|
| Author |
Message |
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
 |
 Posted Sun Nov 8, 2009 10:55 pm |
| supersonic wrote: | Yep, antisquat and low pedal feedback, works great.
DW to an extent (VPP moves). I assume the Marin is similar. |
Nahm the marin's (Whyte's) quad link has way more pedal feedback than the I-drive. I-drive is unique in it's partial isolation of the drivetrain.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
New
Old
Hardtail
|
|
|
joshtp/mbukman
Joined: 15 May 2008
Posts: 871
Location: the place you drive 4 hours to, WALES! Swansea
|
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
Posted Mon Nov 9, 2009 12:27 pm |
It also pedals really bad, Josh.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
New
Old
Hardtail
|
|
|
joshtp/mbukman
Joined: 15 May 2008
Posts: 871
Location: the place you drive 4 hours to, WALES! Swansea
|
Posted Mon Nov 9, 2009 12:31 pm |
| yeehaamcgee wrote: | | It also pedals really bad, Josh. |
oh yeah, but it shows that it is possible to have a zero chain growth full sus, some clever lincages could help
"oh dear, i seem to have hit a tree."
GT Aggressor XCR 09 + shiny bits |
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
Posted Mon Nov 9, 2009 12:34 pm |
But a zero chain growth full suss WILL have bad pedalling characteristics, whether it's achieved by linkages, or pivoting round the BB shell.
In order for it to have zero chain growth/shrinkage, the EFFECTIVE pivot has to be at the BB shell, see. Keeping the rear wheel at the same distance from the BB shell requires it to orbit it.
Unless of course it's an URT design, which is a whole different kettle of crazy.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
New
Old
Hardtail
|
|
|
joshtp/mbukman
Joined: 15 May 2008
Posts: 871
Location: the place you drive 4 hours to, WALES! Swansea
|
Posted Mon Nov 9, 2009 12:41 pm |
| yeehaamcgee wrote: | But a zero chain growth full suss WILL have bad pedalling characteristics, whether it's achieved by linkages, or pivoting round the BB shell.
In order for it to have zero chain growth/shrinkage, the EFFECTIVE pivot has to be at the BB shell, see. Keeping the rear wheel at the same distance from the BB shell requires it to orbit it.
Unless of course it's an URT design, which is a whole different kettle of crazy. |
hmmmm, well, i supose you are right. however, i feel that by linking in a "dog bone" that prevents movement of the swingarm when toque is applied to the chain, you could improve the pedalling caractaristics.
"oh dear, i seem to have hit a tree."
GT Aggressor XCR 09 + shiny bits |
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
Posted Mon Nov 9, 2009 1:02 pm |
a dog bone won't do anything. If the wheel stays a constant distance from the BB shell, then it will stay a constant distance from the BB shell. Nothing, no matter how complex is going to change that.
Whether it's a real or virtual pivot, the effect of having the swingarm axis inline with your BB is that every crank revolution tries to pull the wheel over the top of the pivot (since the chain/belt's line of tension is above the axis of roation).
It's not so much of a problem with motorcycles, because the high RPM of the engine and drive sprocket means the power is developed much more smoothly, and constantly.
It doesn;t matter how well you pedal, on flats, or SPDs, you will always have a low frequency ONE, TWO, action to your pedalling, which causes the bob issue.
Lifting the swingarm pivot above the chainline, and having a rearwards axle path counteracts the bobbing by making your pedal stroke pull the wheel down, towards the ground, and lifting the rear of the bike up. If done well, this will perfectly match the weight transfer onto the pedals, so the two movements (your weight bearing down on the bike & the rear wheel pushing against the ground, trying to lift the bike) will cancel out.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
New
Old
Hardtail
|
|
|
Northwind
Joined: 06 Sep 2008
Posts: 4511
Location: Edinburgh
|
Posted Mon Nov 9, 2009 2:13 pm |
I was thinking about this in similiar terms to the Idrive, just drop the I  Dependant Drive  Float the BB on its own seperate linkage, with a long dogbone to the rear stay to drive it. Complicated obviously and could do interesting things to pedalling action... Let's see, mount the BB shell vertically to diminish the effect of pedalling (you'd have the BB move fore and aft to keep the "chain" equally distant, which would give a vertical component in its arc but not as drastic as the alternatives) it might ride like it was drunk, however Big landings would suddenly pull the BB backwards.
Ah, but you could make it even MORE complicated- forget about independantly mounting the BB, instead, have a secondary drive, with 2 belts, and have the interface of the belts on your Dependant Drive linkage. It'd be equidistent to both the BB and the rear axle at all times but frees you up to pivot the swingarm elsewhere. God knows what'd happen when you pedal Probably nothing, since the frame's going to weigh about 10 pounds. But hey, the belt will be light.
Or of course we could fit a belt roller or two... But i don't like that. Too easy 
We still do it because we're forever chasing what we've already found |
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
Posted Mon Nov 9, 2009 3:36 pm |
your secondary drive thing would cause the exact same issue as pivoting around the BB shell. Wherever the pivot/drive belt is located, effectively becomes the new BB shell, and you're back at stage one.
Also, if the drive pulley moves relative to the BB shell, then you STILL have the belt-growth problem
See, complicated pointlessness!
However, if it was "made in britain" you'd probably get a load of trendwhore suckers buying it anyway, and proclaiming it to be the best thing since sliced bread.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
New
Old
Hardtail
|
|
|
supersonicLives Here
Joined: 25 Nov 2005
Posts: 47929
Location: Chapeltown, Sheffield
|
Posted Mon Nov 9, 2009 3:41 pm |
Pedal kickback (chain growth) and anti squat are traded off in most sus designs. The less of one, the more of the other, and vice versa.
Zaskar LE 1996
Zaskar Carbon Team
MYSPACE |
|
|
joshtp/mbukman
Joined: 15 May 2008
Posts: 871
Location: the place you drive 4 hours to, WALES! Swansea
|
Posted Mon Nov 9, 2009 5:25 pm |
OK, hers the plan, have 2! yes 2! main pivots, one bb centric, one above the top ring. have a roller on the chain, so that when the chain is under torque it effectively locks out the main bb pivot, and due to the lack of chain growth on the belt, this would mean that only the top pivot was wroking, and, seen as it is restricted by the belt it doesnt move either, however is providesa rearwar axel path for the wheel when you take a big hit.
its hugely complecated, and im sure yee-whatsitsname will now pull it apart, but, hey....
"oh dear, i seem to have hit a tree."
GT Aggressor XCR 09 + shiny bits |
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
Posted Mon Nov 9, 2009 5:31 pm |
well, basically, it wouldn't work. It would just wobble about feebly, and drop the belt.
Come on, ideas that work are great, but now you're clutching at straws.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
New
Old
Hardtail
|
|
|
Northwind
Joined: 06 Sep 2008
Posts: 4511
Location: Edinburgh
|
Posted Mon Nov 9, 2009 5:33 pm |
| yeehaamcgee wrote: | your secondary drive thing would cause the exact same issue as pivoting around the BB shell. Wherever the pivot/drive belt is located, effectively becomes the new BB shell, and you're back at stage one.
Also, if the drive pulley moves relative to the BB shell, then you STILL have the belt-l: |
I'm not sure that'd be the case, since the big problem with pivoting around the BB shell is that you can't do anything clever with the pivot position... Whereas with the Dependant Drive (TM) that's not an issue.
You don't have a belt growth issue becuse the 2 belts are effectievely "hinged" at the DD axle, so you can have the 2 belts at an unchanging length but the total distance covered by the 2 belts can vary, by varying the angle of intersection. I've seen some sort of mad DH bike with a vaguely similiar sort of secondary drive design in Dirt, though the execution and engineering was totally different of course.
Actually, I'm renaming it, it's the Trigonomatic Drive now No, wait, Trigonomical X Drive. X.
We still do it because we're forever chasing what we've already found |
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
|
|
supersonicLives Here
Joined: 25 Nov 2005
Posts: 47929
Location: Chapeltown, Sheffield
|
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
Posted Mon Nov 9, 2009 6:02 pm |
I was looking for the one Cannondale made using a similar concept, and likewise, didn't actually do what it was supposed to.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
New
Old
Hardtail
|
|
|
supersonicLives Here
Joined: 25 Nov 2005
Posts: 47929
Location: Chapeltown, Sheffield
|
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
Posted Mon Nov 9, 2009 6:17 pm |
still get terrible squatting under power though.
Mae'n enw i wedi ei grafu, hefo hoelan wedi rhydu, ar y lechan las
New
Old
Hardtail
|
|
|
Surf-Matt
Joined: 22 Apr 2008
Posts: 4199
|
|
|
yeehaamcgee
Joined: 07 May 2007
Posts: 6004
Location: Worth Nails
|
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Search
