Behind the Numbers: Unno Dash
Behind the Numbers is made possible by Creaform Portable 3D Measurement Technologies.
Our third bike in the trail category marks the halfway point and another change in suspension layout (and brand) to something a little less common.
Unno, by their description, offers limited-edition, hand-crafted frames. The limited-edition tag being very true, with only 50 of each frame made available every year. Technically speaking, almost all carbon frames are hand-made, but if you have followed the story of Unno then you know this is a little different. It appears that blood, sweat, and tears went into taking Unno from an idea to an incredibly boutique brand that has done everything themselves. Literally everything. They are open about their quest to not take the “easy” road to make a bike by using the far east, choosing to do almost everything themselves instead, including design, engineering, manufacturing, and testing.
A tip of the cap should be given to any individual or team that takes the perilous plunge to start their own company in the bike industry. No matter the level of products that eventually emerge, or not in some cases, it takes guts to do that. Unno has five bikes on offer, ranging from XC hardtails all the way up to full-on downhill bikes. The Dash sits in the middle of their offerings in terms of intent, and it aims to offer the best incarnation of a trail bike from their point of view.
Scanning
Again, a big thank you is extended to Thibaut and Bastien from The Factory bike shop in Fribourg, Switzerland, for letting us borrow one of their most prized possessions. Thankfully, 3D scanning requires minimal contact with the subject; once we had the bike setup it was a completely noninvasive process to scan the bike, drastically reducing the risk of damage to it. One of the more difficult areas to scan on a bike are the fork and shock. Often, a high gloss black can be a difficult surface for the lasers and cameras to get a hold of the data.
The Unno's high gloss black finish is one of the trickier surfaces to scan, but the MetraSCAN 3D can see it well and can switch from a wide laser grid to a single line to help pick up the detail where needed.
For the Unno Dash, the whole frame is a high gloss black finish. And while it is a damn nice, some scanners could see it as a problem. However, the MetraSCAN 3D we used on the Dash lapped up the shiny black surface without issue. It’s a versatile scanning system and allowed the same level of detail to be grabbed as the other, often more brightly colored, bikes. The MetraSCAN also offered the ability to switch from a large grid of lasers to a single line to capture data in hard to reach areas, like deep pockets, and to help focus in on the details you want to capture.
And with the intricacy of the Unno design, and the short link layout and shared pivots, it's very compact in areas. The MetraSCAN was able to really get in there and extract the necessary data, though.
Using VXelemts, the reference points from the scan be picked out and turned into simpler geometry for then generating the kinematic.
The Unno Dash uses a four-bar suspension system with two short co-rotating links. Like other four-bar systems, the instant center is a virtual point in space, depicted here by the engineering standard for showing an instant center - a cat.
The Unno Dash is a 29” wheeled, 130mm-travel trail bike with a 140mm travel fork.
Behind the scenes of Unno and Cero, Cesar Rojo’s other company, there is a hive of minds that have worked on motorcycle projects. There’s the potential that Unno frames include the learnings from this experience in the motorcycle industry, especially when it comes to engineered flex.
Behind the scenes of Unno and Cero, Cesar Rojo’s other company, there is a hive of minds that have worked on motorcycle projects. There’s the potential that Unno frames include the learnings from this experience in the motorcycle industry, especially when it comes to engineered flex.
Unno Analysis Details
Travel Rear: 128.7mm
Travel Front: 140mm
Wheel Size: 29"
Frame Size: Medium
CoG Height: 1,100mm
Chainring Size: 32T
Cassette Cog Sizes: 50T, 24T and 10T
Travel Rear: 128.7mm
Travel Front: 140mm
Wheel Size: 29"
Frame Size: Medium
CoG Height: 1,100mm
Chainring Size: 32T
Cassette Cog Sizes: 50T, 24T and 10T
Continuing from last week, we still have a four-bar suspension system, but now with much shorter links connecting the rear triangle to the rest of the frame. Generally, as those links reduce in size, we see more movement in the curve shapes. The single pivot and long-link four-bar systems we’ve already analyzed having straighter lines, whereas the short link bikes have more pronounced curves to them.
As the link lengths shorten, the angles that they rotate through increase. And with the instant center being depicted by the intersection of those links, it can move around in a bigger window in space. For example, the upper link on the Dash moves through an angle of 58.5° whereas on the Commencal Meta TR 29 the upper link moves only 36.4°.
The Dash’s links rotate in the same way – co-rotating. This is opposite to brands link Santa Cruz and Intense that employ counter-rotating links. A small shock extender bridges the gap from the rear triangle to the shock while going around the seat tube, and it shares a pivot with the upper link.
Currently, only one size of Dash is available, with it being somewhat equivalent to many other brands' medium sizing. Unno is also very transparent with their suspension curves and geometry. Their suspension graphs show the full curves with values on the axes and specific values for their setup range between 30% and 40% shock sag.
Their geometry chart is one step ahead of a lot of manufacturers and shows seat angles for four different seat heights; as your seat gets further up, it angles back to the bottom bracket and gets slacker. Unno also uses an extremely short head tube, at just 85mm. If you prefer a more hands-down cross-country race setup, then this would be easy to achieve on the Dash. But if you run a tower of stem spacers to get your hands higher, then the 455mm static reach of the Dash will start to become a lot shorter.
Mike Levy reviewed the Unno Dash last year and commented on the bike being an efficient climber yet one perhaps suiting a more precise and skilled rider that likes to move their bike around on the trail. He also commented that the Dash did have a bit more feel of hitting the bumps compared to other trail bikes. So, we can take a look at how the numbers and curves reflect those ride impressions.
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The instant centre moves around in space as the links that define it move with the rear wheel. The yellow dots represent the pivots of the bike and the red the IC.
Leverage Ratio
The Dash has 25.36% progression from the start of travel to its lowest leverage ratio at 63% shock stroke, or 64.5% (83mm) rear-wheel travel. After that inflexion point, it’s 10.5% regression until the end of travel. Regression being a leverage ratio curve that starts low and finishes high.
The Dash starts at 2.81 and then falls to 2.1 before rising back up to 2.32. Over the whole leverage ratio curve, there’s an average ratio of 2.26. This is considerably lower than the previous bikes we have seen in the trail category. Remember, lower leverage ratios see the force input at the rear wheel multiplied less when it gets to the shock. But as the ratio gets closer to 1:1 the rear wheel and shock would be moving the same distance. So, a lower leverage ratio system would be moving the shock shaft faster than a highly leveraged system.
But that end-stroke rise in leverage ratios would see the shock shaft then starting to slow down. And the inverse would be true when the bike was in rebound from bottom-out, with the shock speeding up as it reaches the lowest leverage ratio and then slowing down as it went back to zero travel. Sometimes these inflexions can be seen at the beginning of a leverage ratio curve, where the hump and its altering of the shock shaft speed can give a slightly harsh feeling. But as the Unno’s hump is at the very end of travel, the amount of time spent in this region is less than if it were at the beginning of travel.
The shape of the leverage ratio curve is parabolic, and when differentiating it we can see that it is pretty much exactly an x^2 curve.
Unno says that the Dash was designed with an air shock in mind, so this could explain that end-stroke regression, with the general shape of an air shock spring curve having a pronounced ramp at the end of travel. Unno does publish a rear axle load curve and shows the extent of running maximum or minimum spacers inside the shock. Unfortunately, there’s no mention of which air shock this is for, as each air shock has a different air spring curve and with options for OEM tuning for bike manufacturers.
At 35% shock stroke sag, which is what Unno recommends, there will be 38% rear-wheel travel. Still a little less deviation than an extremely progressive bike but a touch more than the Norco and Commencal that we looked at earlier.
The Dash actually runs a 200 x 57mm (imperial length) shock. Currently, this isn’t the biggest of problems with lots of manufacturers still making shocks in this length. Fox recently announced its new DHX2 and Float X2 with continued development in their imperial lengths.
With such lower leverage ratios than the Norco and Commencal, less air pressure would be needed to achieve the same sag and with the shock moving faster compared to a higher leveraged bike, the shock would then be able to generate more damping force. Mike commented that the Dash did transmit more feeling of hitting bumps than other trail bikes, and this could be down to those low leverage ratios combined with a shock that is already quite well damped. Perhaps the combination of the two brings the amount of feedback to the rider up a little, especially compared to something like the Norco with much higher ratios and a less damped shock. This could have been something that Unno designed-in to give the rider enough feedback to know what’s going on down at the wheels. As Mike said, this heavily damped feeling is liked by some riders and not by others.
One thing that this leverage ratio and shock combination does give is support, and as Mike commented, it makes the bike react very well to rider inputs for getting up and over obstacles on the trail. Less of the rider’s input would be taken up in the suspension and more going into finding those sniper takeoffs and landings that the Unno apparently loves.
Anti-Squat
The Unno Dash comes in two build options. The Race version gets a Shimano XTR drivetrain and a 34-tooth chainring, while the Elite model comes with a SRAM Eagle drivetrain and a 32-tooth chainring. We'll stick with the same 32-tooth chainring and 50T, 24, and 10T cassette gears for the analysis, although we can add in how the bigger 34T chainring would affect the bike on the Shimano build. That short link curve style is apparent in the anti-squat, with the extent of the change in the curves becoming more pronounced the harder into the gears you go.
In the easiest climbing gear, the Dash starts at 131% and drops 70% at the end of travel. There is a small lull before the end of the travel where it drops to 66% but it is really contained to the last third of travel. At 35% shock sag there is 83.5%. Compared to the Norco and Commencal, this is a touch lower around the bike’s sag point and would combat a little less of the bike’s load transfer from acceleration.
In the 24T cog, we see a bigger spread in percentages and a more pronounced dip in that final third of travel. Despite there being a higher starting percentage, at 35% sag there is a drop in anti-squat percentage, down to 77.6%.
In the 10T cog, we see the starting percentage way up at 228% and finishing at 47% with the most pronounced belly in the curve. At 35% sag, it sits at 66.8%. In the harder gears, the acceleration magnitude would generally be less than in the lighter gears, and so the follow-on effects of the load transfer-induced squat might be less notable.
Despite there being slightly less anti-squat on the Dash compared to the Commencal and Norco, the much lower leverage ratios would also come into play by providing some support when pedaling. Levy commented that the Dash is an efficient climber, and while we’re not up around or above 100% for the anti-squat, there is still a huge portion of the load transfer from acceleration combatted. And those lower leverage ratios would add support against the forces acting to compress the shock while pedaling.
For the Shimano equipped bike, with its 34-tooth chainring and 51-tooth biggest cassette cog, there is a drop in the amount of anti-squat. The curve shape follows the 32/50 we’ve already analyzed but is just shifted down by 3-4%. With the bigger 34-tooth chainring, and in the familiar 24 and 10-tooth cassette gears, the trend is the same and just sees a shift down of the anti-squat curve of 7.5% and 18% respectively.
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The red IC dot is carried over and creates the blue IC - rear axle line. Intersecting that with the chain line we get the instant centre of anti-squat, the green dot. The orange dot represents the 100% anti-squat mark.
Pedal Kickback
The absolute maximum of pedal kickback comes with the smaller 32T chainring and 50T cassette, with 25°. There is a theme with the Dash to start off with a touch more pedal kickback than the Commencal up until halfway through travel, after which the pedal kickback reduces and finishes following a similar gradient as the Norco, if that were to finish at 130mm travel.
Comparing the Unno to the Commencal, which also has 130mm travel, the Dash has about 2° less pedal kickback in each gear. Taking our example of going off a 1m drop that uses 75% of travel and being in the 24T cassette cog, how fast would the Unno have to be traveling to never encounter the effects of pedal kickback? 8.7kph or 5.4mph. Slower than both the Commencal and Norco by a few kph. If we then dropped down to the hardest 10-tooth gear, where the pedal kickback is considerably less, then that critical speed drops right down to 8.3kph or 5.2mph.
To give some more real-world context, recent rides I’ve been doing around Champéry have shown average descending speeds between 20 to 26kph. If we take into account that for these very downhill-focussed trails, we would be further down in the cassette gears and closer to the lowest 5.2kph critical speed, we would easily never be encountering the effects of pedal kickback for that situation.
Looking at the Shimano specced Dash Race, with the 34-tooth chainring and 51-tooth biggest rear cog, the maximum pedal kickback drops when compared to the SRAM bike, following that trend in the drop of anti-squat. For the 34/51 we see a drop of 2°, for the 34/24 a drop of 1.7° and for the 34/10 a drop of 1.2°. Along with that drop in pedal kickback, we would also see a drop in the minimum speed needed to completely avoid pedal kickback, dropping to 7.9kph or 4.9mph.
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Remember that pedal kickback is calculated with a fixed rear wheel and only looks at the influence on the crank. When we ride it can be a different matter. The blue line represents the bike at zero travel and the green shows how the cranks rotate backwards as the bike goes through its travel.
Anti-Rise
When we look at the anti-rise curve for the Dash, we can spot that short link curve shape again, but much less pronounced. In fact, the Dash has some of the least roller coaster-like curves for a such a short link bike that we’ve analyzed. The anti-rise starts at 80%, drops to a minimum of 66% at 66mm rear travel, and then back up to 74% at the end of travel. At 35% shock sag the anti-rise sits at 67%.
Overall, the Dash would be counteracting two-thirds to three-quarters of the load transfer from rear braking, depending on where you were in the travel. The remainder would then show itself in some suspension rise. This wouldn’t be as much rise as the Norco, but a bit more than the Commencal.
While we see more variation between bikes in the anti-squat, there is a much smaller window for the anti-rise curves. At our halfway point in the Behind the Numbers series, we have the Unno sitting right between the Norco and Commencal. Nowadays, more and more bikes follow this trend of being between 100% and 30% for the anti-rise, with few bikes going wildly outside that range, and the vast majority sitting under the 100% mark.
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It's only the red IC dot we need to calculate anti-rise. The orange one again represents the 100% anti-rise mark.
Axle Path
The Dash sees the most rearward axle path so far, bearing in mind we’re looking at non-high pivot bikes. It starts off with 2.2mm rearward travel at 23% shock stroke, moving then 13.2mm forwards until the end of travel.
At 30% and 40% sag marks, the axle path would still be in its forward-moving phase for when it would encounter a bump. Despite that increase in rearward axle movement, the Dash finishes in just about the same axle position as the Commencal.
Assumptions in Analysis
All of the trail bikes that Behind the Numbers have looked at have been size mediums, and so we adjust our center of gravity (CoG) height to 1,100mm above the ground.
It’s good to remember that the analyses for anti-squat and anti-rise always assume a static CoG. In the real world, this is rarely the case, but needs to be done for analysis’ sake to allow it to be easily calculated and then compared to other designs and bikes. Once we have our analysis it’s then easy to add back in the real-world elements that are relevant to each of us and where we ride our bikes. For more chin-scratching about that, check out the Enginerding article on anti-squat.
There’s no industry standard for the fork in anti-squat and anti-rise analysis. We can either fix the fork travel to generate a single curve or we can adjust the fork travel as we go through the rear travel to create a window. For these analyses, we leave the fork at fixed at full travel. Again, as long as these assumptions about anti-squat and anti-rise are known and understood, it’s easier to analyze and compare bikes.
Final Thoughts
 | The Unno Dash was said to be a fun bike when we reviewed it back in 2019, with a supportive feel on the climbs and it being reactive to rider inputs when wanting to move the bike around and find roots and rocks to jump off. Something that can be seen from its low leverage ratios and not lacking anti-squat. But it could also be that these low leverage ratios, in combination with a well-damped shock, transmit a little more of the bumps to the rider than some people would prefer. This is likely the reason why the Dash is said to be more suited to a precise and skilled rider, one looking for takeoffs and landings in technical terrain rather than just smashing through the lot. But it sounds like the Dash is exactly that. And with it coming from the brand of an ex-World Cup racer and Masters World Champion, it’s not a surprise to see the beautifully crafted Dash be a precise and fast trail bike that demands to be piloted rather than simply plowed down a trail. |
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It seems to only be newbies to the sport and Germans who actually care about these numbers though. Personally I can hop on any bike, regardless of age and spec and ride it down the same trail and over the same jumps and drops without any adjustment... so I'm not a strong believer that these numbers actually matter a whole lot...
Wise words, although it could’ve been put across less offensively.
There is way too much focus on numbers rather than skills out on the trails. Just look back at what people rode in the past, they learnt with practice not talent compensaters.
Dan's new 'Endinerding' series will also help explain some of the concepts - he started with an in-depth look at anti-squat: www.pinkbike.com/news/tags/enginerding
Basically if it isnt a nice even number it was actually manufactured by SAE measurement, but is being converted for convenience.
I dont get why we acknowledge the 1 1/8 to 1 1/4 headtube though.
There's a direct correlation with strava users as well, where an i-phone will get you 6 seconds faster on a downhill than a an android phone, so not a reliable metric in any way.
Meanwhile the guys on old second hand bikes who don't stand around talking are constantly improving and becoming better riders, through effort and skill
I totally get what you mean man.
Made my Day +
Rambling now but people these days say don't drift the rear cause it makes brake bumps.....but it is like the funnest thing and I love it so I will do it. Learn to ride brake bumps and stop whining. I'll rake them out once a season.
If they only knew sometimes I lock up BOTH wheels going into a corner, go full drift then release right when you get a little support and.boost the f outta there. They'd lose their shit hahaha. Double the brake bumps I guess lol
You can have the biggest data set, doesn't mean anything in the real world. All i care about is that it rides good, and looks beautiful... Ticks the second box, who knows about the first.
Still fun to know, if your getting down to the nitty gritty, of bike comparisons.
I think i'll get off pb now, and go jump on me "ancient" franken build ht, and go shread me trails.
For 'metric' shocks (with the RS Super Deluxe family representing those - other manufacturers offer same models in all dimensions) a whole new ETE vs. stroke sizing was devised with longer ETEs for the same stroke. Standard ETE lengths are 190, 210, 230 and 250 with the same shocks coming in 165, 185, 205 and 225 mm ETEs in Trunnion mount (subtract 25 mm from the standard shock to get the Trunnion ETE). The strokes are 37,5, 40, 42,5, 45 mm for the 165/190 mm ETE, 47,5, 50, 52,5 and 55 mm for the 185/210 mm ETE shock, 57,5, 60, 62,5 and 65 mm for the 205/230 mm ETE shock and 67,5, 70, 72,5 and 75 mm for the 225/250 mm ETE shock.
So you have a very standardized set of ETEs and stroke lengths while previously a frame designer with a big enough company could special order a different ETE/stroke shock (which is how we got the 200x57 mm shock, which is just horrible packaging wise). For the same stroke you now either go to a 30 mm longer shock or go Trunnion. That means more space for the shock body, for the damping, etc. and more bushing overlap, which was one of the main benefits of the Deluxe over the Monarch family. And with that longer body bearing mounts (using robust and cheap 608 bearings) is also an option.
So 'metric' is just a name that was used to create a different platform, where the dimensions are 'exact' in metric units, while the older shocks of course got the imperial notation since their dimensions were (sort of) 'exact' in imperial units.
So in the end, we just love bikes being built. One way or another
But I 100% agree, I love watching someone build a bike from scratch in a shed over the course of six months. I am also amazed at watching 4 robotic arms build 16 bikes in 1 minute.
Bike are cool.
I'm just curious why you choose steel over Al. Steel is stiffer, stronger, but alot heavier.
As a counter argument, steel bikes are 100% as good as any other material, it's all a matter of rider preference.
As for my frame being made out of steel, I agree it is partly an emotional decision. The mountainbike frames I had been riding in in the fifteen years before I got this one were steel too (Voodoo, DMR and also a Specialized P1 dirtjumper). But back in the days I also worked in a shop where we built steel frames (typically road and trekking) to order. People came from all over the country with their dreams, whishes and stories about what they wanted, what they have done and what they wanted to do. Some older customers came for something more comfortable. Some others came for something super durable and have traveled the Himalaya on our bikes. Titanium frames we had built by Litespeed but steel frames we built ourselves. I thought it was cool. So I decided one day I wanted one of these too. A frame built exactly the way I wanted it. Now I have it and it rides exactly the way I envisioned it. Happy the way it turned out.
As for steel being heavier. It has higher density so where helps to add volume (for tubes loaded under compression, bending or torsion), using lower density material (that is, aluminium for instance) does indeed make for a lighter frame. Members subject to tensile loading won't really benefit from the lower density material. As for the same weight, steel is typically stronger and stiffer when loaded in tension so when looking at a complete frame, both options (aluminum vs steel) save their weight in different places. If you head to the "geek section" of the Cotic website, you can read more about their decisions. Sure I thing when looking for superlight and not too heavily loaded (CX, road, XC etc) the weight savings are considerable (and maybe more sensible considering the effort put into saving weight in other components too). But when weight saving takes a back seat against durability/maintainability and strength, steel becomes more interesting again.
I personally don't feel the weight of the frame is such a big deal. It is situated nice and low/central, sprung (in case of a full suspension design) and easy to control at both ends (feet close to the bb, hands near the head tube). So yeah, it is more a conscious choice for steel than so much a decision against aluminum. I obviously have enough aluminum components on my bike. I'd be surprised to see someone riding a mountainbike without any aluminum (or steel) anywhere on the bike!
Your analyses are very well-made, it's really a great, great job with alot of investment from you. From my background I know what it takes to produce well documented studies based on a reproductible protocole.
You're a smart guy, I understand that PK is a delicate subject and I think that not a lot of brands must be happy with you displaying their bike's PK values.
So I acknowledge your efforts to go the full transparency way and to educate the audience.
So sorry if I crack the whip a bit - I know you will understand why.
First, you did your AS/PK calculations with a 32t ring. Maybe that ring comes with the bike, maybe you did it for comparisons sakes with other bikes.
But obviously, most of brands sells their 29ers with a 30t ring (e.g. spesh stump ST, trek fuel, Knolly Fugitive, etc...), so it will make more sense to show AS/PK figures corresonding to this ring size, even if a smaller ring size will INCREASE AS/PK figures you display.
Second, you know very well that a bigger ring will DECREASE AS/PK figures, and instead of showing "real world" 30t ring AS/PK figures that will concern 99% of riders, you present AS/PK figures with a 34t ring, that are SIGNIFCANTLY LOWER realtively to 30t ring AS/PK values but which concern very few of us...
Third, the Unno's program is cleraly oriented toward trail/up and down riding, not bike park. In these conditions we are mainly shifting in the middle cassette range and it's not often that we reach 30km/h in the 24t cog, so PK will be a concern on most of cassette range. Moreover, the high AS values will specially be an issue on short burst climbs where a lot of traction is needed (i.e. suspension not figed by AS). And it is difficult on short downhill sections to put the 10t cog because you will have to upshift 7 to 8 times at the next climb.
And I will not talk about freewheel engagement...
So your study is fine, your figures are right, but I found your intrepretation a bit biased toward minimizing AS/PK effects.
Originally I was analysing with a 30T chain ring, as it was what I also ran, albeit on a 10-42 cassette. But as I checked the specs of each trail bike we're analysing I saw that all the bikes are coming specced with a 32T with the larger Eagle and Shimano cassettes.
I can appreciate it's a tough one, as a lot of people will be running different setups. Hopefully the extra bit in this Unno analysis helps to show how a bigger/smaller chain ring change the AS/PK. Your comment also explains it very well.
Just to be clear, there was no bias towards minimizing AS/PK from my side. The numbers are the numbers, no massaging them to make one brand look better or worse!
Behind the scenes I'm working on how we can display pedal kickback/gear ratio/bike speed in a way that's easy to understand, and people can then see how it changes across the entire gear range and speed range. It would be a dream to have something very interactive allowing the reader to input their setup and have it output the graphs for them. But that's a long way off I'm afraid.
For the Norco in the 32/24 gear, and a 1m huck to flat, the minimum speed to avoid PK would be approximately 13km/h (not 34km/h as in the article), for this Unno it would be slightly higher due to the steeper initial PK-curve, approximately 17km/h.(as opposed to 31lkm/h stated in this article) This is assuming a 1.3deg/cm kickback-rate in the first part of travel, taken from the graphs in this article.
This is all very-much a worst case situation, assuming instant hub engagement and no slack at all in the chain at at the start of impact (that's where PK would be highest, as shaft-speed will be highest and the PK-curve is steepest) Also, this is assuming compression speed ('shaft speed') is equal to impact speed, which will definitely not be the case, it will be lower because it takes some time for the rider (the main mass) to build downward force on the bike after the wheels touch the ground.
So in reality you can probably go significantly slower than that and still not experience kickback in the 1m-drop scenario.
As you say, this is the absolute worst case. If you assume constant deceleration as the suspension compresses the total kickback will be greatly reduced, even if traveling at speeds slower than the above. I made graph to try show this effect, i think it's correct. imgur.com/a/COczYag
The only instant that really matters is when you have peak 'shaft speed' (fastest suspension compression). The highest possible compression speed will be your falling speed at the point you hit the ground. After that it can only be lower. So at touchdown is when pedal-kickback is potentially highest, and if you are going fast enough not to have kickback at that moment, you won't have it anywhere in the stroke.
Check out these explanation from Steve (Vorsprung)
m.pinkbike.com/news/video-does-your-suspension-really-work-better-without-a-chain.html
What I didn’t get with theory explaining that PK is not an issue relatively to speed is that even verry skilled pilots like Loic Bruni are annoyed by it, at a point they wouldn’t run freewheel with too much engagement point in order to minimize it. When you check their speeds and cassette range, you definetely are out of range for PK being sensitive...
So yeah, if at my humble level I feel that PK is an issue too, I think that the above theory of speed- related PK sensation miss something...
-First of all, it always assumes the rear-wheel is not slipping, so it's matching the bike-speed. But if the wheel is spinning slower than the equivalent bike-speed (imagine a full on skid with a locked rear-wheel), then there is a higher chance of experiencing PK. In other words, all the analysis here is about the 'coasting' scenario without braking, which in reality may not always hold. I could see Bruni ripping through a boulder-field with the rear brake on, his wheels frequently leaving the ground and the rear wheel coming to a stop in mid-air, before touching down. In that scenario, I think it's feasible to have some kickback on impact. You should hear it though!
-Because: keep in mind that whenever you would feel PK, at that moment you should also hear your rear-hub engaging! In highly dynamic situations, that usually gives a fairly loud 'clang' noise, so there's a good chance you would notice that. Try doing a drop and holding the rear brake firmly closed on landing, or just doing an all-out skid into a turn, if you hear the rear-hub engaging, that is because of chaingrowth and at that point you could be experiencing pedal kickback.
This also means; if you don't hear your hub engaging, you cannot really be having pedal kickback!
-So what other effects may be confused for PK? Chain growth, both upper and lower, requires the pulley-cage to rotate, having to overcome the clutch friction. That is like an extra spring+friction on your rear suspension. I remember an old video of Wyn Masters when he was still racing for Bulls, where they stated they were not using a clutch derailler to avoid this extra friction. It doesn't cause any force on the cranks though, just generally less plush suspension.
-The chain is typically bouncing around a lot because it's not tight between the chain-ring and rear-cog when you're descending. This can give chainslap noise, and also perhaps small sensations of the chain pulling on the chainring. Hard to quantify though... Also, will this be more or less depending on what gear you are in? I don't know really... Doesn't explain that some pros say they are annoyed by PK, and less so in higher gears. A better candidate for that ovrservation in my opinion is the skidding-on-impact.
"Requires a precise and skilled rider" is a nice way of saying that it's going to beat you up and you need to be highly active in selecting good lines.
Hard to believe that a Dune with all that travel would be harsh but it's true. I believe that it's the forward axle path combined with the suspension kinematics that result in the harsh feeling.
It hurts me to see money being wasted so badly.
That said, I'm not in the market for some time so it's a sort of 'Love the one you're with...' ya know?
However I'm much faster and more confident on the Foxy than I was on either my SB5.5 or my Bronson.
When will bike companies learn? Long seat tubes is soooo 2015.
Waaaahhhh. Cry me a river with your tall people problems. It's a lot easier for tall people to find a long dropper for a frame with a short seat tube.
And f****** impossible for a shorter person to ride a bike with a seat tube too long. End of story.
What we're seeing here is more of a solid rear triangle connected to the front triangle by two links rotating in the same direction. That differs from companies like santacruz which had some patents on a solid rear triangle connected by links rotating in opposite directions. (And of course other companies with various patents)
Am I wrong about this? What is a 4-bar suspension?
4 bar suspension called that because of cars, used on solid rear axle cars. Bikes just use a variety of link lengths(this bike using short links, vs something like the Schwinn Straight 8 that has long links), and the links are usually stuck together, since they are so close and there aren't 2 wheels 5 feet apart that the suspension is controlling. An FSR design is essentially the same thing, just with a long lower link and a short upper link. MTB suspension patents have always confused me as they are all just riffs on the same thing, that are all established suspension designs. Clearly there are strange forces in the MTB world that cars don't have to deal with(changing chainline in different gears) and dealing with these forces are where the suspension designer needs to earn their keep. Or just make it a single pivot, or single pivot with a linkage driven shock and call it a day, since it is within 99.5% of the performance of any other system.
www.singletracks.com/mtb-gear/basic-mountain-bike-suspension-designs-explained
ffden-2.phys.uaf.edu/211_fall2010.web.dir/Michael_Stanfill/FourBar.html
www.bikeradar.com/features/the-ultimate-guide-to-mountain-bike-rear-suspension-systems
www.pinkbike.com/news/ask-pinkbike-anything-09-30-2014.html
www.bikeroar.com/tips/a-beginners-guide-to-mountain-bike-suspension-design
I think the 1st link defines it most accurately though that everything but a single pivot,(they called linkage driven single pivot it's own category for some reason though) falls under the 4 bar category.
A Radon Slide, is a FSR bike, is a linkage driven MacPherson Strut, is a 4 bar.
An Unno Dash, is a short link 4 bar.
A DW link, is a short link 4 bar, that was patented with reference to very specific kinematics.
In real life, i'd only ever seen or heard it refer to horst link / FSR / faux-bar designs. This is the first time i've seen 4-bar used to refer to solid rear triangle bikes. But there's a first time for everything. I learned something today.
It is usefull to think of the different kinds of 4-bar bikes as different categories, as they do tend to have generally different riding characteristics. They are all 4-bar however.
My understanding has always been that 4 bar suspension has a virtual pivot point. So FSR, bikes like Eminent, Fuji M link and shortlink bikes all fall in that category. I think of the chainstays of an FSR bike as a really long lower link.
Linkage driven single pivots(some of which people call faux-bar) do not actually fall into the same category, some are just easier to tell they are different. Like an Evil vs a split pivot bike vs a Kona are all linkage driven single pivots, but the Kona and split pivots would be called faux-bar.
Obviously just because they are all 4 bar, that doesn't mean they all ride the same, or even have similar characteristics. It is just a category of suspension, the kinematics are changed by every detail of the design.
Can't really agree there. People have done pretty well on bikes like the Devinci Wilson, Trek Session, Kona, Commencal Supreme, Saracen Myst.
You better let Amaury Pierron, Myriam Nicole, Dakotah Norton and Danny Hart know that they are on way lower performing bikes than their competition.
Single pivots can remain plenty active under pedaling, and everyone always talks about braking, but it is such a tiny difference. I have spent a ton of time on Kona's, and Norco's and can't say the performance is wildly different due to the rear pivot moving from one inch down the chainstay, to one inch up the seatstay. Rode quite a lot on DeVinci's and they felt great as well.
Have spent quite a bit of time on Santa Cruz's, but a bit finicky to set up in my opinion. They are fast and fun, but I have always felt a little disconnected while riding them. Intense Bikes of a few years ago did really weird stuff on the brakes, but once you got used to it, you could actually use it to your advantage. There are bigger differences due to many other design choices and shock set up, rather than the general category of suspension.
If there was an actual large difference in performance then you wouldn't have the most recent DH WC round winner and the WC overall winner last year on them. You like short link 4-bar, I think that those are fine, but prefer bikes with longer links. I really would like to try a modern dialed in version of the Lawwill design.
The other factor is shocks and shock tunes, and a bad shock tune can make a single pivot shine compared to a multilink bike. Can we also talk about how bad monotube shocks suck?
So was that a pure XC bike with LDSP that relies on the seatstay flex vs a shortlink bike. Yep I bet there is a big difference for tons of reasons.
Single pivots work and work great, as is proven by them consistently winning at the highest levels of the sport. If there was an actual large difference(or even probably a pretty small difference) single pivots would not exist. It is not like it is beyond a decent suspension designers ability to design a multi-link bike.
Sure, we can talk about how bad monotube shocks suck too. We better let most of the motorsport world and the trophy truck folks know that their suspension is not up to task first though.
Also, the Oiz is a world championships winning bike that riders are running down courses that include tech features that you probably couldn't ride on a DH bike despite it only having 100mm of travel. I wouldn't bad mouth it's design.
Yes, I have ridden twin tube dampers, they are nice, I have also designed and driven racing car suspension around twin tube shocks, the dampers worked well. I have also ridden bikes and raced cars with monotube dampers they also worked well and performed great. This is another situation where many of the top performances in the sport of mountain biking are achieved using technology that you are claiming is just straight up inferior. If the world champ rides a monotube damper I think that it's performance is just fine and likely not much, or perhaps not any, lower than the competitors on twin tube dampers. I do enjoy the ability to just spin a dial to adjust all modes of the suspension on the trail that most twin tube designs allow. I also don't mind rebuilding and re-configuring the shim stacks to change the damping, when necessary. I haven't needed to do very many times in 20 years of riding FS bikes and 28 years of riding with suspension forks, even though I am pretty picky. With early forks I would need to change stuff out of the box right away, like change the valving a bit and run different oil than what the damper came with, but stuff has gotten a lot better and more tune-able, so I only do that if I feel like playing around now.
In some auto racing classes you are not allowed to have adjustable dampers(Dirt track racing mostly), so the suspension guy in the pits is constantly tearing down shocks and revalving them all day and night as the conditions change. That doesn't mean that the damper isn't good, it just means that it is different and cheaper and lighter.
There are advantages and disadvantages of all three types of dampers, but all 3 types can work very well.
Pretty funny calling out someone as a fanboy, when there is only one of us that is claiming that there is only one correct solution for suspension layout and damper design.
Single pivots and LDSPs are less tune-able than a multi-pivot design, that's just basic physics. I'm not the one going on about how a less tuneable design gives you the same performance as a multilink design, which they dont. You can have plenty of fun on a single pivot and win races, but at the end of the day the design is going to have shortcomings somewhere due to the drawbacks of only having one pivot.
I have definitely had to tear down and re-valve a twin tube damper to get it to perform well. Before the re-valve the best performance was low-speed compression and rebound all the way closed. I have also experienced more maintenance required on twin tube dampers. There are more bad monotube dampers in the bike world than bad twin tube dampers, because a twintube damper is more expensive to produce, so the entry level stuff is all monotube. There also great monotube dampers available in the bike world.
You can't tune any suspension layout without making new parts, so I don't really understand the point made there. There are disadvantages and advantages with multi-pivots and single pivots.
you can see the difference in multi pivot vs single pivot suspension kinematics in that by the numbers. Single pivot bikes cant be tuned like a multi pivot bike can, thats 100% the point.
There is one single pivot bike in that test and it is a not a linkage driven single pivot, and they very purposefully built that bike to have as linear of curves as possible. Which some people like, would feel more confident on and therefore be able to perform at a higher level when using.
If you are talking about leverage ratios not being able to be tuned then you are wrong, you can adjust them without even using a link. If you add a link you have infinite leverage ratio tuning options. If you are talking anti rise or anti squat, those are going to be more linear or more of a gradual curve naturally.
Sure you can't do everything with axle path with a single pivot that you can with a short link bike. That doesn't make it bad, it just sounds like that isn't for you. Many LDSP aren't even really different by much from a FSR bike, since all the pivots are nearly in the same place. Having spent several decades on FSR and LDSP bikes(mostly with the pivot right above the rear axle) and perhaps only 45 rides or so on short link bikes, I prefer the former. I am about to build up a short link bike as my only bike and perhaps I will see the light, and realize that the World Champ is at a disadvantage due to his LDSP and Monotube front and rear dampers.
Did you know I won't be running a stock tune in my bike?
Don't know what your point is at all, so have fun.
Either way, don't get too caught up categorizing bikes like this, four-bar vs. single pivot doesn't tell you much about the riding characteristics of a bike, which makes this series much more interesting
Also, read some tests of EXT (and BOS) shocks and find out if people who's ridden them think they suck..
There is more to it than just having knob to turn. Twin tube dampers flow more oil than monotube dampers, and have higher oil volumes.
My point was more than a crappy damper or a good damper can have a bigger effect than having a good suspension design...
And bigger oil volume is good thing, but could you further explain in what part of the damper oil flow is bigger? And in what way does it make the design superior?
I should add that right now I am running a Fox Float DPS on my bike, my old bike had a CC DB inline, which has about 50% the oil volume of a monarch or float DPS. I dunno what the oil volume difference is for a monotube vs twin tube shock on a piggy back shock, but just due to how the oil flows there has to be a higher volume.
Also, it’s nice to see the acknowledgment of how much more advanced motorcycles are compared to bicycles. Especially when you realize that some of these bikes have most of the price tag of a 600 or 1000cc bike with 1/1,000 the development hours. Which is also why bike brands can dump new models so quickly.
Why would you have the leverage ramp up at the end of the stroke. ? I want bottom out resistance. I can understand a progressive curve maybe regressive at the beginning of the stroke for support . BTW what are the leverage ratios?
Which shock requires more damping force, the one moving quickly, the "low" 1:1 leverage ratio bike, or the one moving slowly, the "high" 4:1 lev ratio bike.
Someone who’s so wealthy they obviously can’t ride.
They certainly can’t set it up themselves.
And they couldn’t ride it properly if it was set up the way it should be.
Like that person who comes into the shop angry that they’re not using half their travel cuz they’re hitting it with their purse.
And don’t understand that if the bikes set up so they use all the travel it’ll ride like a water soaked mattress and they’ll catch their pedals on everything going around corners with their inside foot down.
Or some shredder will blow all his money on it thinking the bike actually matters and they won’t be able to afford to maintain it because it’ll be more temperamental than a billionaires daughter and it’ll just get ridden till the wheels practically fall off while dudes busy reading up on his suspension curves thinking they actually matter.
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Shiftless persons find their chief happiness in complaining.
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-Latin Proverb
Fixed for historical accuracy.