[zedro]

It's not a Lawwill, it's a true parallelogram linkage with the CC at the drive output (note the lack of chain tensioner). It won't need a brake linkage/floater.

it'll still want to brake jack without some linkage in there; the torque put on the axle link will want to extend the suspension (how bad or benign the effect would be i dont know, but thats what the forces will want to do). Traction would still be pretty good though.

and if it is in fact a true parallel linkage, thats pretty much a waste IMO; a concentric cantelever type would deliver the same result with most likely less weight and better stiffness.

 

[CBJ]

Not much info talk about GT's bike now second year runing. Don't know if they made any changes for 2007 besides color and specs.

 

[zedro]

Not much info talk about GT's bike now second year runing. Don't know if they made any changes for 2007 besides color and specs.

that bike is way underated, dont think it's getting it's due (maybe it's the non-DH geo?). I really like the layout, and it looks like they simplified the swingarm?

 

[Bicyclist]

It's the non DH-geo and the big gear ratio jumps.

 

[jvnixon]

Got the rotec stuff posted now. http://www.sicklines.com/interbike2006/rotec

 

[no skid marks]

Cool,now that you can see a full picture,best design yet I recon using the Suntour box. The axle path will be slightly rearward,not to disimiler to the front wheels path,a touch steeper.(Hard for me to tell cause my Mac doesn't like me holding bits of paper and pens up on the screen,and I can't be arsed getting pins and scissors and making a mini replica.
I like it.

 

[gemini2k]

Not much info talk about GT's bike now second year runing. Don't know if they made any changes for 2007 besides color and specs.

shortened and lowered it 'bout a quater inch. Which is just about what i'd like. Mine's a bit too high and long . But still glorious

 

[thaflyinfatman]

it'll still want to brake jack without some linkage in there; the torque put on the axle link will want to extend the suspension (how bad or benign the effect would be i dont know, but thats what the forces will want to do). Traction would still be pretty good though.

and if it is in fact a true parallel linkage, thats pretty much a waste IMO; a concentric cantelever type would deliver the same result with most likely less weight and better stiffness.

Nah it won't, the axle link won't rotate at all relative to the front triangle (same deal as a parallelogram floating brake setup). The only effects on suspension compression/extension will be forwards weight shift due to acceleration, and the axle path (which is slightly rearwards and will want to induce some amount of squat).

I agree, it does seem like a bit of a waste, but who knows what their design priorities were.

 

[zedro]

Nah it won't, the axle link won't rotate at all relative to the front triangle (same deal as a parallelogram floating brake setup).

not true, a floater is more neutral in general because it pivots around the rear axle so is basically uncoupled from the suspension. Do some force calcs on the parallel "Lawill-esque" layout, that torque is still there, albeit much reduced (so the squat you mentioned may level it out).

my floater is setup almost like the divergeant Lawill linkages; the geometry improves traction over braking bumps but that high single pivot provides lotsa squat, add the two and the bike brakes level

 

[blue]

shortened and lowered it 'bout a quater inch. Which is just about what i'd like. Mine's a bit too high and long . But still glorious

How's the Nexus held up?

07 looks like it has a trigger shifter...mas bueno.

Wish I had hookups at Pacific...

 

[SOil]

Some more info on the Versus gearbox frame:
http://www.mtbr.com/videos/versus.mov

 

[thaflyinfatman]

not true, a floater is more neutral in general because it pivots around the rear axle so is basically uncoupled from the suspension. Do some force calcs on the parallel "Lawill-esque" layout, that torque is still there, albeit much reduced (so the squat you mentioned may level it out).

my floater is setup almost like the divergeant Lawill linkages; the geometry improves traction over braking bumps but that high single pivot provides lotsa squat, add the two and the bike brakes level

The torque is still there on the axle link, but the compressive component exerted on the top link/swingarm will be canceled exactly by the extensive component exerted on the lower arm. It's the same principle; a couple moment generated ANYWHERE on the axle link will yield the same reaction. You should know this man, it's first-year statics stuff.

 

[gemini2k]

How's the Nexus held up?

07 looks like it has a trigger shifter...mas bueno.

Wish I had hookups at Pacific...

nexus is great. Shifter a bit sketchy . I think when i get back to the states ill be replacing it with the trigger if i can find it aftermarket. Hookups are glorious

 

[metzy]

Still plugging away with my bike, the gearbox seems to run pretty nicely, just a few more bits and she will be a runner.

 

[no skid marks]

Looking good.

 

[thaflyinfatman]

Gotta hand it to you Kiwis - you come up with some awesome stuff.

 

[ÆX]

looks super.

very close layout to what i am working on.

how high is your pivot for bb?

how high is a lahar?

 

[Sandwich]

unless it's for XC, you may want to make that a bit lower.

 

[jvnixon]

Not sure if anyone broguht it up but the hayes internal gearbox

here:
http://www.dirty-pages.net/nieuws/petespeed.html

translated version:
http://sicklines.com/petespeed_translated.html

 

[xy9ine]

awesome work metzy

 

[EVRAC]

Awesome

 

[no skid marks]

He said earlier it was for XC+ and he's a tall guy,looks great.
The Hayes thing got killed by legalities I think.

 

[jvnixon]

thats too bad. Internals of the RN01

 

[konastab01]

unless it's for XC, you may want to make that a bit lower.

Depends how the bike is set up though and the Lahar has a high pivot and tracks like a mofo on crack.

 

[no skid marks]

I'm guessing sandwich was talking about the toptube etc not the pivot hight.

 

[SlackBoy]

Still plugging away with my bike, the gearbox seems to run pretty nicely, just a few more bits and she will be a runner.

You stole that seatpost off the sky tower didn't you rob

 

[Sandwich]

talking about the top tube/seat tube.

konastab have you ridden the lahar, or are you just hypothesizing?

 

[no skid marks]

I have and it does track well. Do you have a racelink sandwich? Rides similer to that(slightly lower BB and different shock+links),the BMW is probably the closest feeling bike I've riden to compare too.

 

[Sandwich]

I'm sure it does, it's relatively similar to the racelink in design.

I was just curious as to if that dude had ridden one or if we was just playing make believe.

I'd love to own a lahar, they're a little slack and long for me though.

 

[konastab01]

I have rode a MK8 Lahar and am waiting on my 9.
They are one of the best bikes for racing in my opinion.The angles just mean that you need to go fast to make it better

 

[jeremyb]

So for the people who have built their own gearboxes a-la derailleur in a box, I assume you have a freewheel on the bottom bracket spindle? what did you use for it?

 

[ÆX]

generally a bmx freewheel.

but because the freewheel is at the crank you do not
have a gear ratio to multiply the number of of ratchets
as compaired the one revolution of your pedals, so
you have a larger lag where the pedel hits a ratchet.

making for a slow engagement point.

so, try and get the most number of clicks per single rotation
to get a good feel at the crank.

 

[jeremyb]

generally a bmx freewheel.

but because the freewheel is at the crank you do not
have a gear ratio to multiply the number of of ratchets
as compaired the one revolution of your pedals, so
you have a larger lag where the pedel hits a ratchet.

making for a slow engagement point.

so, try and get the most number of clicks per single rotation
to get a good feel at the crank.

Thanks BCD, just need to figure out how to adapt one to a 32 or so tooth chainring and I'm half way there!

 

[ÆX]

i'd just weld some tabs fror a 4 bolt ring on there.

 

[jeremyb]

i'd just weld some tabs fror a 4 bolt ring on there.

 

[EVRAC]

Nice little writeup on the Diamondback gearbox bike

http://www.dirtmag.co.uk/2006/09/exclusive_diamond_back_gearbox.html

 

[LMC]

Hi guys,

this is my 1st post here and i have a question about the following..directed primarily at thatflyinfatman and Aaron from lahar
sorry to go back to this

Hey Aaron, is Dodds' bike using a positive or negative output gearing? Because if it's a negative gearing, he could actually multiply the braking power... and obviously if it's a positive gearing, the reverse is true.

so say i have a onboard rotor, of diameter say 150mm.
i want to increace the power of the rear brake.

As with Metzys rig the input sprocket is fixed to the disc, so to multiply the braking power do i have the larger sprocket at the rear wheel, or one smaller that the input?

i know this has been discussed before but as i read the post quoted above and Aarons reply, they seemed to have contradicted as i read it, unless im missing something.

 

[EVRAC]

With an onboard rotor, if the drive sprocket is bigger than the wheel sprocket then I guess braking power would be reduced by that ratio. It's another reason it's too bad we can't use a small front sprocket like mx bikes.

This thread just cracked 20,000 views!

 

[joelsman]

holy bar height on that diamond back, must be 45 or more.

and soon as prices are reasonable I am getting a gearbox bike!

 

[DHS]

the best part is, Diamondback america, has no idea about that bike