First Look: 2015 Lapierre DH 39

iceman2058
6/5/2014 4:48am

We knew Lapierre had been working on a brand new design for their new DH bike, and the heavily taped-up prototype we spotted a month ago left little doubt that the "PendBox" suspension system of the previous generation was headed for retirement.

Today, Lapierre unveiled it's new DH to the world, and it's clear that the departure from the old model is complete. The new DH is made from aluminum, sports a single-pivot, linkage-driven suspension platform and rolls on 27.5" wheels. These choices were made by Lapierre's World Cup DH race team after what is said to be extensive testing of multiple options.

Team Lapierre at the Fort William launch of the new DH - photo by Sven Martin.

Whilst he is not riding DH competitively anymore, Nicolas Vouilloz plays a key role in the development of all new gravity and trail bikes at Lapierre (in addition to killing it for Lapierre on the EWS tour!) Sven Martin checked in with Nico at the launch of the new bike in Fort William to hear first hand what were the key elements that went into the design of the new ride - listen in below!

 

2015 Lapierre DH - photo by Dave Trumpore.

A quick glance at the geo chart of the new bike reveals that Lapierre has bucked the recent trend towards longer TT/Reach and short stays - the numbers here appear quite conservative at 445mm for the chainstays and a somewhat short 429mm of reach on the size L. Lapierre does state they they wanted lots of tire clearance which may partially explain the longer stays, although we'd assume handling came first by a mile on the list of criteria behind that choice, as even with 27.5" wheels the chainstays could be a lot shorter. With a slack headangle Lapierre probably also wanted to avoid creating an oiltanker-like wheelbase to ensure that the new bike will remain fun to ride everywhere, which explains the conservative reach measurement.

Gobs of space for the rear tire - photo by Sven Martin.

In terms of suspension, the new platform dubbed "SupraLink Technology" by Lapierre, has been designed to provide good small-bump compliance with a strongly progressive leverage ratio towards the end of the 210mm of travel available. Lapierre says this is a direct response to the ever-rougher tracks and the more aggressive riding style of today.

MX-style linkage for a very progressive leverage ratio curve - photo by Dave Trumpore.

By choosing a single-pivot design and what appears to be a beefy swingarm and a sturdy main pivot construction, Lapierre are aiming for stiffness and strength over the intricacies of a virtual-pivot design. The pivot placement is said to be "DH-specific", which should translate to excellent bump absorption and suspension "neutrality" at the (relative) expense of pure pedaling efficiency. With the pivot very close to the top of the chainring and almost centered over the BB, there are little to no anti-squat characteristics here - anti-squat would typically help pedalling efficiency but would also increase the effect of chain forces on the suspension.

Single-pivot simplicity does not mean that Lapierre cut any corners with their new bike - there are lots of small details on the frame that should all add up to one impressive package. Built-in guards and internal cable routing should help keep the bike quite, while the adjustable head angle will allow riders to dial in their preferred geometry, starting from a very slack 63.7 degrees that is adjustable by 1 degree in either direction.

Lapierre DH Highlights

Certainly a big departure from the PendBox days - photo by Dave Trumpore.

  • Single-pivot kinematics specifically developed for downhill.
  • 210 mm of travel.
  • A suspension curve that maximizes sensitivity on small shocks and becomes ultra-progressive at the end of the travel to avoid bottoming out.
  • A unique linkage system for an optimal suspension curve.
  • A main pivot point position that limits the impact of pedaling on the suspension.
  • New oversized axles inspired by OST+ for increased stiffness, better reliability and easy maintenance.
  • New removable compact rear dropouts.
  • Simplified internal cable routing.
  • Adjustable head angle (63,7° +/- 1).
  • Conical headset for greater stiffness.
  • Wide clearance of the rear wheel for better mud clearance and more freedom in tyre choice.
  • New chainstay and seatstay protections, rubber protection for the pivot (from chain slap).
  • Fork bumpers on the downtube.
  • New rear mudguard.
  • Available in October, pricing TBA.

Ready to roll - photo by Dave Trumpore.

Lapierre DH Geometry

Build Kits

The build kits are DH-specific, with a BoXXer Air/Vivid Coil combo on the Team version and a BoXXer Coil/FOX Van combo on the 727. Both versions get SRAM's X01 DH transmission, with a 7-speed rear cluster for the Team and a 10-speed version on the 727. The Team version gets the full Easton Havoc treatment including wheels, while the 727 turns to e*thirteen for rims and cranks. Schwalbe's Magic Mary rubbers are mounted on both versions in UST form.

DH Team

  • Frame: DH Alloy Supreme 6 MULTIBUTTED 210mm Rear Travel
  • Fork: ROCK SHOX BOXXER WC FAST Solo Air 27.5’’ 200mm - Short crown - Gravity logo
  • Shock: ROCK SHOX VIVID COIL 240x76
  • Rear Derailleur: SRAM X01 DH SHORT CAGE 7-SPEED
  • Components: EASTON HAVOC
  • Saddle: SDG CIRCUIT TI DH
  • Rims: EASTON HAVOC 27.5’’ 20x110 / 15x150 XDriver
  • Tyres: SCHWALBE MAGIC MARY UST 27.5x2.35 VSC Front / TSC Rear

DH 727

  • Frame: DH Alloy Supreme 6 MULTIBUTTED 210mm Rear Travel
  • Fork: ROCK SHOX BOXXER COIL 27.5’’200mm - Short crown - Gravity logo
  • Shock: FOX VAN R COIL 240x76
  • Rear Derailleur: SRAM X01 DH SHORT CAGE 10-SPEED RED
  • Components: EASTON HAVOC
  • Saddle: SDG CIRCUIT TI DH
  • Rims: E13 LG1+ EXALITE 23C 32H 27.5’’
  • Tyres: SCHWALBE MAGIC MARY UST 27.5x2.35 VSC Front / TSC Rear

The new DH will be available in October, pricing yet TBA.

Catch the Bonus Gallery from the launch of the bike at Fort William, courtesy of Sven Martin.

More information at: www.lapierrebicycles.com

Photos by Dave Trumpore and Sven Martin.

Related:
First Look
Lapierre
Downhill
39 comments

View replies to: First Look: 2015 Lapierre DH

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kc358
10 years ago
It's funny how much money goes into the marketing of Horst link, VPP, PendBox, etc. type suspension systems to convince the public how much better they are only for them to be replaced and outperformed by a simple single pivot design. The simplicity of a single pivot just plain works. That's why you gotta like brands like Foes for sticking with it and showing that it still works better than those fancy four-bar designs. All the four-bar designs do is compromise ride quality and bump absorption to reduce pedal bob, if they even do much to reduce pedal bob.
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Primoz
10 years ago
It's not as simple as that. You can achieve similar anti-squat characteristics to a single pivot with a 4-bar design (be it horst link, VPP or any other simmilar design, it's all the same, you still have 4 pieces rotating around) with less disadvantages, related to brake squat and pedal kickback (it could turn out that the correct position of the pivot would cause massive pedal kickback, which isn't that much of a problem on a DH bike though).

Also a 4-bar design is stiffer, since it has connecting pieces, though that can be mitigated with the use of linkage driven shocks, like in the case of Kona. But still. When it comes to all mountain bikes and the like, pedal efficiency is, in my oppinion, paramount. After all, you spend over an hour pedaling the damn thing up and blast down in 10 minutes. I'd say the benefits of less pedal bob for a bit worse bump absorbtion (though with modern shocks, geometry and 160 mm and the like of travel, is that really such a problem?) are worth a lot more.
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kc358
10 years ago
As I said, 4-bar simply compromise one area (bump absorption) to gain in another (anti-squat). Single pivots are actually stiffer. Every pivot adds a place for flex, single pivots have one less flex spot. As most single pivot bikes use linkage driven shocks, or just use linkages for stiffness (see Foes) they have as many frame contact points and still less pivots, so less flex.

I guess I have a different opinion as you, I'd rather give up slight, unnoticeable pedal bob to gain better suspension performance when not only descending but climbing (small bump absorption allows the wheels to track over rocks and roots without robbing momentum and making it uncomfortable to me).

So, like I said in my first comment, it is funny how millions of dollars can be spent on marketing to convince people that 4-bar is better, yet look how many are still single pivot.
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Primoz
10 years ago
Yet look at how many previously single pivots have gone the FSR route now that the patent has expired.

Also, i read your comment, there is no possible way for me to have a straight face and all i can say to you is 'do you want to ride my banana swingarm Commencal Meta 5.5 from 2008'? It's a linkage driven single pivot and has, like you said, 'as many contact points as an FSR'. Yet the thing flexes like it's made of bubblegum.

The pivot in itself doesn't flex that much, since thick walls are used in the part, that is either CNC'd or forged. Be it the 'dropout' itself (the bearing hole on the frame) or the link. Sure, the bearing has some clearance, it has to to move properly. But it's in the order of the hundreds of a mm, so it doesn't even jump around like it does when a bearing is shot.

You can make a single pivot stiff by triangulating it, like this Lapierre does. But every time you will go this route, you will have stiffness problems. It's quite known that Oranges for example put a lot more stress on the shock. You can always go the Kona route, which i would prefer, but once there, why not go the FSR route that opens up a whole new world of possibilities?
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kc358
10 years ago
Everything is give and take. Links will naturally have more flex. How do you remove that flex? Make them stronger which means more weight. So when it comes down to it, A triangulated 3 link is going to be either stiffer or lighter than a triangulated 4-link. Yes, crappy designs can exist, but that's true for both ways.
Again, the only thing that 4-bar systems have done is remove small bump compliancy for some anti-bob. I ride my bikes for the downhill, not the uphill, that's just how I have to get there. I'll take a suspension design that performs well on the fun part than one that is uncomfortable the whole time for minor efficiency uphill.
If 4-bar is so much better, why did Lapierre drop it after all their marketing of the advantages for a single pivot?
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Primoz
10 years ago
As far as i can tell, the Zesty and Spicy models still use a 4-bar. Also, a 'triangulated 3-link' is jut that, a triangle. It doesn't move.

Personally i prefer to have a bit more eficiency in the hour+part of the ride compared to something a bit better in the 10 minute part. I'm riding around on a flexy 2008 Meta 5.5 with a completely outdated geometry (68° HA i think), but riding is still fun like hell and i'm still quite a lot faster than a lot of the guys on much newer machinery. The bikes are in most cases a lot more capable than the riders are.
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DavidG
10 years ago
Virtual pivot point systems nowadays are actually the most rigid, or the potentially most rigid designs. Because you basically have a one-piece rear triangle like on a single pivot, but which is connected to the frame not only on one place but on two. There is an extra link on each of those connections instead of a direct attachment like on a single pivot frame but it's usually a short and stout one that doesn't introduce extra flex into the system. I have seen some vpp systems that don't use the one piece rear triangle but most of them do. It's true that four bar linkage systems must be really well executed to be as rigid as the one piece rear triangle ones, the latest Demo bike seems to have accomplished that with large bearings/pivots and a direct connection to the bottom bracket of the main one.
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Primoz
10 years ago
A VPP that doesn't have a one piece triangle is just impossible.

I'd say a double short link (VPP, maestro, DW link, etc.) would be less stiff than an FSR setup, since it has a pair of bearing/pivots closely together. If you have a tolerance in the order of hundreths of a mm, you get a small angle change, when loaded sideways. Even a small angle will give a lot more deflection over a long distance. And that's the thing, short link setups have a long lever from the bearing to the axle, while FSR has one of the bearings closer to the axle.

That and a single pivot/FSR setup can usually be made quite a bit shorter/more compact in the chainstay area.
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DavidG
10 years ago
It's true that double the bearings equals to double the bearing "play", but there is another, crucial factor here, which is the width of the pivots themselves. A pivot located immediately behind the bottom bracket can be as wide as the bb itself, usually it has an axle with bearings at each end. This is also why pivot bearing play on single pivot bikes is usually not noticeable at all. The pivots of a fsr setup on the other hand are only about a centimeter wide. They are far from the bb but are close to the wheel axle, which is a major source of flex on fsr systems. This is also why through-axle hub fixation systems are particularly helpful for fsr. As for vpp without a one piece triangle, just look at the original vpp design implemented on the Outland VPP frame, before Outland sold the patent to Santa Cruz, which then re-created it with the single piece rear triangle.
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DavidG
10 years ago
There is also at least another vpp bike which has an additional linkage insted of a rear triangle, maybe a Marin or something.
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Primoz
10 years ago
Is that even a VPP since all of the links, if i get the design correctly, rotate in the same direction?

Bearing play isn't noticable on any bike, as long as the bearings are okay. And to be exact, the pivot on a FSR by the axle is spaced ~150 mm apart. The problem is that the two sides aren't connected as tightly as they are down by the BB.
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DavidG
10 years ago
The Outland IS the original VPP, how can you ask if it is even a vpp? It was a FSR-type design but in which the chain stay was linked to the bottom bracket with two extra links which created a virtual pivot point (VPP). Santa Cruz then switched the fsr type design for a unified rear triangle, and relocated those two links. But it's still a vpp system, where the wheel's pivot point is virtual and defined by the size and location of those two links.
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Primoz
10 years ago
I was under the impression that a defining feature of the VPP is the counter-rotating links. If it's just a virtual pivot point, VPP is not the only 'VPP' system out there. After all, FSR does also have a virtual pivot point
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DavidG
10 years ago
Yes that's true... But fsr has a typical chainstay directly connected to a pivot point on the frame, which vpp doesn't. And neither did the Outland.
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Primoz
10 years ago
Using the term chainstay is a bit arbitrary maybe. Look at the Wilson, it's a single pivot, yet the chainstay, as is otherwise the norm, is not actually the swingarm.

But yeah, i get the point. It's actually an interesting design, albeit a complicated one tat has way too many pivots to be practical.
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DavidG
10 years ago
In the case of the Wilson, like it happened with the GT RTS for example, the chainstays are not directly connected to the frame but the seatstays are, and their pivot point on the frame is the precise pivot point of the rear wheel, which is also what defines it as a single pivot type design even if there are other pivots and linkages. It's true that any non-single pivot type design ends up having a virtual pivot point for the wheel's path. But it shouldn't be difficult to identify a so-called "vpp" design, the outland's design isn't that different from the current vpp in that the rear wheel's path is still defined by two links near the frame, both connected to a single piece to which the wheel is attached. In the old design this piece was the chainstays, on the current one the chainstays transformed into a rear triangle, the links changed location and the shock became actuated not by a four bar linkage (two parts of which, along with the corresponding pivots, were discarded) but by one of the links itself.
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Primoz
10 years ago
"With the pivot very close to the top of the chainring and almost centered over the BB, there are little to no anti-squat characteristics here"

Care to elaborate this part of the article?
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iceman2058
10 years ago
Anti-squat refers to chain tension contributing to stiffening up a suspension system, i.e. when you get on the pedals, the force on the chain causes the rear suspension to extend. This is in general good for power transfer, but not good for isolating pedaling forces from the suspension. On a bike with a lot of anti-squat, you can feel the rear wheel through the pedals, especially when on the brakes or when powering through rough terrain. Anti-squat comes from the chain being placed at an angle to the main forward pivot of a suspension system, on a single pivot (like this Lapierre) that is achieved by placing the main pivot above the top of the chain ring.

On this bike, Lapierre have opted for a main pivot placement that doesn't create a lot of anti-squat, to let the suspension do its work in isolation from the pedaling forces.
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Primoz
10 years ago
The pivot is actually lower than the top of the chainring, which would mean it's actually pro-squat when on the power. Though you do have to take into account the force between the tire and the ground, which can also contribute some anti-squat (it is the main component of the high pivot bikes actually, Zerode for example). The height of the pivot is the crucial part, since it gives the chain the torque needed to rotate the suspension. Fore/aft placement doesn't mean much, when looking at the suspension in a single point (sag for example), though that can change wildly when the suspension is going through the travel (the pivot-to-BB, the chain and the swing arm forming a triangle - the lower the triangle, meaning the three points are basicly inline, the less anti-squat you have).

EDIT: ofcourse i thought it through too quickly and changed my oppinion before. It's actually the pivot to BB height that's important, since a concentric pivot means no change in the chainstay lenght, thus giving you zero available work from the chain force. Raising the pivot means the chainstay length increases, thus giving you antisquat through the chain force.

The question here is the role of the size of the chainring. As far as i can tell, you input an X ammount of watts into the system via the cranks, which is then transformed into the chain force. The larger the sprocket, the less force you have (and less anti-squat then). I might be missing something, but i don't see a way you could transfer the force directly through the chain from one sprocket to the other and not through the suspension system.
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iceman2058
10 years ago
The height of the pivot (virtual or not, BTW) relative to the top of the chainring is a direct factor influencing anti-squat. The size of the chainring will therefore play a role, yes - the smaller the ring, the more torque will be created as a result of the force along the chain, because it will be pulling on the rear wheel at a more open angle (coincidentally, it will also give you more power on the chain because of better leverage from the pedals, so the effect actually amplifies with a small chain ring). And of course, this happens in conjunction with other forces affecting the suspension system as a whole (the force of your weight pushing down on the bike as you pedal, the force of the rear wheel pushing on the ground, etc).

As for your last question, if there is no offset between the chain force and the main forward suspension pivot of a suspension system (i.e. the chain force acting on the main pivot at an angle), there will be no anti (or pro) squat as a result of chain forces. Of course, not many suspension systems would exhibit this characteristic throughout the whole travel. For example, Lapierre's previous suspension system ("Pendbox") attempted to combine both pro and anti-squat characteristics on either side of the sag point, to basically always use chain forces to push the suspension back towards the sag point. Whenever on the power, the chain would draw the suspension back towards the sag point, regardless of whether the bike was heavily weighted or not. They obviously felt that simpler was a better way forward here since they've abandoned the concept completely.
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Primoz
10 years ago
There ofcourse is the chainforce even with a concentric BB pivot, but it has no lever, path, travel, etc., to act upon. Therefore it does no work (W=F*s and all, s being zero means W is zero).
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DavidG
10 years ago
I think you have some concepts wrong here. A concentric BB pivot is all but neutral regarding the influence of pedaling on the suspension. What matters is only where the suspension pivot stands in relation to the line of force, and the line of force is the chain line from the top of whatever cog it is in to the top of the chainring. If the pivot stands along this line, or in the virtual continuation of it, then pedaling has no influence on the suspension. If it is above the line, pedaling will extend the suspension (the so-called anti-squat), if it is below it will compress it (squatting). All these effects can be experienced with a triple ring crankset on a frame whose pivot is aligned with the middle ring chain line. On the small ring you will have some anti-squat action which will give you some extra traction on the hills, on the middle one the effect will be neutral (my favorite, since that is where the biggest percentage of the pedaling force is converted to forward motion), on the big ring pedaling will create squatting, which is totally undesirable and the main drawback of single pivot bikes. Of course the pivot could be placed higher, but then the anti-squatting action on the smaller rings becomes too pronounced. Or a shock with a platform system could be used, to lock the suspension when triggered by pedal forces. Regarding the more or less forward placement of the pivot in relation to the BB, a more forward placement will provide a more vertical wheel path due to the bigger rear wheel axle radius, which is an advantage, and it will create the effect that as the suspension is compressed, pedaling influence will change from neutral to anti-squat, which I don't think brings any advantage but it is not so harmful either, and the more vertical wheel path may well make up for it. As for why the pivot on this bike is so low, I really don't know since unless a really small chainring is used there is no advantage to it, but it could simply be a sacrifice made to other factors, like the placement of the shock or the shock linkages or something else...
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Primoz
10 years ago
David your first sentence is mistaken. A concentric BB pivot actually does NOT affect the suspension. Yes, it bobs like hell, but that is not because of the chain forces themselves. It's because of the inertia of the body and it's high position. It doesn't want to accelerate, when the bike under the rider does. So the whole system (rider+bike) rotates around the centre of gravity, meaning the bikes lunges forwards, compressing the rear suspension (the CoG of the rider wants to move as steadily as possible, so ~constant velocity, and ~constant height).

If you want to get rid of the bobbing, you NEED the influence of the pedaling via the chain. That's why you don't have a concentric pivot. The level of antisquat, which we are talking about here, differs greatly between the granny, the middle and the big ring on a tripple, luckily for the MTB world it more or less adds up with the needed level of antisquat (the least is needed and produced in the big ring and the opposite for the granny), which made the first full sussers actually work. Who knows what we would be riding now if we first got 11spd drivetrains an full sussers after that.

Think about it properly, it has all to do with the energy. No difference in the chainstay length with a concentric pivot means no work can be done by the pedaling via the chain on the suspension system, which means it doesn't affect it at all. Move the pivot up and you get anti-squat. Move it down and you get pro-squat. This is of course in isolation, as said you still get some anti-squat from the tire-to-ground forces. It's all a great balancing act.
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DavidG
10 years ago
"A concentric BB pivot actually does NOT affect the suspension. Yes, it bobs like hell, but that is not because of the chain forces themselves. It's because of the inertia of the body and it's high position."

Wrong. What affects the suspension is the chain force, not the bottom bracket placement. The bottom bracket could be anywhere and the force be transmitted through a secondary chain, it doesn't matter. A bb-concentric suspension pivot squats a lot because it stands much lower than the chain line, that's all. The farther the chain line is from the rear triangle pivot, the easier it is for the chain to pull it.

"No difference in the chainstay length with a concentric pivot means no work can be done by the pedaling via the chain on the suspension system, which means it doesn't affect it at all."

Not true at all. The chainstay is always of a fixed or variable value, depending on how you are measuring it, and regardless of whether it is concentric with the bb or not. The degree to which the chain force produces work on the suspension depends only on how far it is from the rear triangle pivot.

You are wallowing on some misguided and incomplete concepts when only one thing matters to determine suspension interference, which is the relationship between the chain line, which determines the origin of the force, and the suspension pivot. Of course that the body weight can also conteract some of these interactions but the primal factor is that which I have been mentioning. The fact that using different chainring sizes makes so much difference demonstrates that the chainline is a crucial factor regarding pedaling/suspension interference.
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iceman2058
10 years ago
Primoz, David is right here. The "work" that you are talking about a few posts above actually DOES have somewhere to go - into the shock. ON a BB-concentric system (rare as they are!), when the rear wheel is in contact with the ground, your pedal basically becomes a lever to directly compress the suspension. The whole system pivots around the BB and when the chain can't move anymore (because the bike can't accelerate faster), it will make the whole thing rotate around itself.

All these concepts are all pretty confusing and the devil is definitely in the detail, which is why there is so much development time dedicated to suspension in general, and why guys like Weagle and co are so involved in bike design.
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Primoz
10 years ago
Whoa, my concepts are incomplete? I am actually the one that looks at the whole system, not just the force or two actoing around the chain. THat's why i can say a concentric BB pivot has no affect on the suspension, yet it still bobs. Because the complete concept brings the bobbing in from other places. Th view you two have (the devil in the details and all) just means that looking at the suspension in isolation and all, the antisquat from the chain would make the suspension extend. Yet it doesn't, if it's properly designed. Because complete concept.

Again, in the case of a concentric pivot the distance between the pivot (or B and the rear axle does not change at all. So zero 'travel' and zero work can be done by the chain. If there is zero work, there is zero effect. When you move the pivot up, the distance between the BB and the axle lengthens when you go through the travel. Thus the chain force can do some anti squat work, since it does have some travel to work against (the work is not zero).

The problem with bobbing is that you press on the pedals about 3 times a second and let up in between each press. Which gives you an oscillating force. The force is then transmitted to the ground through the tire, where the actual accelerating force is acting. But the CoG is high up, in the middle of your torso. So the accelerating force has about a meter of a lever tot he point it is acting on.

Now Newton said that a body is stationary or moving at a constant velocity, if the forces on it are equal to zero. He was wrong. Moments also need to be zero, otherwise the object can just spin up (sure, the CoG will be stationary, but te body will rotate around it, thus still getting more and more rotational energy).

This is the case here, the forces and moments are not zero, the accelerating force wants to rate the rider around. Basicly trying to make a wheelie. And of course the weight transfer squats the suspension. That's why a concentric BB pivot squats like hell. While antisquat means that the bike rides like it should, the system just got completed.

Yes, you cna have an idler pulley. But if the idler will be concentric with the pivot, it's just the same. The chain itself does exactly zero anti-squat work. But you get quite a lot more antisquat from the tire force itself, which is another component of the antisquat and needs to be taken into account too (incomplete systems and all again). A bike like a Zerode needs a lot less antisquat from the chain becuase it has the pivot so high up.

EDIT: "What affects the suspension is the chain force, not the bottom bracket placement."
Nobody said nothing about BB placement. And yes, you can have idler pulleys and all, but i covered those. But since the vast majority of the bikes has only one chain, i think it's just nitpicking then. But no problem, i can cover those concepts as well.

"Not true at all. The chainstay is always of a fixed or variable value, depending on how you are measuring it, and regardless of whether it is concentric with the bb or not."
So you basicly covered all the scenarios possible. Good. What's the point? Ofcourse it can be either fixed (hardtail, concentric BB pivot) or variable (all other full sussers), there is no other option. And by chainstay i mean the BB to rear axle distance.
"The degree to which the chain force produces work on the suspension depends only on how far it is from the rear triangle pivot."
How far what is from the triangle pivot?
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iceman2058
10 years ago
Primoz, try this: if you remove the shock from a BB-concentric single pivot bike, then lock the rear wheel, then turn the pedals - what will happen?
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Primoz
10 years ago
Something is supposed to happen, but that's an edge case. If you don't lock the wheel, you have it on a bearing. So it can only tranfer forces perpendicular to the bearing. Meaning through the swingarm (rear axle to the pivot). Any part of a force, that is not perpendicular to the bearing, will just cause the wheel to rotate. So accelerate the bike
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iceman2058
10 years ago
BUT once the wheel is in contact with the ground, and the bike can't accelerate any faster, part of the force from the pedals will now go into compressing the shock instead of creating forward momentum. The wheel is ALWAYS on bearings, in any system.
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DavidG
10 years ago
Think of a pole that is laying on the ground. One end is tied to a fixed point on the ground, another end is tied to a rope with approximately the same length as the pole. The analogy is that the pole is the chainstay, the rope is the chain and the end that is tied to the ground is the pivot. If you pull the rope alongside the pole, all the force will be converted to a compression force on the pole, against the point that is tied to the ground. There will be no actual "work" done. If you raise the rope slightly, you will be able to pull the pole, but it will require a lot of force since most of it will still be turned to a compression force on the pole. The higher you raise the rope when pulling it, the least compression force you will have to work against, and the easier it will be to raise the pole.
So by this analogy, "How far what is from the triangle pivot?" Your hand, pushing the rope. Your hand is the chainring, pushing the rope/chain. The higher you are when pushing it, the more of your force will be transferred to the shock instead of being turned into compression force against the suspension pivot. When all of the energy from the chain is turned into compression force against the pivot (thus being 100% transferred into pulling the cogs) is when independence exists between the pedaling force and the suspension.
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Primoz
10 years ago
David your analogy is good. But the tied down part of the pole is the pivot, the other part is the rear axle and the rope is the BB to axle line.
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DavidG
10 years ago
No, the rope is the chain. The chain IS the pedaling force. The bb has nothing to do with this. Going by the analogy, the bb is your feet, and your hands are the edge of the chainring that is pulling the chain. It doesn't really matter how high or low you place your feet, as far as the effects on the rope and pole are concerned.
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DavidG
10 years ago
Nice stout single pivot, looks great too. Never been a fan of black but this one does the part.
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orion98
10 years ago
now the question is ... how can a 16 yerar old get one fo free?
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onenerdykid*
10 years ago
on paper, a lot of the geometry seems really odd... but I like that the new XO DH will be available in 10 spd!
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nuro
10 years ago
what the hell is this.. ugly as sin...lapierre is going to drown with this s..t
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