I'm not sure Josh needs an introduction but it's fair to say he has been on one hell of a journey over his riding career. These days Josh can mostly be found just having fun on bikes and that is where this bike comes from. It's the first time Josh has raced it and it's not built to be an out-and-out race bike. It's a bike to escape on and have some fun. That's not to say it can't be a race bike as well. Josh raced it at the Ard Rock enduro, which is one of the toughest enduro races in the UK and he placed in the top 10.
 | It's the first time I've raced this bike and I really enjoyed it. Dropped the chain on stage one which was weird as it's never happened to me in 2 years—Josh Bryceland |
Josh rides a medium Cannondale Jekyll frame which, considering Josh is 6'2", is an interesting choice. This is the frame-only option of the Jekyll which gets a different graphics kit than the standard Jekyll with the pineapple headtube badge. The new Jekyll from Cannondale is a 4-bar design combined with a high pivot idler set up more common with a downhill bike than your run-of-the-mill trail bike.
Under the removable down tube protector you will find a Rockshox Super Deluxe shock providing 165mm of rear travel. Josh runs 180psi in his Super deluxe paired with a set of 170mm RockShox Lyrik Ultimate forks running 85psi air with 3 tokens installed, along with 10 clicks of HSC and LSC. Josh likes his bike to feel balanced in its suspension set up with a slightly slower rebound than you might expect. Like most riders Josh wants his bike to be as predictable as possible. He did have a set of 180mm Rockshox Zebs fitted however this made the bike feel a bit too stiff and unsettled for Josh's liking so he ended up with the 170mm Lyrik you see fitted here.
When it comes to drivetrain it's a full set of SRAM's X01 components for Josh, with the Eagle 12-speed rear cassette combined with a Burgtec 32t silver chain ring.
Interestingly there is a short set of cranks fitted to Josh's bike. These are 165mm long and have a set of the very popular Burgtec penthouse flat pedals again in silver.
Brake-wise it's more SRAM parts for Josh as he uses SRAM's Code R brakes with some SRAM metallic pads fitted. For rotors there are a pair of 200mm SRAM rotors fitted front and rear.
For handlebars it's Josh's signature Ride High aluminium handlebars from Burgtec cut to 780mm. These bars have 50mm of rise and are not your normal kind of bar you find on an enduro bike but Josh isn't any normal rider.
There are more Burgtec parts fitted for the stem with a 42mm Burgtec Enduro MK3 Stem installed with a 10mm spacer under it. Again all the hardware is from Burgtec.
For wheels Josh has a set of Santa Cruz Reserve carbon 29" rims laced to a set of industry 9 hubs. Wrapped around these are a set of Maxxis tyres with an Assegai Exo fitted to the front running tubeless and at 30psi. Out back there is a Double Down Aggressor with 40psi of air in it and a Fck Flats insert fitted.
It's more AXS parts when it comes to dropper with a RockShox Reverb AXS fitted on top of which there is a Fabric saddle fitted.
A massive thanks to Josh for doing this bike check when he was already a bit behind on his day at Ard Rock.
Insert doesn't diminish the area of the tire+rim "round" cross section, so there is still as much square inches where as much lbs are applied, as without and insert.
Also, one of the main points of the relatively heavy foam is so that you can run a lower pressure without fear of losing the bead or destroying rim.
Two separate things going on here. The tire not only supports the rim, but also acts like a spring between the ground and the rim (think feel).
The support part is defined by Boyle's Law PV=k (a constant)
P/V (without insert) = P/V (with insert)
so if the insert reduces the volume the pressure would need to be reduced to get the same physical pressure system.
The "feel" part is governed by spring constant or Hooke's Law F= -kx
In this case, k represents the characteristic of the spring or tire "feel" in this case.
x is the available travel distance between the tire and rim
The force (F) = PA (pressure x area) The area is the rim surface, which is constant.
So the feel (k) = P/x (assuming A is constant)
This means you would have to increase the pressure to get the same feel with the insert, which is reducing the x.
So depending on all the actual parameters, the pressure with the insert could be higher than the original pressure. if you are trying to match feel.
Guessing that Josh was smashing trails and winning world cups rather than studying physics, he put inserts in to keep from getting flats and kept raising his tire pressure until it "felt" like his setup without inserts.
Cheers!
The equations aren't wrong, but the model does not represent the physical situation. The model presented above assumes a tire and insert system allows the tire to compress only to the insert, not the rim. The actual situation is that the tire still compresses to the rim (or a millimeter or two short of the rim, though often fully to the rim, as many inserts split during a maximum compression event). The best model is probably that either situation - insert or none - produces a deflection that stops several millimeters short of the rim. You don't want to be bouncing off your rim or testing the yield strength of the insert on the set of typical impacts that comprise what we're describing as the "feel".
Thus, x (distance) is not reduced and the insert adds a secondary spring.
If the tire without insert is:
F = k(tire₁)x(tire)
The tire with insert would be:
F = k(tire₂)x(tire) + k(insert)x(insert)
Since F is approximately constant (assuming the limiting factor for pressure is preventing rim strikes):
k(tire₁)x(tire) = k(tire₂)x(tire) + k(insert)x(insert)
k(tire₂) = k(tire₁) - ( k(insert) × (x(insert) ÷ x(tire)))
Therefore, k(tire₂) is lower to produce the same rim strike force and will feel softer at all points in the travel.
We could equate the total energy, rather than maximum force, and get a different equation, but the conclusion is similar.
@R-M-R pointed out one of them, with "x" not being reduced by the insert.
My main gripe about the physics that are mentioned, is F=-kx : which only applies to a mono-directional spring like a tube in a tube cf shock/fork.
A tire is not rigid like fork lowers, air pressure pushes in all directions including sides. I don't know how that tension is called, but imagine the tire's contact patch as a trampoline, hard to deform because stretched in all directions in a 2D plane.
This is why a 23c road tire at 30psi doesn't feel like a 2.5" mtb tire, even in the first 1cm of deformation, cf aforementioned "X".
This is also why rims have pressures limits linked to tire size (big tire, no 50psi allowed).
I guess they aren’t active enough
Starting with Boyle's Law, PV = k, k is a constant, but not the same constant. When you bring in the more robust Ideal gas Law, PV = nRT, you will notice that n, the number of the moles of air in this case, would be different for a insert tire and one without because there is less volume. Boyle's law is used to calculate and estimated pressure for a change in volume- assuming isothermic, ideal gas conditions (probably close enough in this case). If you picture the volume of an entire bike tire- and how much it changes when you compress it to a rim, its not a large change in volume at all, so the change is pressure is similarly small (going to conveniently ignore the tire's volume expanding with pressure here). With an insert, it is a larger proportional volume change, so the pressure change will be higher (more progressive), although again it probably isn't that different.
Hooke's law is simply an empirical law for linear springs, I'm not sure it's applicable here. The force a tire exerts on the ground (spring force, I suppose) is a function of the pressure (assumed to be calculated by Boyle's law above as the volume reduces) times the contact area of the tire touching the ground, which will be some non-linear function of tire width, tire diameter, and how deformed it is (on its way to hitting the rim). Plus you must add in casing stiffness. We could maybe try to linearize this and apply Hooke's law here, but then you feel the spring constant, "k", not the "x". "x" is the independent variable. So "k" is dependent on pressure and contact area. With or without an insert- the contact area for a given deformation is nearly identical and the pressure is probably quite close too- so *key point* until you deform the tire enough to hit the insert- the feel should be very similar for the same pressure with or without an insert.
So to explain the difference in feel- until you hit the insert, it should feel similar, with the exception of tire roll, which is its own topic altogether. Once you hit the insert, the spring force is more governed by the insert's behavior under compression. Since this will be completely different than the air-only tire, both in force and also damping, comparing the two in the second half of tire compression is harder. The reason people run lower pressures with inserts is, in my opinion, more because they can get away with it without destroying rims than matching feel.
TL;DR Engineering argument, I don't think the justifications of some people's arguments here hold water. Feel at the same pressure is roughly the same until you hit the insert, then feel changes dramatically.
I recall a few years ago people were complaining about how bikes would only grow slightly per model year instead of companies just jumping straight to the "correct" geometry. I think they have arrived now. There is good bike geometry for nearly everyone now.
Slack seat tube angle compensates for a shorter reach.
And ultimately just preference. I own a ~1200mm bike with a ~450mm reach as well as a ~1280mm bike with a ~500mm reach. Neither is "wrong." I very clearly feel more comfortable in very fast or very steep stuff on the longer bike, but I love the shorter bike too. They excel in different situations but even a 50mm delta in reach (people seem to agonize over 10-20mm) isn't going to make a bike unrideable or anything near it. Just different.
Obviously some people will object but IMO i find the shorter ones, in the 475 range to be in the range of "more fun" i can move my weight where ever i want, where as when i rode bikes like the commencal meta It took alot more effort to force it to do what i wanted as there less leverage in your weight movements.
I've been lucky enough to own alot of bikes (usally through buying frame sets) so i've been able to ride them in the same locations.
For a large, Ive found 475-480 work the best for me everywhere from my local pedal ups to the bike park - i ride my bike for fun and have no interest in going warp speed in a wide open area(i just dont find that fun)
Most of those bikes like the altitude and Sentinel can handle a 240 dropper which is a huge plus.
Surely this merits a refund amirite?
Hopefully supply chains will sort themselves out soon and we can buy DD and DH casings again...
I see gold on bikes and think of rappers' grillz.
Would read the sh*t out of an article analysing this question - which CS length is the one the frame designer compromises least with, or at least the tradeoffs made in the design and the corresponding ride feel, balance etc!
Bike design has converged in many ways, with geometry and kinematics starting to cluster around some popular values in the middle of the bell curve (there are, of course, still some wonderful and some abysmal outliers). Bikes may have different suspension designs - SS (short & short links, such as dw, Maestro, etc.) vs. LS (long & short, such as Horst) - yet may feel nearly identical due to nearly identical kinematics and shock tunes.
Sizing, however, throws all this out the window. The difference in kinematics between sizes for a given model is often greater than the difference in kinematics between models. Bike X and Bike Y in the same size are likely to feel more similar than Bike X size Small vs. Bike X size Large - not to mention the problems of using the same shock tune for riders who are putting dramatically different amounts of force into the chassis.
We all know the geometry of a bike has to change to suit different rider dimensions, but other parameters aren't as visually obvious. Kinematics, shock tune, frame stiffness, etc. also need to change to suit the rider.
First thing I thought too, no way he's racing...or riding at all with Code R's.
Tell that to our bungling president who’s been quadruple vaxxed and still got it. Bryceland is exactly the demographic that has zero to worry about. Let the dude live his life.
Fair enough.
Though I'd still say spreading willful ignorance like saying Bungling Biden got the shots purely to prevent it, rather lessen his chance of dying, therefore the shots are ineffective so why bother is absolutely still harmful and should be responded to, politely or not.
to quote directly from the CDC
"we wanted to interfere less in day to day life..." #wewerewrong @loam33 gets it...EMPIRICAL DATA vs Anecdotal....this is such a freaking impossible concept for libs to grasp.
Statistics are such a bear for the main stream media fed. Learn to think for yourself.
@adamszymkowicz yeah... guess what sometimes critical thinkers vote independent. shut it fool,
Yes, actually. The same empirical data shows the earlier variants had much higher mortality rates than the variants that are prevalent today. The initial global response being heavy handed or not may be up for debate, but is definitely overkill for the current situation.
Can we get back to discussing the bikes now please?
However...the virus also worked it's way through all those with co-morbidities and the herd immunity (that so many called for...) is now there.
the Chief of staff at our big regional hospital said in a recent interview..."The # of fatalities we had was going to happen, whether in 3 months or 2 years...those with co-morbidities were going to bear the brunt of it"
which is why it's dumb to ding Bryceland for not wanting to get the jab...he's the least likely demographic to suffer from covid.
That’s pretty annoying
A picture isn’t always worth 1000 words.
Get it together!