Tech From The Andorra DH World Cup 2018

Jul 11, 2018
by Ross Bell  
The dormant bike of Aaron Gwin who has flown back home to recover from his thumb injury.
The dormant bike of Aaron Gwin, who has flown back home to recover from his thumb injury.


After a frantic race and an equally frantic pack down in Val di Sole, the World Cup circus has rolled into the town of Vallnord, nestled away in the deep valleys of the Andorran mountains. Being a back to back round means teams and their mechanics have their work cut out, getting pits setup and prepping bikes for the onslaught of Vallnord's steep track. We've been out for a lap of the pits to see what's being bolted onto the bikes this weekend:


A standard flat out Wednesday for the FOX boys.
Vallnord Pit Walk
A standard flat out Wednesday for the Fox boys.

Brake bleed going down on Kye A Hern s Canyon Sender.
Brake bleed going down on Kye A'Hern's Canyon Sender.

Brendan Fairclough s BOS shock gets a little TLC.
Brendan Fairclough's BOS shock gets a little TLC.

Yet another bike with an idler system. SCOTT s prototype is the latest to join the club.
Yet another bike with an idler system. Scott's prototype is the latest to join the club...
Vallnord Pit Walk
...Cobbed up with washers for spacing and a bolt screwed into the swingarm pivot.

Loic Bruni s Specialized Demo.
Loic Bruni's Specialized Demo.

Rebuilds aplenty in the Propain pits.
Rebuilds aplenty in the Propain pits.

The Norco Factory Racing riders have two linkages at their disposal a harder and softer tune.
Vallnord Pit Walk
The Norco Factory Racing riders have two linkages at their disposal, a harder and softer tune.

We spotted some prototype Kenda tires in the Polygon UR pits.
We spotted some prototype Kenda tires in the Polygon UR pits.

A well spaced mud spike that looks set for it s debut this weekend.
A well-spaced mud spike that looks set for its debut this weekend.

AB Devinci s Wilson equipped with an Extreme Racing Shock coil.
Vallnord Pit Walk
AB Devinci Wilsons equipped with an Extreme Racing Coil Shock.

Steep tracks such as this weekend in La Massana often see riders raising their bar height.
Steep tracks, such as this weekend in La Massana, often see riders raising their bar height.

Chunky brake mounts on the Commencal 100 team bikes.
Chunky brake mounts on the Commencal 100 team bikes - 230mm rotors?.

Bruce Klein is back racing and on an air shock...
Bruce Klein is back racing and on an air shock...
... whilst team mate Thomas Estaque is on a coil.
... while teammate Thomas Estaque is on a coil.

Fresh frames and colourways for Cube s Matt Walker and Max Hartenstern.
Vallnord Pit Walk
Fresh frames and colorways for Cube's Matt Walker and Max Hartenstern.


Danny Hart s Saracen Myst got it s first taste of World Cup podium last weekend.
Danny Hart's Saracen Myst got it's first taste of World Cup podium last weekend.

Marcelo Gutierrez s DVO equipped Giant Glory.
Marcelo Gutierrez's DVO equipped Giant Glory.

Vallnord Pit Walk
Vallnord Pit Walk

A fresh Maxxis Assegai for Emilie Siegenthaler.
A fresh Maxxis Assegai for Emilie Siegenthaler.

The Pivot boys are wanting in on the data acquisition games and have perhaps the most sophisticated system we have seen to date... Engineered by none other than Eddie Masters himself. More details coming soon.
The Pivot boys are wanting in on the data acquisition games and have perhaps the most sophisticated system we have seen to date... Engineered by none other than Eddie Masters himself. More details coming soon.

Pivot are going to need a bigger rack soon with each rider having upwards of 3 bikes each.
Vallnord Pit Walk
Pivot are going to need a bigger rack soon, with each rider having upwards of three bikes each.


Evan Warner gets to work on one of many Boxxer services today.
Evan Warner gets to work on one of many Boxxer services today.

Cecile Ravanel is back racing downhill this weekend and looks to be on 29 wheels.
Cecile Ravanel is back racing downhill this weekend and looks to be on 29" wheels.

Mick Hannah is running Trickstuff s new Maxima brakes which have a claimed 25 more power than the already super powerful Direttissima.
Vallnord Pit Walk
Mick Hannah is running Trickstuff's new Maxima brakes which have a claimed 25% more power than the already super powerful Direttissima.

Gold World Champ bling on Miranda Miller s demo.
Gold World Champ bling on Miranda Miller's demo.

Clear grip tape on Recce Wilson s shifter.
Reece Wilson uses Rev Grips suspension grips and puts clear grip tape on his shifter.

Noel Niederberger s NS Fuzz 29er.
Noel Niederberger's NS Fuzz 29er.

The stunning UNNO team bikes.
The stunning UNNO Evers setting pretty.

Taylor Vernon has gone for an Ohlins coil for practice tomorrow...
Taylor Vernon has gone for an Ohlins coil shock for practice tomorrow...
... whilst team mate Greg Williamson has gone for a FOX air shock.
... while teammate Greg Williamson has gone for a Fox air shock.


Jack Moir is back in the game.
Jack Moir is back in the game.

The Intense boys are all relatively similar weights but run different springs because of differing riding styles more than anything. Dean Lucas is on a 500lbs whilst Charlie Harrison and Jack Moir both run 550lbs.
The Intense boys are all relatively similar weights but run different springs because of differing riding styles. Dean Lucas is on a 500lb, while Charlie Harrison and Jack Moir both run 550lb springs.

A rack of GT Force and Sensors.
Vallnord Pit Walk
A rack of GT Forces and Sensors.

Linkage detail on the Santa Cruz V10.
Linkage detail on the Santa Cruz V10.

Devinci have run out of riders with all three laid up injured luckily Keegan Wright from their EWS squad has decided to race these back to back rounds.
Devinci have run out of riders, with all three laid up injured. Luckily, EWS racer Keegan Wright has decided to race these back to back DH rounds.

Laurie Greenland has opted for DT Swiss EX471 rims over the EX511 that he has run in the past and team mate Mike Jones is continuing to run. His mechanic says the offer a little more compliance on the steeper and more technical tracks.
Vallnord Pit Walk
Laurie Greenland has opted for DT Swiss' EX471 rims over the EX511s that he has run in the past (and teammate Mike Jones, on the right, is continuing to run). His mechanic says the EX471s offer a little more compliance on the steeper and more technical tracks.



87 Comments

  • + 209
 “Hmmm I’m racing a full EWS Season, but my team need me. Better get the big bike out...”

Keegan Wright you’re an animal mate, mad props
  • + 105
 It was the Wright thing to do, for sure.
  • + 27
 At Val di Sole he competed in the 4X Worlds and skipped the DH WC qualification. At crankworx he took part of pumptrack, speed and style, DH... That dude just loves biking Big Grin
  • + 43
 I live 5 minutes away from Vallnord, and was walking around the pits today as well.

It feels like walking into a candy store, but you can't eat anything - torture and frustration.

However, those bikes look damn good.

If I had to pick one for myself, it would be a 29" Santa Cruz.
The new frame looks sick and I love the color. It's a pretty and subtile grey.
  • + 11
 The pictures are so vivid I could imagine i was there. Like candystore technicolor
  • + 5
 You are a lucky human.......looks like a kick a$$ place to me
  • + 39
 SO MANY THINGS I NEED!! NOT WANT NEED!!!! .............ok fine its want.........
  • + 30
 You need them to get rid of the want feeling.
  • + 28
 That gambler idler is prime candidate for GMBN's "hack or bodge"...
  • - 1
 I think that's where they got the idea, or perhaps the do you need a chain video
  • + 2
 I had a Ghost DH 9000 with the idler a while back and everyone laughed at it because, admittedly, it was a bit ugly; but it worked. Guess I should have kept it as it's now cool again. . .

Oh, wait, it was 26", so un-ridable! I forgot! Smile
  • + 21
 What's up with the crazy caliper spacers? I realize its a huge rotor, but it seems like there could be a better design to mount your brake onto your bike . . . .
  • + 12
 Agree, looks weird. Anyway, BRUCE is back & same with JACK! Send it boys!
  • + 2
 @mtbmaniatv: all that force going through three chainring bolts looks a little bit dubious to me. I hope it holds up!
  • + 1
 Can't be too bad - Pierron's set up for Val Di Sol was similar p.vitalmtb.com/photos/users/2/photos/123115/s1600_VDS18_AN3X1944.jpg?1530994429
  • + 2
 @ButtersNZ: Everything is on the vibration damping stickers !
  • + 19
 yeahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
  • + 8
 YYYYEEEEEHHHHH!
  • + 3
 Yeoooww?
  • + 11
 How high do brake adapters have to get before flex starts being an issue I wonder.
  • + 4
 Since the torque it takes to lockup a wheel/tire is independent of the rotor diameter, the deflection of the adapter won't change a whole lot regardless of how far out it moves the caliper.

If the rotor was infinitely large, the forces at the caliper would be 0 and there would be no deflection. Same reason why you can grab the wheel by hand while it's spinning no problem, but good luck trying to grab the rotor.
  • + 1
 @SoDiezl350: that is true, but there must be a greater force going through those three tiny little bolts holding the dropout on to the frame, no?
Are they up to task do you reckon?
  • + 9
 @jaame: On that particular commencal, the frame and caliper adapter mate in such a way that the braking forces (when moving forward) are transferred through the caliper, into the adapter, and subsequently into the frame boss. The bolts are there only to hold the adapter up against the frame.

On a more conventional frame, the bolts securing the adapter are loaded in shear when the braking forces are transferred from the caliper to the adapter. This shear force is however equal to the force the rotor exerts onto the caliper. Since the force to lockup the rear wheel goes down as the caliper moves further away from the center (due to more leverage), the shear force on the bolts decreases as well.

It's important to note that in almost all competitive vehicles equipped with disc brakes, the size of the brakes is not determined by strength/power considerations, but rather by thermal properties. Racing brake pads like to operate over a fairly narrow temperature range, while the brake fluid will boil above a certain temperature. The most common cause of overheated brake pads/boiled fluid is the brake rotor being too small to effectively dissipate all the thermal energy it's absorbing. You generally want the smallest rotor that won't overheat your pads/fluid.
  • + 14
 @SoDiezl350: Sorry to be the engineer in the room, but that's not really correct. The reason I say this is that deflection is not linearly proportional to the length of the deflecting member. Using the example of a simple cantilever, if the length is doubled but all other parameters remain the same then the deflection will increase by eight times. The force required to produce a given torque changes linearly with distance. So even if the force is halved by doubling the mounting length, the deflection will still increase by four times.

To further complicate things, just because less force could be used to slow the wheel at the same rate doesn't mean it will be. The brake caliper is still capable of applying the same clamping force regardless of the mounting position. So even though the rider could achieve the same angular deceleration as with a smaller mount by pulling the brake more gently, they probably won't because that would defeat the purpose of increasing the mount size in the first place.
  • + 6
 Another apologetic engineer here. Your understanding of the forces in the brake/axle mount are also a bit skewed. Because torque is a free vector (meaning it doesn't matter where you apply the torque, it's always a twisting motion) the brake mount will want to twist out of the frame in a clock-wise direction. The bolts are loaded in shear when the brake is applied.

The torque applied by the brake is (as you point out) limited by the traction of the tire/dirt so assuming sufficient power of the brakes you're right about thermal concerns being paramount. Larger rotors also mean that it takes less lever force to reach the torque limit of the brake (aka, locking up the rear wheel) and since that lever is powered by the rider larger rotors on steep tracks can result in an improved rider experience.
  • + 44
 I like turtles
  • + 2
 might as well get some rim brakes : )
  • + 1
 When they snap.
  • + 2
 @waat: You win - Best comment ever :-)
  • + 1
 Interesting explanations. Thanks for those.
  • + 2
 @Dhminipinner: The max force doesn't change much, the limiting factor is that the wheel will lock and stop rotating at the same braking force no matter what size rotor is used. A bigger rotor will make it easier to reach that point quicker so you can go from no braking force to max force quicker, therefore brake a little bit later, so go faster, and the cooling benefits.
  • + 1
 @Dhminipinner:

I'm sorry, but I'm going to have to respectfully disagree with some of your assumptions. You are correct that deflection is non linear and increases to the power of 3 with respect to length, however this only applies for a cantilevered beam. Pretty much every frame is designed to minimize the level of cantilevering of the brake mount, which is true of this Commencal as well. The tangential force at the caliper acts to compress that mount a lot more than it tries to bend it. For a beam in compression, the linearity of Hooke's law still applies.

As for the effort required at the lever, all of my statements are based on the peak load that occurs when the tire is at the threshold of locking up. At the lockup point, the force at the lever and subsequently the caliper pistons will be lower for the larger rotor.
  • + 1
 @SoDiezl350:

I totally agree that you wouldn't actually analyze this system as a simple cantilever. But looking at the geometry and the direction of the applied load, I think it would be foolish to study the system without the inclusion of bending. To me it looks to be the dominant effect, however this is based on my intuition only.
  • + 1
 Woah man, people pulled their slide rulers out of their pocket protectors! Big Grin Thanks!
  • + 11
 my favorite card game is UNNO.
  • + 4
 A Gambler doesn't play UNNO.
  • + 2
 @AlexS1: Stop with the punnos... Wink
  • + 8
 I'm so far away from being a 'Specialized Guy' that you can't see me..... but damn, Loic Bruni's Specialized is awesome!
  • + 5
 Did the track walk today. Some corners on the bottom half have been cut to make them straight. Steep as f* and greasy too with rain expected every night for the next 4 days. Gonna be a belter of a race where big balls will prevail!
  • + 8
 What, no Rotor 1x7 hydro drivetrain? Too soon?
  • + 5
 What does compliance mean regarding rims and steep terrain?

"EX471s offer a little more compliance on the steeper and more technical tracks"
  • + 10
 I’m guessing flex over the janky stuff so as not to yank the bars, bike and rider around so hard.
  • + 9
 Stiffer wheel is better/more supportive for pumping on the more high speed bike-parkish tracks maybe? More compliant wheels grip better on softer surfaces where there is less grip to begin with?
  • + 3
 Vertical compliance in a wheel is great for keeping both your hands and spokes loose over rough terrain.
  • + 1
 I'm assuming this means they yield/dent a little more readily without allowing the tire to burp. Anyone else have input? @zuestman ?
  • + 2
 @sngltrkmnd: well alum will actually be better on the hands. this track will be brutal on hands so something with a little flex can be a lot easier on the hands. Also, while everyone think stiffer the better, a wheel that can "conform" (flex) a little bit under load holds traction much better. Obviously too flexy is crap, but some give will keep the tire gripping the dirt. More likely what they are talking about.

But, as you said, a little dent here and there can actually help save a run instead of cracking/breaking.
  • + 6
 That Trickstuff Brake is what i want for christmas
  • + 1
 You're not the only one. This is a piece of art. Smile
  • + 4
 From what I hear that is about how long it takes them to deliver. So order today ;-)
  • + 5
 Bring back the ball burnished aluminum GT frames...please oh please Smile me buy !
  • + 3
 Zaskar rts lts mmmm..... ballsssss
  • + 3
 Damn *clear* grip-tape on the shifter paddle is one of the most factory things I've ever seen. God forbid you can't see that sweet sweet XO logo... Razz
  • + 1
 I'm by no means an engineer, but holy hell, if you're going to run a brake rotor that big, at some point don't you get a manufacturer to make you a bigger caliper/piston(s)? Is it just about heat and not stopping power so they want a huge rotor but the standard caliper is fine?
  • + 1
 Seems like there's an increasing number of riders racing with complete bike in this race. Compared to last race where most riders only raced with a frame, or most with only rear wheel.
  • + 0
 This speech is my recital, I think it's very vital To rock a rhyme that's right on time It's Tricky tricky, here we go It's tricky to rock a rhyme, to rock a rhyme that's right on time It's tricky, it's tricky, tricky
  • + 2
 With the back to back photos of Intense and Unno you can feel the lineage between these two frames
  • + 1
 César Rojo is behind both bikes engineering, after all.
  • + 2
 Gutierrez bike is the best:

"Esto és un negocio loco"

"This is crazy stuff"

(not the most accurate translation)
  • + 1
 close enough , more like "this is a crazy job" as far as its sentiment .
  • + 1
 good enough amigo
  • + 14
 What am I looking for?
What am I doing here?
The one above accompanies me.
What if this were the last time?
Chicken or pig?
Does each step take me where I want to go?
Am I present? Am I feeling it?
Where do I come from?
Where am I going?
Simplicity and humility.
Capacity to adapt.
This is a crazy job.
White wolf or black wolf?
Am I ready to pay the price?
Passion, magic, love and winning.
You must believe!
Optimism. Enjoy.
You can.
  • + 4
 @acali: Thanks for translating. Pretty inspiring stuff from Marcello. Poster worthy!
  • + 1
 Aren't the 471 rims tube only or do dh guys all ride tubes. Excuse my ignorance. I have never ridden a big bike.
  • + 7
 no such thing as tube only. Gorilla tape, motherfucker.
  • + 2
 data acquisition on a MAC, good boy.
  • + 1
 Can anyone answer why Devinci is running there alloy Wilsons and not there carbon versions? Thanks for the great write up!
  • + 1
 I happened to be reading a couple of reviews on the weekend, and a couple of them said the alloy bike feels better. Or maybe they are protos
  • + 2
 They're running the 29 prototypes aren't they?
  • + 1
 @YouHadMeAtDrugs: yes
  • + 2
 Was that an aluminum Pivot Phoenix in the mix?
  • + 2
 Aren’t the 29 Phoenix Alu??
  • + 1
 Yes and Yes.
  • + 1
 @PAmtbiker: Do you know anything more about it? will they be selling them?
  • + 1
 @iluvchocmilk: Not yet. Pretty sure they're protos, thus 29er, and carbon.
  • + 1
 the Pivot team has the best data acquisition team!
  • + 1
 alloy probly feels... " more compliant"
  • + 1
 the saracen of danny hart looks fast...
  • + 1
 Awesome pictures and writeup. Well I can't read so awesome pictures
  • + 1
 Agreed. The pictures look so good. Great job Ross Bell.
  • + 1
 OK let's have a track walk now!!!
  • + 1
 XTREME SHOCKZ
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