PINKBIKE FIELD TEST
12 Bikes Hucked to Flat in Gratuitous Slow Motion
Literally just what the title says.
Hucks by Adam Price, photography by Trevor LydenMerry Christmas! After a few weeks testing 12 new bikes on some of the world's best trails in Whistler, BC, we brought Adam Price AKA The Privateer up from the office to have a little fun hucking them all to flat. For science.
Well, broscience anyway.
In order of appearance: Santa Cruz Bronson, Yeti SB150, Specialized Stumpjumper 29, Kona Process 153 CR 29, Cannondale Habit, Giant Trance 29, GT Sensor, Yeti SB130, Pivot Firebird 29, Scott Ransom, Devinci Spartan 29.
This was the last Field Test video for the year, and we hope you enjoyed the tests as much as we enjoyed making them. We'll be releasing more video reviews soon, so stay tuned!
Watch all the Field Test videos here.
"For those about to be Hucked, we salute you!"
Scott Ransom actually built to the same standards as the Gambler.. A few people run it with dual crown forks..
And Evil Wreckoning
and YT Capra..
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Being an acual enigneer, The forks are not flexing they are pivoting on the axle.
When the front tire flattens out on some severe flat landings it stops rotating. the bike continues to carry it's momentum forward . this results in the fork pivoting forward on the axle to stay aligned with the forward moving head tube on the frame . Its because the forks are quite stiff and the tire stops that this occurs.
Youll notice you don't see this pivoting when the landing is such that the front tire keeps rotating at reasonable speed. Only when the tire stops due you get this pivot effect you guys are misreading as flex.
Place your finger on 1:38 and click that over and over. you'lll see what I'm talking about.
Having said that, anyone who has ever tested a fork for CSU creaking knows that they flex. 2 seconds with teh google even shows this:
www.youtube.com/watch?v=pRIkdDe6fIM
Also shows how older Chris King headsets used to cut into steerer tubes on long single crown forks due to the headset design and steerer flex. I can't remember ever seeing this issue with a dual crown fork though as the steerer is better supported..
You are speaking utter nonsense there. Surely "as an engineer" you are aware that if these forks didnt flex at all on landing the forces transferred would be enormous. The fork would shatter or rip the head tube off the frame. There HAS to be flex. But as an engineer I'm sure you know that.
Also, "the wheel stops rotating because the tyre has flattened"?!?! What? What engineering qualifications do you actually have? Asking for a friend....
PS I am an electrical engineer so I am infinitely qualified to speak on mechanical engineering problems as long as they are presented to me via the internet.
I realize when any load is applied some flex is present . whether it is significant or visibly detectable is what I'm getting at.
what is predominantly VISIBLE in this video is the pivoting of the fork on the front axle.
worst case of this is 1:38 get a good screen and reclick that section a few times. (you can't do this with a touchscreen phone)
The flex (although present) is BARELY visible.
the pivot Is VERY obvious and I believe most people are not making this distinction.
This pivot occurs because the tire stops rotating on landing it becomes difficult to begin rotating as it's basically a square on the ground just after impact as such the fork pivots on the front wheel axle a bit because this is the path of least resistance to stay aligned with the headtube.
Id like to include photo's in my response to clarify further.
But based on your response attacking my qualification it doesn't appear you would be open to discussion or further thought against your initial assumptions. So likely wont be a fruitful discussion.
If you care to take the time slow it down an notice the line between the shock and the head tube barely wavers from straight on impact the tire stops then the fork pivots forward on the axle to stay in line with the headtube.
To your point the blue yeti I find the flex to be visible on that model. but others the visible effect is dominated by a pivot rather than a flex.
There is some flex notably between the stanchions and lowers but BARELY perceivable. rotation of the fork around the axle is massive but head tube stanchions and lowers stay in close alignment from the unloaded condition as far as the human eye is concerned
I'm open to being wrong cuz i like learning new things and further questioned my initial statement due to the feedback I had from you guys but on further detailed review, I stand by it....majority of what is being seen is not flex.
I still think you are wrong though.
A) There is no way the tyre deformation momentarily stops the wheel. The leverage moments just don't add up. There is a huge amount of inertia driving that wheel forwards, a collapsed tyre with a couple of inches contact patch simply doesn't have the leverage required to stop the wheel.
B) If the fork is rotating around the front axle, without significantly flexing, the back wheel would come off the ground. It doesn't.
I believe what you are seeing is the fork splaying (flexing) forwards on impact, then returning to straight as the load is overcome. The dropouts maybe move a total of 3/4" forward of their normal position, to 1/4" behind, to straight, so the fork does not appear wildly curved at any point, but it is definitely flexing visibly, and the momentary pause in the wheels rotation is an artifact of that, rather than anything caused by the tyre.
A) I don't think it would necessarily be the tyre deformation stopping the wheel. There is a lot of normal force from the ground at that point, so there is also a lot of grip. But it isn't because the wheel would suddenly be "square" which would stop it. Instead because of the head angle, as the fork compresses the wheel also moves rearwards with respect to the front triangle. So as the inertia of the rider is still pointed forwards and down, the inertia of the wheel (and lowers of the fork) is horizontal and at least not so much in the forwards direction. This could cause a CCW moment (from the observer viewpoint). Whether it is flex or pivoting, I've not decided yet. Obviously it is a combination but I've not decided which one is dominant. A way to check this theory would be to do the experiment with a linkage fork like the USE fork or the more recent Weagle fork (forgot the name) which don't move the axle that much rearwards.
B) In a different thread (in the same article) I actually mentioned that the rear suspension seems to stall or the rear wheel even bounces up during the compression phase of the landing. One hypothesis was that it was because the tyre was rebounding whilst the suspension was still compressing. But I can very well imagine the rear end does come up because the bike indeed pivots forwards.
I’d like to see this slow-mo on a bike with a flex-tail / solid chainstays, without a pivot.
me to prove that steel hartails don't do bugger all. its just the material absorbs vibrations and dulls it with shear hefty weight. they are not flexing. then do it we some carbon and ally ones aswell.
I'm actually more curious about what happens with the rear suspension. The all seem to kind off stall at 3/4 of the travel and only then go to full travel. Is this what we call "spiking"? Or did Adam land and absorb the impact and then stomp, which pushed the suspension through its final bit of travel?
May also have something to do with the fact that air springs are f*cking awful. For many reasons. Many many reasons. I'd be interested to see back to back vids, air vs coil.
A) One size fits all, ie they don't have to carry 5 different weight coil springs for every bike they sell. They just sell you a bike and you stick in as much air as required. This saves them lots of money.
B) Air is free. This saves them lots of money.
C) Air is really light. So the total weight of the bike looks better on paper.
D) Air spring volume can be changed, meaning you can build bottom out control into the spring which is cheap and easy, instead of into the damper which is expensive and difficult.
Performance wise though, air loses out to coil every single time.
A) Air changes in temp, changing your spring rate over the course of a ride. A long descent under a heavy rider can turn a bike from a soggy undersprung sofa into a pingy oversprung bastard quite easily.
B) Coil springs are linear meaning your suspension will feel the same no matter where you are in the travel. This is a good thing. If you are concerned about bottom out, set your damping up better.
C) Really rampy air spring setups intended to reduce bottom out, turn your bike into a rock hard undamped pogo stick in deep travel. Your damping settings that you carefully tuned at full extension will be completely overwhelmed once your air spring has gone up from 200psi to well over 1000psi at bottom out. I am irritated daily by the fact that shocks and forks are sold with identical tunes for air and coil springs. The applications are worlds apart.
D) Air springs are sooooooooooooooooooooooo sensitive to maintenance. An air spring that has been ridden hard for a matter of days will perform less well than a freshly serviced one. Coil springs need exactly 0 servicing throught their entire lifespan. Which will likely be longer than that of the bike they are on. Obviously the damper and chassis still need servicing, but so will an air fork/shock.
E) air springs have weird mid stroke issues that are obvious to even the most ham-fisted riders. The more you look into the science of it, the wierder the issues get. The spring rate changes if the piston approaches the rate of pressure wave propagation in the spring are really quite interesting.
Whats the last air spring I rode? Er, I dunno. I work in a high end shop. I ride lots of 2019 bikes regularly. The nicest air spring I ever rode was the one in the Ohlins DH Race fork. It was really really nice. For an air spring.
TL;DR: At the top end of the market (where you probably are) coil springs are probably the better option. Especially with more damping adjustments. But at the more entry level where I probably find myself at, air springs are probably the way to go these days. Simply because cheap air springs are easier to tune than cheap dampers. I'd say there still is a place for an air spring with coil assist in this market. Make it so that for the lowest design weight, the coil would be sufficient and then make the air chamber so small (using oil or whatever it takes) so that it still ramps up near the end. And heavier riders remove oil and add air to make it work for them too.
should have called it the religious link. Read about it and believe blindly.
I'm just as gulable, I still want a sb130.
it does move a microscopic amount yes.
But given this is from full extension to full compression the amount it travels is just ridiculousy tiny. How long are those links compared to how much it actually uses them. So under normal riding conditions with way less travel range being used does it do anything?
maybe it does but this vid doesn't help. I'd need close up vid during normal riding to prove its worth. or back to back testing with one that's had it moving link removed.
kind of for me thinking yeti could have made them single pivots but didn't want to for the snobs.
i still want a sb130 either way.
Will wonderful video! Watching some of those frame flexes help me understand all this chatter about stiffing the frame like trek did.
Thx all and happy Xmas
You can watch the Remedy slow motion here: www.pinkbike.com/news/field-test-trek-remedy-99.html
-makers of flexy bikes
—nobody's butt or wrists
It doesn’t help that on these tests sometimes both wheels hit the geound first and some land back wheel first.
One this is for sure is the stumpy looks bad...
@7:22 then Lars gets way more in the tank for the @7.35 jump
1) Are the front/? brakes being applied? If so, why, is this the only way to "huck to flat"?
2) If brakes are being applied, would a person normally ride like this? and would this be considered a normal huck and be a normal way of measuring flex?
- would all of these top of the line bikes really "huck to flat" with that small of jump/ramp that he showed he was using?
Looks like the brakes were applied to get them to "huck to flat".
This is why that front tire seems to want to spin the other way in some of the vids upon landing.
Cool to watch, but not sure if this is simulating true riding, ??
Maybe PB can shed some details, like is tire/shock/etc pressures are all equal,etc...
11 regular, 1 goofy (SB130) in the thumbnails.
I hope no-one would or wouldn't choose a bike based on this video. I agree with that (extending your point to what I think would be its conclusion).
props to the oldschool handlebar on that mini-huck in the intro.
No - no tokens.
So when you say "no tokens" what you really mean is two tokens?
Who the f put those in there?
merry christmas all.
Knees were feeling ok?
Come on, "tell us how you really feel and remember, this is being recorded for prosperity"
Merry Xmas to 99.8 % of you P.B.ers
youtu.be/0UT2vNQMUy0
However, science had nothing to do with it.
Why was the Marin Alpine Trail not in this test?
Pivot got my attention..
Merry Xmas and a Happy New Year.
Thanks PB for my Christmas present I kind of know it wasn't going to be the HD4
always next year.
f*ck 29ers