leveloneengineering

@Civicowner: Thanks for the reply - it's true that you didn't specifically limit the discussion to reach at the point that we were discussing multiple chainstay lengths - I carried on from the conversation before. Do you think that the difference in chainstay length on your friend's bike also makes his frame slightly more compliant? And if it's more compliant, could that help it track better when loaded in corners or on off cambers? That might be a part of the difference too (not to discount that you prefer the feel of the longer chainstays). The MLink bikes were actually developed and tuned with DAQ. That's essential in making sure that it does in fact work for all riders. Maybe surprisingly, CoG moves forward almost exactly the difference in reach between sizes (for a 75th percentile averaged rider for each size bracket), which means that by changing front center rather than front center and rear center, you're actually keeping the bike balanced. Of course everyone is different with different proportions and not a 75th percentile sized rider for each size bracket, but you've got to start somewhere... Hopefully you'll get a chance to try out the Rakan LT sometime - if you do, let me know what you think!

@Civicowner: Why do you think the weight bias is only dependent on the reach changing? There’s a lot more involved than just that, and I’d argue that it’s unlikely you were comparing apples to apples as much as you think you were with your friend’s bike. Different chainstay lengths for each size is always interesting, but if you do that, you’re changing (among other things) shock rate and travel. So then, what you really have to do is change the entire layout (and shock spec and tune) for each size to make the bike feel the same between sizes...but then you get to the real issue. How do you know that the bike feels the same for different sized riders when you make those changes? And then how manufacturable is that bike? How do you afford the tooling to make all those parts? Is it worth it? Does it actually ride better for anyone? Is it more affordable? More environmentally responsible?

@clindblomenduro: From my personal experience, if you shorten the reach, you also have to slacken the ST angle to make the climbing position (TT length) work. If you shorten the reach, slacken the ST angle, and lengthen the CS, everything works, but it doesn’t descend as well or climb as well on steep trails. Having a steeper ST angle and longer reach is preferable to me for climbing and descending, and the CS length keeps everything in check for tighter trails. It’s only unbalanced if it doesn’t work.

@theshortestcharles: I don’t really look at anti-squat in development or analysis because it’s dependent on geometry, rider size, and gearing. But generally, you’ve got the idea: MLink allows greater change in rate of variables when compared to long link 4-bar systems, much like short link 4-bar systems, while the linear rising rate that these MLink bikes utilize is pretty hard to get from short link 4-bar systems. It’s pretty challenging to get the combination of high levels of change in one variable with a linear constant change in another.

@Rokcore: For sure! Glad you’re interested...A few recommendations off the top of my head would be Tony Foale’s ‘Motorcycle Handling and Chassis Design’ (it’s a lot simpler for motorcycles, but the foundation is there), and Robert Norton’s ‘Kinematics and Design of Machinery’. He wrote my favorite engineering texts. Beyond that, there’s a lot of reducing what you feel riding a bike into quantifiable (and optimizable) math. That sometimes takes a lot of...work.

@gripitandpucker: Those are all issues that as both an engineer and cyclist would bother me as well. Not that it’s any help for your situation, but I probably spend more time working on manufacturing processes to improve quality than I do in developing kinematic layouts. I hope that my efforts (and the efforts of Fuji and their manufacturing partners) pay off and are noticeable on these MLink bikes. We worked hard to make sure that they are not only great riding and performing bikes, but also a pleasure to assemble, maintain, and own over the long term.

But how can it be off-putting if it's vanilla? Everyone loves vanilla! Just kidding. I get what you're saying, but if it was designed your way, I'm sure someone would say 'why not make the rear triangle and the lower link look more similar?'. You can't make everyone happy (which is why there are different flavors of ice cream!) The reason it's designed this way is because it's the most efficient structure possible. The lower link is a weldment of three forgings (no tubes). Pretty complicated forging for the forward yoke section too. One piece! It also has it's own unique performance characteristics that are different from what you can do with a short, parallel rotating linkage. I think there are some cool advantages outside of the kinematics (tire clearance is one of them).

How long do you want? Where do you ride? What's the limitation that you find with 490mm reach and 435mm chainstays in conjunction with the rest of the geometry?

While I appreciate you having Fuji's back on Levy's calling the suspension weird, I do hate to point out that literally zero other companies use anything like it. So...thanks? (If it helps, zoom in on the middle of the chainstay. There's a pivot there, and there's also a tube connecting the seatstay to the chainstay on the non-driveside of the bike). Also, did you know that Vanilla is the most popular flavor of ice cream? Crazy, huh.

@Eiriksmal: No problem. Glad to engage now and then. I actually don't work for Fuji, but I'm the owner of the MLink patents and the designer of these frames. I guess it would more accurately be stated that I work with Fuji. You could always pick up a Rakan LT instead of an S-Works and cut out of work to go ride some more ;)