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Dave Weagle’s Split Pivot suspension system awarded patent
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
From the man who brought you DW*Link, here's another one.
The spiel doesn't mention efficiency but does mention fun. Can we assume this is more for 'gravity' bikes then?
It looks a whole lot like Trek's ABP, as mentioned in the article:
From: http://www.bikerumor.com/2010/07/27/dave-weagles...
The system's official site: http://www.split-pivot.com/
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The fact that the rear triangle can be separated opens up the possibility of carbon belt drive on a AM/DH rig.
Wouldn't you want gears on your DH / AM bike?
DW first announced this in 2007 and it was suppose to be available in 2008. Trek launched their ABP system at about the same time 9slightly later)
I wonder if the hold up has been a legal wrangle
"Wouldn't you want gears on your DH / AM bike?"
In the hub.
You could run a very tight tension in the belt, no derailers, no chainslap. No cleaning the cassette.
"no deraillers, no chainslap. No cleaning the cassette"
Increased unsprung weight and rotational mass (not what you want in a sport that all about acceleration) less efficiency and unbalanced rear end...
The only way to do gear boxes is in the frame like the GBoxx or Pinion designs. Still need to work on weight, efficiency and price though
Wouldn't there be some chain growth as the suspension moved through its travel.
I think you'd need a tensioner in there somewhere. Do they make them for belt drives?
It does look like it is more about fun on gravity bikes rather then pedaling efficiency. The wheel path is the same as as single pivot design, so this one is all about controlling the force on the shock.
would need to be concentric with the bottom bracket and the rear axle needs to be on the chainstay (as it is with this design).
Belt tension required to stop skipping or riding up the side of the pulley is too high for a belt tensioner of the style you're contemplating to work. It would otherwise feed back into the suspension action for sure in my view, based on the couple of weeks I spent on the Spot Rocker 29er SS.
As far as I can see the system is designed to work on bikes with conventional rear gears. The hanger is shown as is the splines for the cassette, they've just excluded them from the pictures as they're not part of the frame.
the rear triangle is no longer a triangle
Another suspension design to add to the hundreds...
So out of interest... does anyone know if there is a suspension design that pivots around the BB? This would negate the need for a tensioner would it not?
Is this what the GT I-Drive is all about or have I (in my slightly 'late Friday night state') missed something?
Morgan's Zinn has a pivot concentric on the BB from memory. To suit the Rohlof hub.
Rob, Gt I drive is a single pivot that allows the BB to pivot independently, keeping the same effective chainstay length and bb to seat height without the need to have the pivot at the bb.
There are a few designs that place the pivots at the BB. Has the disadvantage of needing wide BB with big bearing to fit over the BB shell.
Garard from over at 26inches was importing a brand a while ago that used this set up but right now I can't think of the name
Just remember most of this is marketing hype. Most suspension systems in use now whether they are 4bar or some from of virtual pivot have wheel paths that divert 5/5s of freak all from that of a conventional high mounted single pivot anyway.
Edit: Remembered the bike Dean Ti Ace http://www.deanbikes.com/mountain/ace/ace.htm
Ah... talking of Pinion, is this P-1 thing new?
http://www.pinion.eu/en/produkt.html
The Pinion looks good and they appear to have done real-world testing with it.
However it appears to require a custom frame with the bottom bracket replaced with the Pinion gearbox.
Still, it is the best place to locate the gearbox (central, low and not on suspension items). It will be interesting to see if it makes it into production and if it can be made at a weight and price point making it attractive and viable for MTB use.
I'd love to get rid of the chain, gears and dérailleurs - but I like my gears too much and am not prepared to ride single speed...
(Sorry - just realised this is a bit of a thread hijack!)
cheers
Jon
The idea of a gear box at the bb is not new. Bikes first came out with this in the 30s
G-Boxx have a long history too. The weight (And $$)penalty generally meant that they were limited to high end DH rigs but as technology gets the systems lighter and cheaper it's only a matter of time before we see more of them
http://www.g-boxx.org/10-bikes_history.html