NAHBS 2015: Funk Cycles’ 20 lb Titanium Full Suspension La Ruta 29er, Plus Colorful Ti Anodizing

too much drooling here!

Remarkably light but also one of the poorest pedaling FS bikes you’ll find, and with the carbon rotors certainly one of the poorest braking. Despite their claims otherwise, this is a weight weenie build. It would be best shredded in a chipper. It’s pretty though.

It’s a shame that NOT ONE Ti manufacturer that builds flex plate designs has figured out that the plate needs to be elevated off the BB. I even tried to get James at Black Sheep to do one custom for me but could never get him to start the project.

I personally think Ti flex plates are great solutions for FS but it doesn’t mean you can ignore suspension kinematics. Custom builders are NOT suspension designers.

M.C. Slammer, I will add my 2 cents even though I am not a BR expert. What Seven says about the layer being more brittle than the regular surface is true but when they say “which will eventually propagate into the tube wall, ultimately causing frame failure” it should say ‘may eventually”. This is a case of something on paper not matching up to what works in the real world. Titanium bolts have been anozized for years and there seems to be no difference in longevity over those and regular titanium bolts. Having worked for a large titanium company I have seen many things that were supposed to be really bad practice with titanium work just fine and not have any failures.

So on paper it could be bad but in the real world it is no problem.

@ ligero- thanks for your insight. I never thought about the Ti bolts.

@ Martin – no, I don’t need to. I once owned a Moot YBB which took a similar approach and had similarly poor (in fact, worse) pedaling dynamics.

This design is a simple mono-pivot with a main pivot location immediately behind the bottom bracket. Such designs have grossly inadequate anti-squat characteristics that lead to massive pedal bob. These bikes count on a combination of limited travel to mask the bob and/or large amounts of pedal platform in the shock to hide it. You get poor suspension action or poor pedaling dynamics (or both). It’s unavoidable.

Suspension designs such as these failed in the market over a decade ago and are only carried on by boutique manufacturers that don’t understand suspension kinematics. There’s a simple fix for it but these guys are builders, not engineers and their customers don’t know better. They’re drawn in by the exotic materials and the minimal weight without realizing that a simple change that would affect neither of those things would produce a better riding bike.

The thickness of the anodized layer is really, really small. See this chart http://web-o-rama.net/titanium/1anodization.html and note the exponent on the vertical axis. So there’s not much brittle TiO2 on the surface to stop the rest of the tube from flexing. E.g. the chart shows 1000 Angstroms for purple which is 0.1 microns which is 0.0001 mm (1 mm being about the thickness of a Ti tube, maybe a little on the thick side)

I’m not sure the discoloration that happens in the HAZ of a weld is a problem in and of itself or if it’s an indicator of issues within the weld.

M.C. Slammer, does not sustain.

20lb FS Ti bike is amazing. Haters gonna hate! :-/ Sorry its not an enduro bike @craigsj

I for one would be willing to ride the living sh!t out of that bike for as long as I could. Purely in the name of science mind you, not because it is one of the nicest looking bikes I may have ever seen. Just sayin’. Willing Science Tester

I would love to read what the lords of the weld at firefly say about the anodizing. If they haven’t already I bet tyler would test a tube out of curiosity.

@craigsj – have you ridden a pair of SiCCC rotors yet? What are you basing the poor braking performance on? I have no experience with them. They’re basically a carbon composite where instead of epoxy binding, it’s a ceramic binder.

I wouldn’t go in on the flex plate thing myself, but I 100% disagree that “frame builder” and “suspension designer” are mutually exclusive titles.

Thanks for the feedback on the bike, particularly the positive, but also the negative because it brings up some interesting points.

First off a minor one… the chain stays on the show bike are only 17.35” / 440mm. I’d consider that to be on the shorter end of the scale. Our standard bike has stays that are 0.4” longer; we were able to shorten them on this bike by moving the flex plate to the top of the BB and bending and offsetting the seat tube.

In terms of Seven’s take on anodizing, as Mike said, if they have evidence to back up their claim, I’d love to see it, but as far as I’m aware it’s without real basis. Sure, Ti oxide is detrimental within a weld (inhibits grain formation), but it’s an issue there because the metal is molten and the oxide can migrate around within the HAZ and lead to a weakened structure. But that doesn’t mean it needs to be kept off a frame for the rest of it’s life, nor in fact can it be: the surface of a Ti frame will oxidize on it’s own over time, albeit a thinner and less visible layer than when anodized. That’s why an old brushed Ti frame tends to take on a slightly bronze-ish hue after many years. Last I knew Seven had a lifetime warranty (as do we), so they’re clearly not worried about THAT oxide layer.

In terms of the pedaling efficiency of the La Ruta, online forums have made me well aware that it’s not a design that makes sense to everyone on paper. All I can do is try to encourage people to try riding one before criticizing too harshly. @craigsj, I have owned a YBB myself for many years, and while I love the bike in many ways, I agree that it has a tendency to bob. My La Ruta is a completely different animal though, and frankly I’ve ridden it back to back with a buddy’s Tallboy and I honestly don’t think I am sacrificing anything at all in terms of plushness or efficiency… in fact I think he might be. I’m no doubt biased, but I’m a new addition to Funk having bought a bike from them as a customer a couple years ago; I’ve worked my way in more and more over the past year because it’s a company and a design that I really believe in.

@craigsj – that’s what I figured you’d say. It’s kind of pointless to
Debate the bike seeing youve never even thrown a leg over it and are
Still going to compare it to a soft tail. But that aside and speaking about to soft tails what about Castellano ? He’s a MIT engineer I believe are you saying his suspension platform sucks too ? Come on Craig you can do better than those blanket statements.

Hey there Bikerumorers… I own a LaRuta. Two of them (one is my wife’s). And yes – we pedal the crap out of them all over CO. Front Range to Fruita. Unlike other soft tails (like Moots YBB), the LaRuta uses a true air shock – of your choice. In my case, a high volume-canned Fox. It took a ride or two to dial in the dampening & rebound, but since then its been set-it and forget-it. Whatever bobbage is there, it’s negated by the shock’s platform setting. Best part: no bearings means no maintenance. Less time in the garage, more time on the trail.

Sure there’s plusher, longer-travel rigs out there. But let’s be honest folks – It’s 80mm of travel (at best). You can’t compare it to a four-bar linkage, DW link or VPP. Apples to pumpkins. As custom soft tails go, it sets the benchmark.

If your definition of enduro riding is 3 hours up for every 1 hour down (you earn your turns baller style), the LaRuta is hard to beat. My 2 cents.

I also like that the builder is responding, refreshing indeed. And @Kovas, thanks for your candor as well.

If that’s the answer (“yes, modern air shocks and short travel makes up for a convenient but simple suspension design”)… okay. Yeah. I find that acceptable. I mean, I find the travel on a Thudbuster useful for its intended purposes, and it has no damping whatsoever.

Dan from Funk, This blue/purple anodizing color is a perfect match with some PROTI Fully Forged Titanium Bolts. Not only the best in the market, but they have a very nice Blue color available. Consider that for your future projects. Congrats on the bike!!! VERY NICE.

The Kettle rotors are certain contentious… I had a pair lying around so I thought I’d throw them on for the show since they’re light and look cool. Certainly it’s an easy swap if they aren’t up to par. I was surprised that there were a number of gravel road bikes at the show with Ashima AiNeon rotors which are also crazily light (Moots, Boo among others).

We don’t build the La Ruta claiming it to have the most advanced suspension design. Our claim is merely that it’s the simplest, the most reliable and easiest to maintain, and yet still extremely effective. I think the bike is a soft-tail done right, and it excels on long cross country rides. It’s not built to be an all-mountain or enduro bike. Despite what one might think about the pivot location (this is actually hard to pin down somewhat because the bike doesn’t flex at a single point, or even in as a simple a way as one might think), it is an extremely efficient pedaling bike with the shock set to pro-pedal. Yes, it does get a little more plush if one opens the shock fully, and yes it does become more likely to bob under hard pedaling. But as I alluded to before, with my La Ruta in pro-pedal, it bobs less than my friend’s Tallboy in the same setting, and I think the rear is just as active. If I’m riding the bike on smooth terrain, I forget I’m riding a full suspension bike because it feels almost like a hardtail, and yet when I hit rougher trails and technical sections, the suspension makes itself felt.

To address Craigsj, Tom, and Madm3chanic’s points about the pivot location, and why we don’t try to raise it… this isn’t a new idea, and in theory it’s obviously a good one. The trouble is that doing so becomes quite difficult without greatly complicating the design and fabrication, and in so doing losing a lot of the great things about the existing bike. The flex plate takes a LOT of stress, and the attachment of it’s leading edge to the frame has to be very strong structurally. That’s why we build it with the thickest walled BB shell that Paragon make, and it has a triple-pass weld to make sure it’s as strongly attached as it can be. It’s just not possible to mount the plate to a thin-walled tube like the seattube or the downtube – it would tear the tube within 100m of riding. To raise the plate would require building up a structure to raise it above the BB shell, and that’s going to add a lot of weight, complication, and frankly visual complexity to a design that is at present elegantly simple. The other issue is that plate needs to be close to parallel to the chainline, otherwise the forces from pedaling will over time cause it to buckle. That presents an issue if the plate is raised up above the bb, but then needs to avoid the chain (angle up or down) as it moves to either side of the tire. Basically, the plate can’t do this, the chainstay tubes would have to. But that wouldn’t leave much room at all for the plate, especially since as it gets higher, the tire is further forwards and eating up space. I’m not sure that any of these issues are entirely insurmountable, but in combination I think it isn’t possible to get around them all and preserve the elegance and simplicity to the design that we value so highly. And frankly, given how well the bike rides in it’s current form, I sincerely question whether it needs it.

One more comment on this subject: not sure whether people noticed, but the flex plate in the show bike is mounted onto the top of the BB shell rather than it’s center, which is the way we (and everyone else) normally mounts it. Admittedly it’s only about 0.875″ higher, but this ought to be a somewhat better pivot location, and yet preserves the visual simplicity. At least that was my thinking.