher power in the equation so that adds up quickly.
Does this mean that I think bigger wheels are better for going around corners? No, I'm not that fashionable. I run heavy 26" wheels, tubes and tyres. They're well over modern 29er weight (probably) but at the same speed, a 26" wheel has to spin faster. So I'm getting this effect on the cheap .
I owned a 29er for aboot 9months an went back to 26 because the 9er didn't handle as well through tight fast single track, trails with lots of fast direction changes. I didn't feel any extra grip, at at all
There was better roll over speed an my average speed on a 20-30 mile ride was about 1-2mph faster
But, the bigger wheels where just to much hard work an no FUN. faster on fire roads but, that's boring as f*ck.
Having way more FUN back on 26 with fat (but, not plus size) tyres
So yeah f*ck your science, I'm ripping trails not building rocket ships
I'm also bemused as to why you'd think it's easier to flip the ply length ways rather than width??????
A big ultra fit athlete like Gee may be able to tolerate the extra work and ride faster in most terrain on a heavy 29in DH bike. But, for smaller riders the drawbacks associated with extra rotational inertia become more significant.
I don't know where downhill is headed, but for Enduro racing, I would expect 27.5 in wheels will still be the choice for many medium to small riders, especially on tight, twisty tracks.
Also, keep in mind that there is more to gyroscopic precession than just inertia. The angular velocity of the wheel matters as well and for the bikes traveling at the same speed, the angular velocity of the big wheeled bike's wheels are smaller.
(sarcasm btw )
That's it. I'm out.......
So either rear suspension has gotten that much better to eliminate this mid travel "issue" oooor the actual gain from full floater was very minimal to start with and more just marketing....
www.bikerumor.com/2011/02/23/spy-shots-trek-29er-downhill-mountain-bike-prototype
And Intense messed around with the 2951 before making a 650b 951:
www.vitalmtb.com/photos/features/Intense-2951-29er-DH-Bike,950/2951-next-to-a-951-29er-vs-26er,2940/sspomer,2
29" wheels for Gee to boost his competitiveness and
20" wheels for Rachel to get her some challenges in the world cup.
Round wheels for the win.
Of course if they build a bike that dominates the competition, then they'd actually gain customers from it so...
Gwin seems to win on any bike he's offered.
I hope they do this - if 29ers are so fast it will be interesting to see how much faster Rachel is and whether Gee makes the podium again.
My bets on not much change in the status quo even if they do...
If dropping the "full floater" in their suspension design was all in the name of frame stiffness for the new Slash 29er and now these DH prototypes, why didn't Trek do the same with the new remedy and fuel ex bikes?? They went through the trouble of creating the knock-block keyed headset to key the fork from hitting the new straight down tube in the name of stiffness. So, why not drop the full floater on the Remedy and Fuel Ex? Is it that only the most elite riders will notice the difference in stiffness when it comes to a Trek with full floater vs a non- full floater Trek (all other things being equal)? Is it that modern suspension and damper designs just don't need the claimed benefit of the full floater anymore?
Trek has been using "metric" shocks for years now (try converting their funky inch measurements into milimeters. It seems like a sound theory to me and lines up close with current metric spacing options) and because of this, the engineers can revise linkages and use a shock specific to their new and improved design (the whole point of metric shocks). Now that they have a better linkage, they have made the full floater irrelevant and inferior to the new design therefore antiquating it.
I think the use of a smaller shock on the remedy and fuel ex is why trek is still using a full floater on those bikes; they can still fit the same shock and a full floater on a small frame.
Just the perfect bikepark machine.
when this happens I want to see what they gonna say..
www.pinkbike.com/news/trek-tour-29er-proto-2011.html
I really want to see a ground-up redesign for the session to be honest, Horst-link designs with 2-pivot chain stays are boring.