[PHeller]

There has been some debate about how accurate one can be using BikeChecke/LinkageV3 without actually having the bike in front of you.

A popular blog I known for doing anti-squat and leverage ration calculations based off geometry numbers and pictures that I assume allow the user to measure distances relative to known lengths.

Since very few people actually analyze suspension traits outside of the bikes they are building or working on in the industry, this blog is one of the few places where you can compare and contrast different suspension designs.

It's not perfect, and I don't think the author really touts it as such.Just because something doesn't have good anti-squat on a graph doesn't mean it won't ride awesome. But in most cases it helps understand why a bike performs the way it does.

Thoughts on "armchair engineers" and accuracy of BikeChecker's Linkage V3 program?

 

[shirk]

I think the Sexy Enduro bike thread on PB should be pictures and pictures only

 

[PHeller]

I sometimes forget that MTBR is more "lets debate about anything" and PinkBike is "moar pictarz les werds"

 

[raschaa]

From an engineers standpoint it is probably fairly accurate, actually a lot of professional frame designers use Lnkage. On the other hand it is most likely the same as with FEM-analysis, simulation via software is just a heads-up for whoever is interested and can evaluate the data, it is not a replacement for real world testing.

For us "armchair-engineers" it's actually quite useful to compare frame designs and kinematics. If you've riden various bikes and know how they feel, then Linkage is an excellent tool in predicting how bike XYZ is going to behave in comparison to something you are acquainted with. I use it often to predict how shocks will perform in certain kinematic situations and how to fine tune their setup...

my2

 

[PHeller]

Raschaa, thanks for the input.

I've gotten a lot of pushback from folks who simply don't believe that a program can evaluate how a bike will ride, but they forget that the manufacturers use similar programs to design these bikes.

I'm quite interested in how we can use the bikechecker program and associated graphs to determine the ideal shock setup. Maybe you could elaborate?

 

[raschaa]

I'm by no means an afficionado with this stuff, but I'll try to show what I use it for...

I mess around a lot with shock/fork setups and different manufacturers. I try to do reviews/write-ups in german mtb-news.de forum (more or less the german speakers version of mtbr-forum + a little PB added ) whenever I can and have enough ride time on a specific product.

For example, I've done a fairly thorough review of the X-Fusion Vector HLR coil and air shocks and get a lot of queries like, "will the shock work on my XYZ frame?" Since I have no ride time on XYZ I will compare that bikes curves to ones that I am familiar with...

Recently I was asked how the Vector HLR air would fair on a Trek Session:



At first glance you would think the kinematics of these 2 bikes are light years apart when comparing just the leverage ratio.

BUT.....



The forces graphs show that they are actually quite similar. That both will have pretty much the same values for pure force was to be expected, both being 210mm (+/-) travel DH-bikes. The interesting bit is the gradient curve showing force needed per mm travel. The Ion starts off "plusher" than the Session, but at standard sag-level they are getting pretty close to each other and then continue similarly with some offset in the amplitude...

In this case I told the Session owner that by my assesment he could probably throw my shock on his bike and if we were both the same weight he would need only minor changes ( i.e. a bit more compression damping) resulting in a good base setup to move on from...

Obviously I need experience with a certain bike model from which I judge my assumptions.

 

[slow]

Link to blog? Sounds interesting.

 

[moefosho]

I use Linkage Design

No, it doesn't tell you how a bike will ride, it just tells you how the suspension/linkage will work.

 

[PHeller]

Obviously I need experience with a certain bike model from which I judge my assumptions.

I'm trying to do this with Switchback Unveil9/Hammerhead Thumper and the new Lapierre Zesty Trail (29) as well the Unveil7 and Lapierre Spicey. All seem have similar graphs.

 

[raschaa]

Just saw the Switchback frames for the first time... had to google them
Seeing that they're more or less standard FSR spinoffs they will most likely perform very similar to any Spesh or LP frame. The asian manufacturers do like to "copy" existing linkage designs, which is ok, saves a lot on R&D...

Seeing that the Switchback frames are not in the Linkage database you would have to sketch them up yourself I did that once, took me quite a while....

Good thing that the Specialized FSR patent finally expired. That patent was only for N.America, in Europe there are loads of Horst-Lnk bikes. Did you know that the original Horst-Link design was done by Karl-Heinz (Kalle) Nicolai back in the day while he was doing a year at AMP Research during his mech engineering studies.

 

[PHeller]

Raschaa,

The Switchback/Caribou frames were actually designed by Stephan Stark (STS Bike Desgn), who formerly worked for Alutech and is one of the designers of the ICB. Here's MTB-New.de interview with him (and some early version of what would become the Ibex 29 and Ibex 650b).

The same frame with minimal changes (different tubing profiles) is being used by Cove.

It seems like many of Tiawanese companies are "internships" for new designers to try out different suspension styles.

 

[raschaa]

Interesting, thanx!
Now at least we know whose brainpower is behind those designs

 

[laksboy]

thread bump. Anyone else have good info on the ease of use for bikechecker software? Are there any good discussion elsewhere?

I'd like to use it to design some custom rockers for a Ventana EcDM (tandem). Ventana used to make a longer travel version called the Testigo but discontinued it in 2005... They're super hard to find and Ventana won't build a modern version and no longer offers a "long travel" rocker option on the ECdM.

Why you ask? Because shredding gnar trail with my 10 year old on my old used ECdM is the most fun you can have. And we're at the limits of the current travel range and it's no longer upgradeable with a straight steer tube and 26" wheels. The new ECdM gets me 27.5+, boost, and a tapered headtube. All it needs is more travel in the rear so I can run a 180/160 singlecrown on it. And I have 2 toddlers who also love the back of a tandem. So I can justify the expense/effort of such a boutique bike.

 

[Darth Lefty]

Hey, Ventana has a new website! That's cool. Their old one was way the hell out of date.

It seems pretty likely you can learn what you need to know by looking at their other bikes.

How are you fitting a 10yo kid on a full suspension tandem? 14" is the smallest, it's not like a Periscope, and nowhere to put a kidback. Seems like seatpost would have to be totally slammed and shorter crankset.

 

[laksboy]

We started him at age 8 and I have loaned it to friends with 5-6 year olds. Seat slammed and multi-position crank shorteners. A little after age 9 we were able to get rid of the crank shortners. He's now riding with about 1.5" of seat height, but still can't quite clear the seat tube. My next build will hopefully have 160 or 165mm cranks (if I can find) because kids don't need to be pedaling 175mm circles and will help keep me from pedaling his feet into rocks.