I met a company representative at Eurobike this year that couldn't tell me the most basic features of their new bike and had the technical understanding of a walnut. Sad, really, and not the first time I found myself in this kind of situation. Stefan Laile is definitely not one of those people. When he starts talking, your mind has to shift into overdrive just to follow his most basic thoughts on suspension and really, all things bike. And just like that, ideas turn into a real-world bike - the UHP-FR V2.
UHP stands for Ultra High Pivot, FR for Freeride because of the extra travel and V2, because a quick & dirty first concept already exists, but a second attempt at it saw quite a few things changed in the end.
The work on the concept bike started about a year ago and for a month now Stefan has been riding his titanium prototype, trying to get answers in the real world that no other bike out there was able to give him. It's only natural that many of the features are custom-tailored to his size and the way he thinks it should handle.
Stefan does not work in the bike industry professionally but he considers himself a tinkerer who runs a blog as a hobby without profit. He didn't go to university, rather attending a Realschule (a type of intermediate secondary school) and getting a degree as a metal cutting mechanic with an additional education as a technician and a specialty in engineering. With a perfect grade average, the now 32-year-old could have gone on to study more but decided against it due to various reasons at the time.
Today, he works as a Tool & Fixtures Designer at a small business in Friedrichshafen for a living. Having access to a large tool shop with turning lathe, milling machine and testing bench at home helps with his endeavors and he does kinematics construction in Linkage X3, CAD construction with Fusion 360, readouts of air shocks in IOG_calc (his own calculation software) and force-travel measurements of rear shocks.
In his blog insanityofgravity.blogspot.com
- which unfortunately is only written in German (although you can use Google translator to turn it into English and get an idea) - he looks at various bike companies' kinematics, helps to tune shocks, questions design decisions (and offers suggestions) and even takes apart some answers by Pinkbike staff regarding suspension, that we might have to reevaluate.
Most noticeably, his bike uses a really high pivot design, which in itself isn't really new. However, compared to some large-scale manufacturers, who have to abide by derailleur manufacturers' maximum cage movement, he does have other options. For others, only 27 mm maximum of rear center lengthening during travel is possible but his number sits at 77 mm - this feature alone should answer the question of whether this project bike was something that could be turned into a mass-produced bike easily. So, we're looking at a massive rear wheel axle path movement, which has been achieved by placing the main pivot ahead of the bottom bracket and in quite a high spot. The bike's high anti-rise value sits between 170 to 180 percent within the SAG area.
The reason why he chose to go for a giant-size pulley is more out of practicality than anything else. It was easier to just buy a 28-tooth chainring with SRAM direct mount, rather than having to machine an expensive prototype, but the large-size pulley can also distribute loads well. The bike's anti-squat comes to about 190 percent, depending on the gear used. In his opinion, this is the best-calculated compromise to keep the rear end stable when you need to accelerate hard in some trail sections or transfers.
In another study, Stefan wants to test the effects of a floating disc brake system with his design. The mounts already sit on the side of his seat tube and it's just a matter of time when he gets to it.
Travel measures 183 mm vertically at the rear, combined with a 190 mm travel RockShox Zeb out front and the shock length measures 240 x 75 mm. After taking apart, looking at and tuning different manufacturer's shocks, he picked Intend's Hover for his own bike since it allows him to set up the negative chamber the way he thinks it should be done generally, which is a whole other topic of discussion in itself.
An effective seat angle of 80 degrees ended up feeling a tad too steep for him in the end. That's why he pushed back his saddle slightly and feels that 78.5 degrees could be the sweet spot, if ever there should be another concept bike.
Since Stefan is rather tall at 192 cm, he picked a reach of 510 mm. A standout design trait is the extra-long steer tube length (160 mm), ending in a stack height of 688 mm. He wanted to experiment with a higher front and feels more comfortable and secure with this setup. The titanium frame without shock weighs 4.1 kg and the total weight of the bike comes to about 17 kg.
Mounts for testing a floating brake system with the design in the future.
Manufactured in China, the titanium frame in combination with a pragmatically chosen parts spec (including a few lucky sale opportunities) came to a bit over €6,000 in cost. Considering the amount of money you could invest in a bike out there, that's not the worst way to spend your cash on a unique ride.
It'll be interesting to see what we will see from Stefan Laile in the future, or if his one-off is going to remain a one-off. He tells us that his head is full of other ideas that he'd like to turn into reality, suggests that this won't be the last time we'll get to cover some insanityofgravity.
Of course, it gives all that up with the huge angulation on the lower guide. Ah well.
(most direct mount chainrings are clocked by design)
Also, why would the gear selection change the pedal kickback in the this case? The cassette and idler always move together regardless of the gear, and the idler to chainring link always has the same gear ratio.
Antisquat isn't just related to pedal kickback.
Just as you said.
The important bit here is that the chain part only comes into effect if the chainline length changes through the travel because it can only then have an effect through pulling on the suspension.. With a swingarm mounted idler this does not happen, therefore the chainline in the cassette to idler branch doesn't have an effect. But it does in the idler to front chainring branch, as the idler is moving relative to the chainring.
(The relationship of the bottom jockey wheel will change through the gears and the travel, so mech clutch forces will impart different forces depending on the gear chosen, but that's a) not anti-squat, and b) negligible compared to chain force anti-squat)
Just so you know, I wrote the algorithms that Linkage software uses to calculate AS for any configuration with the idler not on the front triangle.
Both chainlines (cassette to idler, idler to chainring) are required in the calculations.
Consider a high single pivot configuration, with the idler mounted concentric with the main pivot. Do you consider the idler as being attached to the swingarm or to the front triangle? (It’s both!) If the idler is considered as being on the front triangle, then you’ll get one value for AS. And by your logic, if the idler is considered as being mounted in the swingarm (infinitely close to the pivot), then you’d get a very different AS value.
Your suggested method fails at this boundary condition.
Lots of people use these graphical methods, but not many truly understand how it is developed.
Here’s some guidance. Consider a single pivot layout with a conventional drivetrain. When you intersect the chainline and the swingarm line, you’re actually locating the instant centre of the wheel wrt the suspended mass.
Knowing that, you can now consider the mechanism of a swingarm mounted idler, and work out how to locate the IC of the wheel wrt suspended mass for that configuration.
You’ll find that both chainlines are involved.
You’ll also find that this method gives the same result as the ‘normal’ method at the boundary condition when the idler is mounted concentric to the pivot.
Hope that helps.
Also, im not talking about a concentric solution, I'm talking about an idler mounted to the swingarm elsewhere than the pivot. Like in the case of the bike we have here.
It relates to the amount of chain that is wrapped/unwrapped from the casette and idler pulley as the suspension moves through its travel.
I realise this bike is a swingarm mounted idler, but the case of a concentric idler is a crucial boundary condition to assist with understanding the difference between the two configurations (idler mounted on front triangle vs idler mounted on swingarm).
With a concentric mounted idler, you can consider that the idler is mounted on the front triangle, therefore the 'conventional' graphical method is applicable (and correct). Despite there being no distancing between the idler and the cassette, this method still uses the chainline from the idler to cassette in the algorithm. If you change the sizes of the idler or cassette (or both) it affects the amount of wrap/unwrap of chain on these items as the suspension moves through its travel. This is reflected in the change in point where the chainline intersects the swingarm line, and therefore affects the anti-squat.
Please don’t dismiss the concentric pivot example as being irrelevant for this case. If you can understand the role of the rear chainline in the case of a concentric pivot idler, then you’ll see that it’s still relevant in THIS example.
Hope that helps.
But not sure super high pivot point is way to go?
Especially in Titanium !
What your probably looking at is where the chainstay and seatstay bolting to essentially thr swing arm. Which then utilizes a pull link to rotate the rocker link.
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