Paging Derby Yet another linkage bike....
These I think are a Italian firm with a top 5 DH UCCI WC rider. The info re other systems seems to have the same type of reasons for application as the DW link, what do you think?
The Carver looks a nice frame
Thanks in advance
Yes, it appears this MDEBIKES designer has taken the DW design lead and adjusted it slightly.
This I-Link design may appear to be another close copy of the 1st generation dw-Link available on the Iron Horse Hollopoint in 2003. But there is a subtle difference.
The early dw-Link produced a more parabolic or elliptical path. The 2nd generation dw-Link such as the current Ibis and Iron Horse version, are further refined and improved, especially in braking reactivity.
This I-Link produces a round path, like a monopivot swingarm, if a monopivot could be practically put in the same place as the center of axle path this I-Link does.
It shows an effective center of axle path rotation during travel similar to what was found earlier on the better Horst link designs, although this I-Link center of axle rotation is higher than a good Horst link, so it produces a more rearward path. The pedal feedback climbing in the granny gears in bumps would be noticeable to experienced Horst link or dw-Link riders.
The test whether it infringes on pending international patent would be if it produces a anti-squat calculation claimed by the DW patents.
This round path I-Link unlikely produces the no-feedback DW most balanced anti-squat calculation and ride time effect, so it is probably safe from future legal problems.
Unlike Ellsworth and Specialized who claim patented linkage fashion, DW patented specific mechanical effects. The I-Link may look close to a dw-Link but it won’t perform as well. Although the I-Link appears to be a better than average design for smoother climbing and downhill.
This "I-link" suspension could not be sold in the USA without a dw-link license. The '329 dw-link patent claims would prohibit that.
Just curious, are there any other suspension designs available in the US that have a front loaded anti squat response (i.e., more response early in travel than later)? I take it all other designs have a flat response or a back loaded response.
Dave, if I was a frame designer/engineer I'd hate your guts for your design.
Originally Posted by _dw
But since I'm a regular schmo that gets to buy a dw link, ride it, and not worry about axle path circumference squat ratio travel moment of inertia weight transfer, I think your design rules.
I think if you and derby ever met, there might be some sort of engineering space time continuum disruption causing all the brains within a 5 block radius to explode. Yes, even the puppy and kitten brains, so for the love of humanity stay away from each other.
With the notable exception of the “back-loaded” trademarked VPP “s” path design and it’s near copies, all practical use trailing-arm suspensions have a “front-loaded” reduction in ant-squat, monopivot or multi-link.
Originally Posted by frayed cable
What the dw-Link design does is produce a more acute reduction in anti-squat, from a specific near 100% anti-squat balance to much less, below 40%, than more common configurations of monopivot or near round path multi-link trailing-arm chain or belt drive suspension.
Here’s a link to the patent and the graphic of the anti-squat curve claimed:
Dave mentioned above in this thread that the round path of the Italian maker’s “I-Link” bike would produce such a rapid and specific reduction within the patent claims. So an elliptical path is not always a characteristic of a dw-Link.
But most designs have a more limited reduction of anti-squat. Usually with lower monopivots, and similar pedaling FSR/ICT link styling, the anti-squat maximum near the top of travel is far below 100% and the range may reach as low as the dw-Link design to produce smooth pedaling in bumps, but allow much energy wasting bob without firm low speed damping tricks. A few suspension start near 100% such as high monopivots but don’t fall off in anti-squat anywhere near so much as the dw-Link.
Combining compressed spring resistant to rear suspension squat-geometry and there becomes a small range of path geometry that does not produce too little or too much anti-compression. Too little combined anti-compression and the suspension bobs from the acceleration efforts of the rider. Too much and the suspension noticeably stiffens up and resists bump compression when accelerating or climbing.
Interesting in it’s notable exception to reduction in anti-squat during deepening travel is VPP. VPP, unlike a near round radius path has very low anti-squat near top-out, and progressively ramps up more anti-squat geometry as travel compresses, and then plateaus or falls off in anti-squat near bottom of travel. Besides VPP’s noticeable cadence feedback and suspension stiffening while pedaling in larger bumps, when pedaling on smooth surface there is a very noticeable extension then drop-off of the BB height when standing and climbing, particularly in the middle and granny rings. The VPP action is probably the closest to hardtail feedback of any suspension geometry design. Some riders prefer hardtail like pedaling, with relaxed suspension only when coasting. Hardtail action actually reduces momentum and reduces traction when the trail gets rough, by kicking the rider up and down.
With near 100% anti-squat near sag the dw-link converts pedal input into forward acceleration without the added up and down movement that VPP produces when pedaling hard while the trail is smooth. And the dw-Link relaxes anti-squat balance very quickly when compressed by a bump so the shock is free to act without chain tensioned resistance and the rider goes forward without wasted up and down redirection of an over stiffened suspension such as VPP or a high monopivot geometry.
Its important to make the distinction between patents and trademarks too. Adding to what Derby wrote, the dw-link patents cover a wide range of suspensions for all kinds of vehicles. In order to protect those that are especially useful for bicycles or other human powered vehcles. The dw-link trademark really is a quality mark intended to cover the suspensions that are especially suited for and useful for intended purposes. A bicycle suspension covered by the patent but not up to the performance standards of the dw-link quality mark (performance parameters for bicycles) could still carry the patent number but would not be allowed to carry the dw-link logo. A suspension for other vehicles covered by the patent but not up to the performance standards of the dw-link quality mark (performance parameters for whatever vehicle the suspension is being used on) could still carry the patent number but would not be allowed to carry the dw-link logo. This is the case with many suspensions that infringe the dw-link patent(s).