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funky new lahar (carbon exoticness)

Bicyclist

Turbo Monkey
Apr 4, 2004
10,152
2
SB
SlackBoy said:
Perhaps you just don't ride fast enuff
The design man hisself
You're right. I don't think I'd actually be able to utilize a 62 HA. But the bikes still are the coolest thing I've ever seen! :drool:
 

bballe336

Turbo Monkey
Mar 3, 2005
1,757
0
MA
Bicyclist said:
You're right. I don't think I'd actually be able to utilize a 62 HA. But the bikes still are the coolest thing I've ever seen! :drool:
Very few people would be able to utilize a HA that slack. I have to tell you that even if I was much faster than I am I would still want a steeper HA. In tech sections that could become sketchy.

But the bike is still the sexiest thing I have ever seen.
 

Punter

Chimp
May 8, 2006
54
0
bballe336 said:
Very few people would be able to utilize a HA that slack. I have to tell you that even if I was much faster than I am I would still want a steeper HA. In tech sections that could become sketchy.

But the bike is still the sexiest thing I have ever seen.
A girl who races in NZ got off her DH Comp and got on one of these.
She now hates her DH comp and is buying a Lahar complete with 63deg HA.

This bike is designed to be raced at the highest level. So maybe it wont suit some people. Although this girl loved it......
 

habitatxskate

blah blah blah
Mar 22, 2005
943
0
i would never be able to ride it..i think i would fly away if i ever hit a jump..i love my heavy ass faith 3..it weights 55 about, and i weigh 110...doesn't bother me..i'd be afraid to ride that since the rear triangle seems super thin, although it is probably super strong though..don't get me wrong, if someone offered to give me it, i'd be like K
 

bballe336

Turbo Monkey
Mar 3, 2005
1,757
0
MA
habitatxskate said:
i would never be able to ride it..i think i would fly away if i ever hit a jump..i love my heavy ass faith 3..it weights 55 about, and i weigh 110...doesn't bother me..i'd be afraid to ride that since the rear triangle seems super thin, although it is probably super strong though..don't get me wrong, if someone offered to give me it, i'd be like K
How did you get a faith 3 to weigh 55 pounds? They are like 47 stock with really heavy parts.
 

habitatxskate

blah blah blah
Mar 22, 2005
943
0
i got a huge ass seat, lioke a foot long, chainguide/e13 bash guard too..and some other random crap..its an estimate..plus the stronger tubes and heavier front tire..its an estimate..weight doesn't bother me..who's punter? like i said, its probably super sturdy, but i'd be afraid, i'm a bitch like that.
 

JohnnyC

Monkey
Feb 10, 2006
399
1
Rotorua, New Zealand
Bicyclist said:
Who's Punter?
The guy who's been posting on the last couple of pages?

The guy who's broken more mainstream downhill frames than you've had cooked dinners -bar one- the lahar and its had 7 seasons

Also finished 5th in the 3rd round of our national series after crashing in the race run and breaking his foot. So any bike that can stand up to him has got to be good. Another local rider is just as rough and his one is still going hard. The first of the new models was ridden into a tree at mach 1 by a 100kg rider, destroying the front wheel and blowing the fox 40 cartridge to pieces but the bike didn't get a scratch. The lahar wastes every other bike in every way and look out for them on this years race circuit!
 

LaharDesign

Monkey
Jun 16, 2006
159
0
The guys confused about the head angle are missing an important fact.
on conventional bikes when you load up the suspension in a corner your verticle rear wheelpath transfers your weight onto the back wheel encoraging understeer of the front. The Lahar has parallel wheelpaths that don't affect weight distribution in cornering or over bumps.
 

LaharDesign

Monkey
Jun 16, 2006
159
0
Where we are...

The 6 mark 8 bikes built in 2002 are all still racing under podium pros and 2 of them have just been loaned by their owners for the next years racing to the 2 top u17 riders in the country, Pete Cooper and Dave Scandrett. The m8s have endured up to 7 pro seasons each under serious bike breakers like Mark Johnston who says he never had a crmo bike last longer than 2 mths(his is the m8 #1, raced by byron scott, tim nelson, mark johnston, wyn masters,mark johnston, darryl web, mark johnston, david scandrett) .:)

The mark 8 bikes are still considered by all who try them - and we're talking most of NZ's elite riders to be well in advance of leading conventional bikes in the market today. The m9 is considered better than the m8 in every way.

Indisputable evidence of race advantage was achieved in the 2003 nz national season when a team of 2 pro's, 1 junior and 1 master were unbeaten by any other bike in the whole national series. The margins were huge and every elite rider to complete a race season on a m8 received a letter from the uci "due to an unusually abrubt increase in race performance you have been selected by the uci's computers as a potential drug cheat" and were placed on drug report.
If the mark 8 production molds had not vanished from a subcontractors at the end of the 03 season you would have heard a lot more about Lahar.:nopity:
Happily we now have a new company, new m9 bike and new production molds.:dancing: Indications are that we have a dominant market demand in the NZ core scene in the upcoming season.
 

LaharDesign

Monkey
Jun 16, 2006
159
0
Lahar DHV m9 Price list june 06

Item US price $US

Lahar DHV m9 Frameset incl fox dhx5.0 $2,476.07

Lahar dhv Drivetrain kit incl: Rohloff,
Chains, RaceFace xtype diabolus crank,
Freewheel, Carbon barrel rear hub.
Chainring, bashguard. $1,317.94

spare rear or front carbon barrel hub $128.45
Freight to u is US$200
 

LaharDesign

Monkey
Jun 16, 2006
159
0
Actually I should warn you that I can't sustain that introductory price for long. I'm getting a lot of distributor enquiries and they all want the price raised. Australian and european prices are already up due to this.
I sold one of the m8's to a californian for US$9000 in 2002, so obviously we're running much tighter margins this time round.
remember theres over 40 hrs of skilled labour and 10x the materials cost in one of these beasts so the only way to offer them competitively is by slashing marketing costs. Fortunately the bikes rep travels far and its excellence therefore allows profitability.
 

Bicyclist

Turbo Monkey
Apr 4, 2004
10,152
2
SB
Trust me, I wish I could afford it. Unfortunately I work at a shop so I get deals on their bikes anyways and my wage isn't that big. I wish it was.
 

LaharDesign

Monkey
Jun 16, 2006
159
0
habitatxskate said:
i would never be able to ride it..i think i would fly away if i ever hit a jump..i love my heavy ass faith 3..it weights 55 about, and i weigh 110...doesn't bother me..i'd be afraid to ride that since the rear triangle seems super thin, although it is probably super strong though..don't get me wrong, if someone offered to give me it, i'd be like K
The rear triangle is the strongest, stiffest and most damage resistant in the world. This is due to solid sections of near identical dimensions to the swingarms of a F1 GP car. Each of the 30mm x 5 mm section lower stays has a tensile strength of ~20 tons. Conventional metal stays are usually around 2 tons sectional strength but are heavily compromised from this by welds.
:cool:
 

frznnomad

Turbo Monkey
Jun 20, 2005
2,226
0
a-town biatches
man im sure that your frames have one hell of a badass guarentee but i dont know about all of this carbon i just cant trust it. there are so many things that could go wrong on a dh run and so many things that can go wrong with carbon i just dont know about it. is there anything you can give us besides a writen guarntee that could prove all of this. im sorry to be such a sceptic but i just like my alluminum dh rig.
 

LaharDesign

Monkey
Jun 16, 2006
159
0
frznnomad said:
man im sure that your frames have one hell of a badass guarentee but i dont know about all of this carbon i just cant trust it. there are so many things that could go wrong on a dh run and so many things that can go wrong with carbon i just dont know about it. is there anything you can give us besides a writen guarntee that could prove all of this. im sorry to be such a sceptic but i just like my alluminum dh rig.
Man, I have built plenty of Al and CroMo bikes. The reason I stopped is because of a little thing called metal fatigue. Provided you know how to take advantage of carbons properties and don't use cheap technologies like Thermoplastic carbon, you can achieve up to 40x the strength/ weight of the best metals. Carbon doesn't wear out if its strong enough and damage resistance and tolerance are much better than metals.
Pros often go through several alloy frames a season. NZ's most destructive and crashingest pro's 4 x NZ#1's among them have been unable to damage these bikes over ~300 races, ~1000 bad crashes including things like "bike off cliff onto rocks". We've had bikes doing dual hemisphere racing since 2001 and none have failed!
:rofl:
 

Bicyclist

Turbo Monkey
Apr 4, 2004
10,152
2
SB
frznnomad said:
man im sure that your frames have one hell of a badass guarentee but i dont know about all of this carbon i just cant trust it. there are so many things that could go wrong on a dh run and so many things that can go wrong with carbon i just dont know about it. is there anything you can give us besides a writen guarntee that could prove all of this. im sorry to be such a sceptic but i just like my alluminum dh rig.
When built right (like this bike is) carbon is practically indestructible. I was a skeptic at one point too but the science of the matter is carbon is a super-material when properly used.
 

frznnomad

Turbo Monkey
Jun 20, 2005
2,226
0
a-town biatches
okay if you say so. i mean yes it is strong, light, and very stiff. the only thing that has me worried is the internal stregth of the carbon and if its like the carbon bars and seatpost out there. if it gets a gauge and breaks threw the clear coat replace it cause it will break, and i dont like that little fact. but that is just me
 

LaharDesign

Monkey
Jun 16, 2006
159
0
frznnomad said:
okay if you say so. i mean yes it is strong, light, and very stiff. the only thing that has me worried is the internal stregth of the carbon and if its like the carbon bars and seatpost out there. if it gets a gauge and breaks threw the clear coat replace it cause it will break, and i dont like that little fact. but that is just me
:rolleyes:
Mate thats bull biscuts!
Carbon in a high performance epoxy matrix is extremely damage tolerant. If you do succeed in taking even a big chunk out of the frame(no one has) the damage won't spread unless you exceed the strength of whats remaining. And you could repair it in 10 min to above original spec.
I'm not bagging the experiences many people have had with mass produced thermoplastic or polyester carbon product as these have no bond with the carbon and delaminate easily. As can rolled prepregs for that matter, like most tubular structures.

Its been a good 5 years since I've had to convince anyone in this country. My practice of sponsoring the best bike breakers from the pros did the deal. :cool:
 

LaharDesign

Monkey
Jun 16, 2006
159
0
syadasti said:
I was talking about the GT IT1, not the Lahar. Try reading next time :rolleyes:
my bumbleheaded appleogies.

I saw one of those in a local bike shop the other day. It hasn't changed a lot since they copied me in 97. (my nexus7 speed DHV mark 1 was tested and photoed in NZBike mag who sent 15 copies to GT internat HQ (standard to advertisers), a year later they turn up with their version.:rofl: )
I think they're pitching it as a freeride cause the cheap commuter hub won't handle racing.
And why the heck has it got such a low pivot. Alex BCD will back me on this I'm sure. The design community's pretty final that independant drive with a wheelpath near parallel to the front works best.
Nicholai and Honda have made the same mistake and it would be crap if the market decided that gearboxes were hype just because these three get it wrong.
?Minnars conservatisim?sramPaying off Nicholai?lack of sufficient prototyping?GT seeing more profit in the disposable status quo?
Anyone:
 

syadasti

i heart mac
Apr 15, 2002
12,690
290
VT
Yah thats exactly what I said, who wants a bike from 1997 in 2005/6. Tama pimped the bike a lot though :oink:
 

EVRAC

Monkey
Jun 21, 2004
757
19
Port Coquitlam, B.C., Canada
LaharDesign said:
And why the heck has it got such a low pivot. Alex BCD will back me on this I'm sure. The design community's pretty final that independant drive with a wheelpath near parallel to the front works best.
Nicholai and Honda have made the same mistake and it would be crap if the market decided that gearboxes were hype just because these three get it wrong.
?Minnars conservatisim?sramPaying off Nicholai?lack of sufficient prototyping?GT seeing more profit in the disposable status quo?
Anyone:
Forgive me if I'm wrong, but it looks like the proposed G-CON mounting standard includes a high pivot, very similar to that of a BCD bike. GT's is also quite high.

?
 

LaharDesign

Monkey
Jun 16, 2006
159
0
EVRAC said:
Forgive me if I'm wrong, but it looks like the proposed G-CON mounting standard includes a high pivot, very similar to that of a BCD bike. GT's is also quite high.

?
Fraid not. GT and gcon both run gearboxes forward of the bb and low drive outputs.
G-Boxx gives you a swingarm halfway to the horizontal from what I run and Alex's idler-gear bikes are simular to mine. Havent seen his cogbox.
GT's is flatter still.
In fact they are little different to many conventional bikes.
Because these and Honda's are using no chain-lockout they will squat far worse than conventional bikes unless the propedal is wound right up.
Lahars need no propedal at all and move not at all under the most brutal pedal mashing and I'd expect the same from BCD's.
Other advantages to the higher pivot is when you hit a square edged bump with your wheelpath near vertical as in conventional bikes, the bump only has to be over 4 inches high before the shocks effective leverage ratio is headed for infinity and over half of the bump impulse energy is transfering back through the swingarm to yank and buck the bike out from under you. :teacher:
 

LaharDesign

Monkey
Jun 16, 2006
159
0
the fact that allmost all of the mainframe mass- gearbox,shock,cranks is contained within 7x7 inches of low and rearward positioning on the dhvs makes for very responsive handling.
an analogy in motorsport would be the ferrari enzo to the turbo skyline of the conv bike. The enzo produces far better cornering, responsiveness, and stability despite the potential for equivalent horsepower from the nissans engine better speed would be inevitable from the enzo.
No-one would enjoy racing the powerful riceburner more than the dialed f1 sampling of the itailian purebreed.:) or real life caning for that matter!
 

ÆX

Turbo Monkey
Sep 8, 2001
4,920
17
NM
about the gearbox positions.

I see it like this. for one they are not in the center of the mass.
Your body sits on your BB, that is where inputs go for bike moving
actions. That is where the weight should be centered as close as
possible.

On pivot heights I try and match the height of the rear pivots arc
to what ever the head angle is. that simple. So the wheelbase stays
as close to possible to the same length.

EDIT:

one more thing i might say on carbon strenght. Like was said you can crash and
scrap into a few layers and still have MILLIONS to back it. the bikes i make; as are
the lahars i would think; are overbuild just for that. now bars and seatposts have the MIN amount of carbon to save weight. the diff in a carbon dh bar VS a XC is just wall thickness, but that is not enough to make something strong.
DIAMETER is what makes carbon shine. strenght faxtor goes way up when when the
diameter goes big. snowball effect.
 

thaflyinfatman

Turbo Monkey
Jul 20, 2002
1,577
0
Victoria
LaharDesign said:
The guys confused about the head angle are missing an important fact.
on conventional bikes when you load up the suspension in a corner your verticle rear wheelpath transfers your weight onto the back wheel encoraging understeer of the front. The Lahar has parallel wheelpaths that don't affect weight distribution in cornering or over bumps.
Ok while you're here, I'm going to take the opportunity to hassle you about a few things, purely for the sake of discussion:

Parallel, rearwards wheelpaths (which they're not exactly, but yes closer than most bikes) DO affect weight distribution under compression - it shifts forwards. The only way to have no change in weight distribution under compression (in corners or over bumps) would be to have geometrically OPPOSED axle paths. That is, the rear suspension axle path tangent is symmetrical, about the centre of mass, to the front suspension axle path tangent, or in some way geometrically calculated (incorporating relative shock rates and spring weights as well as compression damping if you were going to be really anal about it) so that the rear wheel moved in such a way that the ratio of horizontal distances between each wheel, and the centre of mass, remained constant. This is not only impractical, it's pretty useless.

LaharDesign said:
And why the heck has it got such a low pivot. Alex BCD will back me on this I'm sure. The design community's pretty final that independant drive with a wheelpath near parallel to the front works best.
Nicholai and Honda have made the same mistake and it would be crap if the market decided that gearboxes were hype just because these three get it wrong.
?Minnars conservatisim?sramPaying off Nicholai?lack of sufficient prototyping?GT seeing more profit in the disposable status quo?
Anyone:
Independent drive? Care to define that? And if the "design community's pretty final that...", why do so few bikes use extremely rearwards axle paths? I would tend to disagree with that claim. Whilst I am personally a fan of high pivot bikes, I have found that the one drawback of them is that it's harder to weight the rear wheel when pumping hard through a corner, because as you g-out and compress the suspension, you move further from the rear axle.

LaharDesign said:
Fraid not. GT and gcon both run gearboxes forward of the bb and low drive outputs.
G-Boxx gives you a swingarm halfway to the horizontal from what I run and Alex's idler-gear bikes are simular to mine. Havent seen his cogbox.
GT's is flatter still.
In fact they are little different to many conventional bikes.
Because these and Honda's are using no chain-lockout they will squat far worse than conventional bikes unless the propedal is wound right up.
Lahars need no propedal at all and move not at all under the most brutal pedal mashing and I'd expect the same from BCD's.
Other advantages to the higher pivot is when you hit a square edged bump with your wheelpath near vertical as in conventional bikes, the bump only has to be over 4 inches high before the shocks effective leverage ratio is headed for infinity and over half of the bump impulse energy is transfering back through the swingarm to yank and buck the bike out from under you. :teacher:
How does your bike use, in your terms, "chain-lockout", and how does the Honda not? I can't really see too clearly from the pictures, but it does appear as though the output drive centre is quite close to, and forward of, the main pivot, with a chainline running nearly parallel to, and rotating upwards relative to, the swingarm as the suspension compresses. If this is correct, then the vast majority of the anti-squat force in your design will be from the tyre's tractive force, as the vertical and horizontal components of the chain tension will cancel each other out (or close to). As the centre of axle path curvature is both fixed and forwards of the axle, this means that the amount of anti-squat can only DECREASE as the suspension compresses (same as the BCD), and given the variation in sag settings between riders, this means that your claim of no movement under pedalling physically cannot be true, because no two sag settings will produce identical anti-squat characteristics. This is not to say that it will not pedal WELL, only that like all other bikes, it is technically imperfect (to what extent, I'm not going to make claims).

Lahar Website... said:
neutral drive squat and brake dive behavior, brake and drive independance from suspension. The mainstream of mtb rear suspension was then and still is all about attempting to balance a jacking force from the chain with thrust squat inevitable when the rear wheel can get closer to the centre of gravity under power.
What do you mean by neutral drive squat? Do you mean no chain-induced extension or compression force on the suspension, or do you mean no NET extension or compression force exerted on the suspension? And without sounding like too much of a dick... with that floating brake setup, there will actually still be some amount of brake-induced compression. Not that that is necessarily a bad thing, by the looks of it, it would be a relatively small amount and if anything probably only serve to help stabilise the bike and prevent the rear end rising too much as the weight shifts forwards under brakes. I don't know whether this is your intention, but if it is, it wasn't your STATED intention so that's why I brought it up :clue:

Please take care to notice that I'm NOT trying to bag you or your bikes here (I would actually love to take one for a run or two) - only disputing your technical claims (not that yours are worse than the standard bike industry fare). If you can show any of my arguments to be wrong, then I will step down, however I do not believe that you will. I can provide free-body diagrams for any of my own theories/claims that you wish to dispute, if you would like me to.


On a less nerdy note: they do look freaking cool. What's the price in Aussie dollars? And could you please give us the chainstay length (static and sagged), wheelbase (for each size, if applicable), bottom bracket height (static and with 35% or your recommended amount of sag - it looks pretty high to me), and what is the leverage ratio for the shock on there? Looks pretty high as BCD said, but I haven't bothered chucking the numbers in (ahh also complicated by the fact that there isn't a pivot for the chainstays/tension bars, which makes calculations a bit more difficult).
 

LaharDesign

Monkey
Jun 16, 2006
159
0
thaflyinfatman said:
Ok while you're here, I'm going to take the opportunity to hassle you about a few things, purely for the sake of discussion:

Parallel, rearwards wheelpaths (which they're not exactly, but yes closer than most bikes) DO affect weight distribution under compression - it shifts forwards. The only way to have no change in weight distribution under compression (in corners or over bumps) would be to have geometrically OPPOSED axle paths. That is, the rear suspension axle path tangent is symmetrical, about the centre of mass, to the front suspension axle path tangent, or in some way geometrically calculated (incorporating relative shock rates and spring weights as well as compression damping if you were going to be really anal about it) so that the rear wheel moved in such a way that the ratio of horizontal distances between each wheel, and the centre of mass, remained constant. This is not only impractical, it's pretty useless.
My observation here is that going down a hill changes the vector the centre of gravity is acting through. If you are going down a 27deg slope- not particularly steep- then the vector is parallel to wheelpath.
Its a hypothesis that inertia duplicates this effect in corners.
The fact that my bikes have had big wins in flat pedally gravelly races and are considered rails in these conditions leads me to believe that weight transfer forward in cornering is perhaps a good thing. Certainly the dhv series with its extremely high rear sprung/ unsprung weight is not short of rear traction.



[/QUOTE]
Independent drive? Care to define that? And if the "design community's pretty final that...", why do so few bikes use extremely rearwards axle paths? I would tend to disagree with that claim. Whilst I am personally a fan of high pivot bikes, I have found that the one drawback of them is that it's harder to weight the rear wheel when pumping hard through a corner, because as you g-out and compress the suspension, you move further from the rear axle. [/QUOTE]


independant is where drive torque has no +ve or -ve force on the suspension action and suspension doesn't feedback thru drivetrain. I'm anal enough to include inertia squat in this definition, at least for my own use.
By the design community I would say that everyone grounded in chassis design science since the physics were completed around 1900. I'd say most every bike designer who's tested the theory and many more besides. Almost BD's will admit it privately though sometimes their commercial obligations prevent public statement. Certainly anyone who's been near motorised suspension has no illusions.
I'm not saying geometry for these bikes should be identical to conv's anyway.



[/QUOTE]How does your bike use, in your terms, "chain-lockout", and how does the Honda not? I can't really see too clearly from the pictures, but it does appear as though the output drive centre is quite close to, and forward of, the main pivot, with a chainline running nearly parallel to, and rotating upwards relative to, the swingarm as the suspension compresses. If this is correct, then the vast majority of the anti-squat force in your design will be from the tyre's tractive force, as the vertical and horizontal components of the chain tension will cancel each other out (or close to). As the centre of axle path curvature is both fixed and forwards of the axle, this means that the amount of anti-squat can only DECREASE as the suspension compresses (same as the BCD), and given the variation in sag settings between riders, this means that your claim of no movement under pedalling physically cannot be true, because no two sag settings will produce identical anti-squat characteristics. This is not to say that it will not pedal WELL, only that like all other bikes, it is technically imperfect (to what extent, I'm not going to make claims). [/QUOTE]

Couldn't have said it much better myself.
Yes theres a little chain lockout in the initial travel of the Lahars, the axle pivot line is inside the radius of a 24t chring and the rear sprocket is a 18t so its sod all. It does allow the pivot to be 2" lower than it needs to be for neutral inertia effects in my experience. This allows riders to get straight on a Lahar and immediately feel better and go faster. There is big hit advantage to higher pivots and they can be ridden v fast.
Another performance hypothesis in my precise layout is that in the top part of travel, as the riders enduring G-force it is helpful to soften the pedal as the mainframe rises a little with the bump. impact felt thru the foot is reduced. On rebound some of the spring energy acts via the inertia of the drivetrain and leg to drive the wheel forward and the frame down into the hollow. Net effect a smoothing of pedal resistance and ground contact that no doubt contributes to the legendary rep they have for putting down power over big rough.
The bike has a surprizingly wide anti squat envelope- usually riders have to biomechanically compensate for much more eg/ just the varying thrust/chainforce ratio in different gears with rear transmissions. you are correct, best results are with the right springing.





[/QUOTE]What do you mean by neutral drive squat? Do you mean no chain-induced extension or compression force on the suspension, or do you mean no NET extension or compression force exerted on the suspension? And without sounding like too much of a dick... with that floating brake setup, there will actually still be some amount of brake-induced compression. Not that that is necessarily a bad thing, by the looks of it, it would be a relatively small amount and if anything probably only serve to help stabilise the bike and prevent the rear end rising too much as the weight shifts forwards under brakes. I don't know whether this is your intention, but if it is, it wasn't your STATED intention so that's why I brought it up :clue: [/QUOTE]

I guess I mean NET
Actually I run a touch of brake induced jack. The major force is when the wheel locks (transferring rotational inertia to swingarm compression on non-floating systems). Utilising a touch of this kick to drive the wheel into the ground results in an instant ABS effect.
the braking tendancy is to sink equally at both ends. Even slamming something real big in a real bad way doesn't rotate the mainframe forward /buck the bike. This is because any impulse that acts along the swingarm line is tugging above the bike COG providing a backward torque on the mainframe. Thats what sold Nathan Rankin on them in 2003. He tried hard but " nothing I can do will make this bike buck." Actually the size of rearward impulses along the swingarm is at least 10 times higher on conventional bikes and this like going for a quick sprint with your ankles tied to a tree as the horizontal swingarm makes the bike unwind under inertia.

[/QUOTE]Please take care to notice that I'm NOT trying to bag you or your bikes here (I would actually love to take one for a run or two) - only disputing your technical claims (not that yours are worse than the standard bike industry fare). If you can show any of my arguments to be wrong, then I will step down, however I do not believe that you will. I can provide free-body diagrams for any of my own theories/claims that you wish to dispute, if you would like me to.[/QUOTE]

Happy to discuss ongoing. Its refreshing to meet someone with a brain not washed by the ongoing tripe of the industry,


[/QUOTE]On a less nerdy note: they do look freaking cool. What's the price in Aussie dollars? And could you please give us the chainstay length (static and sagged), wheelbase (for each size, if applicable), bottom bracket height (static and with 35% or your recommended amount of sag - it looks pretty high to me), and what is the leverage ratio for the shock on there? Looks pretty high as BCD said, but I haven't bothered chucking the numbers in (ahh also complicated by the fact that there isn't a pivot for the chainstays/tension bars, which makes calculations a bit more difficult). [/QUOTE]

Leverage ratio starts about 4.2- we're running soft initial travel and stabilises at ~2.5 for the 2nd half.

The geometry is basically Nathan Rankin specified after his nationals win on the m8.

Chainstay is 445mm 17.75inch

Wheelbase 1192mm 46.9 inch
BB height 370mm 14.6inch (zero sag sitting on hard ground)
Top tube 560mm 22 inches as measured horizontally centre of steerer at stem to centre of seatpost.
The forward set and layed back seatpost gives a wide range of cockpit size as it moves rearward as it goes up.

Head angle is 63-64degr depending on 8"/ 7.5"/ 7" setting of Fox40 fork.

Frameweight is 5.1 lb + fox dhx5.0 = 6.5lb.

Complete bikes w F40 and full dh rubber is 41pounds
 

LaharDesign

Monkey
Jun 16, 2006
159
0
bcd said:
about the gearbox positions.

I see it like this. for one they are not in the center of the mass.
Your body sits on your BB, that is where inputs go for bike moving
actions. That is where the weight should be centered as close as
possible.

On pivot heights I try and match the height of the rear pivots arc
to what ever the head angle is. that simple. So the wheelbase stays
as close to possible to the same length.

EDIT:

one more thing i might say on carbon strenght. Like was said you can crash and
scrap into a few layers and still have MILLIONS to back it. the bikes i make; as are
the lahars i would think; are overbuild just for that. now bars and seatposts have the MIN amount of carbon to save weight. the diff in a carbon dh bar VS a XC is just wall thickness, but that is not enough to make something strong.
DIAMETER is what makes carbon shine. strenght faxtor goes way up when when the
diameter goes big. snowball effect.
on the mass- height thing. All the weighty mechanicals and frame structure are below the sweep of the crank arm on the lahar. I don't believe anyone else has produced as compact and low grouping of all the mechs and mass as this.

Oversizing isn't always best with carbon. Big tubes can leave you with a fragile product and a heavy one as you wind up using 2/3 of your fibre in panel stiffness and shear loads rather than longitudinal loads.
Also creating some deflection potential for energy absorbsion is important. A lot of designers from metals backgrounds get obsessed with the low density of cf and see it as oversizing potential. Actually carbon is stiffer size for size than cromo so simular sizing is appropriate- you still get ~5 times the stiffness of cromo as same tube size and weight( and over 10x strength, energy absorbsion becomes huge due to thick sections and large yields before failure.
Solid sections like the DHVs I beam Chstay or the leafs on F1GP car swingarms or same size/shape Lahar shock stays work very well, utilising ~90% of fiber for main loads.
 

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LaharDesign

Monkey
Jun 16, 2006
159
0
this diagram illustrates the physics of high versus low pivots when impacting a 4 inch bump. I've chosen this sized bump as its the point when half of the bump force is functioning as a tripping moment at this magnitude with a vertical wheelpath.
The situation with HP bikes is even better than this would indicate.
The HP deal with this bump over 2-3 x the elapsed time of th LP. this means 1/2-1/3 average velocity, 1/4 -1/9 wheel acceleration and force required to move the wheel. - before you even factor in low unsprung weight!
As the bump gets larger from this point, required wheel acceleration on the low piv tends towards infinity and available component of bump force to actuate the suspension tends towards zero.
 

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360

Monkey
Apr 17, 2003
227
1
Edinburgh
I presume this rohloff malarky is still gripshift only?

thats about the only thing that puts me off, having with ridden/tried to keep up with nathan rankin if he cant break it then its good enough for me.