After a bit of a hiatus, we're back.
If you'd like to know more about the Behind the Numbers series, aren't familiar with the terms being used, or want to know why we're doing it then check out our
Introduction article for all the information.
Next up in the series is the Santa Cruz Megatower, and our final bike of the enduro category.
But first, let's explain that hiatus.
Among the plethora of suspension designs out there we can somewhat simplify them into two categories: long link designs and short link designs. Long link designs, such as the Specialized Stumpjumper Evo that we’ve previously looked at, have relatively big distances between the pivot points - take the main pivot to Horst pivot as an example.
Bikes like the Santa Cruz Megatower have much shorter distances between the pivots, meaning their links often rotate through larger angles in a shorter space of time. Given that it’s these links that are defining the instant center position a small change in the pivot points can result in a big difference in the suspension curves, far more so than longer link designs.
It’s then up to the designer to balance the pivot point placement along with all the other inputs and requirements and arrive at their desired characteristics. There’s no more or less priority for short or long linked designs, just that a poorly timed sneeze when placing a pivot would have a drastic effect on the bike's character.
Up until the Megatower we had been analyzing relatively long linked bikes, and so our degree of accuracy when taking the measurements was more than enough for those layouts. But for short linked bikes we needed to find a more accurate way to capture the data to ensure this same level of accuracy with these more sensitive layouts.
3D scanning is a method of data collection of real-world parts and objects. The data can then be used to construct digital 3D models for product development, quality control and analyzing bike suspension.
Creaform is a Canadian company that develops and makes
portable 3D measuring instruments, and it is with Creaform that we have partnered to capture the data for the Behind the Numbers series.
Creaform's HandySCAN 3D in action producing the live mesh of the Megatower. And right, the entire scan of the bike once completed.
Using their
HandySCAN 3D handheld scanner they generated a 3D mesh file of the Megatower that is accurate to 0.025mm. That’s an accuracy as small as a human hair, and a good magnitude finer than the manufacturing tolerances achievable in the bike industry. This 3D mesh file is then imported into CAD software to generate the CAD model.
The scan itself is comprised of millions of small triangular surfaces that build up to create the bigger surfaces of the bike. The scan of the bike is pretty data heavy, and for post-processing a decimated version is used to speed up the proceedings, decimation being the process of reducing the number of triangles while still keeping track of the actual geometry of what you’re scanning. From this decimated model the necessary surfaces and points are grabbed, like the pivot points, axles and tubes of the fork and seat post. And from these extracted points we can get the geometry and kinematic of the bike.
It sounds like a lot of effort to get just a 2D sketch of a bike, but it’s remarkably fast and the accuracy is so damn good that we monitor the tolerances of individual parts of the bike. Even the fork and tires have tolerances that mean in the real world they sometimes don’t follow their designed dimensions. The scan itself took a time of about 15 minutes and the whole process went from set up to final 3D model in under an hour.
So, what does this mean for you? Confidence in the series and the information that you can take away. The same can still be said of our previous bikes, but now we’ve just taken a step forward to ensure accuracy and confidence for all bikes and layouts.
A huge thank you to Creaform 3D scanning experts and mountain bike enthusiasts Simon Côté and Louis-Philippe Turgeon, for their willingness to collaborate and their invaluable help and efforts. Also, a thank you to Santa Cruz for being open and up for discussion and for being one of the catalysts in us hunting for higher accuracy. A long distance thank you to Québec local bike shop Mathieu Performance who lent us a bike for the scan. Last but not least, thank you to Bastien and Thibaut at The Factory Bike Shop in Fribourg, Switzerland, for letting me loose on one of their test bikes with a measuring tape.
Let’s get on with the analysis.
Almost all of the Santa Cruz bikes have now moved over to a lower link driven shock layout. Maybe they now focus more on having a progressive and smoother changing leverage ratio? Maybe they like water bottles? Either way, it's a good move.
The construction needed to achieve this layout is decidedly more complex than some of the more traditional double diamond layouts of the other bikes in the enduro category. Complexity in most cases leads to some extra weight. The complexity needs repeatable quality in manufacturing, and if the form of the frame naturally twists, turns and splits then more material is added to ensure that the expanse of edges and corners won’t provide a strength problem. That being said, at least all of the complexity of the bike is low and centered, and the quality of the Santa Cruz frames and attention to detail is impressive.
Santa Cruz Megatower Analysis Details
Travel Rear: 159.5mm to 163.6mm
Travel Front: 160mm
Wheel Size: 29
Frame Size: L
COM Height: 1150mm
Chainring Size: 30T
Cassette Cog Sizes: 50T, 24T and 10T
Added to all this are the adjustability options. A small chip on the lower link and rear axle allow four different bike setup possibilities. Adjustability is good, as long as it's in a useable range, allowing the rider to nip and tuck the bike to their riding needs and terrain demands. The downside of this adjustability is the added curves on the graphs, but stick with it and you'll start to see the characteristic changes that each adjustment option brings. While the changes to geometry that the shock chip adjustment gain might be small (a measured 0.26˚ on the head angle and 3.58mm in BB height) the differences in suspension characteristics are far more pronounced. The 10mm chainstay adjustment has a bigger effect on the geometry, balance, and weight distribution, while also having a noticeable change on the suspension.
Leverage RatioLong CST / Low Chip – 31.5% progression with an average ratio of 2.85.
Long CST / High Chip – 27.54% progression with an average ratio of 2.82.
Short CST / Low Chip – 30.57% progression with an average ratio of 2.81.
Short CST / High Chip – 26.78% progression with an average ratio of 2.78.
The Megatower has a good chunk of progression in every setting, with around 31% in the low chip position and around 27% in the high setting. The chip adjustment has more of an effect than the chainstay adjustment.
While not at a truly extreme amount of progression it is a little on the higher side of the fence when compared to a lot of other bikes in this category.
What is high are the average leverage ratios. Lots of bikes at the moment, with metric stroke shocks and 160mm travel, are hovering around a 2.76 average ratio. They’re doing this by using 60mm stroke shocks. The Megatower has a 57.5mm stroke shock as standard, and so the ratios take a jump up. Higher ratios are going to transmit more force into the shock, and so need higher spring rates or air pressure to support them. Higher ratios will also be moving the shock shaft at slower speeds, generating less damping force that would need to be accounted for in the shock tune.
Bikes with more progression and high ratios tend to ride dynamically deeper in the travel, which is why Mike Kazimer in his
review probably preferred the high chip setting to not only raise the BB a smidge, but reduce the amount of overall progression and have the bike dynamically higher in its travel when riding.
The further towards the extremes we go the more the setup compromises rear their head. We witnessed this with the very linear Orange Stage 6 and Specialized Stumpjumper EVO.
For the Megatower the extremeness is not as severe, but there will be a swing to either two scenarios. Setting up with a normal amount of sag would then mean spring rates that would perhaps deprive the bike from using the available travel, whereas setting it up to use the available travel would result in increased sag. This lower sag in combination with the progression could lead to riding with more time spent in a harder sprung and lower leveraged portion of the suspension, potentially coming across as harshness.
In these situations, it could be beneficial to side with less sag; this would cause the bike to ride higher in the travel and in a zone of lighter spring rate and higher leverage.
The leverage ratio curves are quite constant in their change. Only right at the end of travel in the low chip position do we have a bit of a shoulder of increased progression. Depending on shock setup this extra shoulder, coupled with an air spring's natural ramp, could provide a small wall of overall progression at the end to hit.
Suggestions of tricky shock setup from Mike perhaps come from these higher leverage ratios in all settings. The high leverage ratios with high progression define the character of the squish and there are going to be less perceivable ride feel changes when fiddling with the adjusters on the shock, due to this high amount of force going into the shock and its slow movement.
The full range of the Megatower anti-squat.
A zoomed-in look at the anti-squat to show more detail for the lighter gears.
Anti-SquatFirst off, apologies for the overload of curves, but 4 bike setups and 3 different gear sizes result in a busy graph.
The first anti-squat graph shows the entirety of the range of figures, which is big. The second graph zooms in to +160% / -100% anti-squat to give a bit more detail for the gears more relevant to climbing.
For the easiest gear (30T chainring and 50T cassette) there’s nearly always above 100% anti-squat, so in that gear the bike should do an OK job of combatting the weight transfer. As the gears get harder the amount of anti-squat increases, but so does the exponential shape of the curve, so much so that in the hardest gear the asymptote drops the anti-squat down to just shy of -360%. Luckily, this trend is towards the higher gears and so perhaps further away from the climbing gears. The increased anti-squat at the beginning of travel in these gears could go some way to stabilizing out of the saddle sprinting.
This trend in rapidly decreasing anti-squat is also going to lead to a drop off in the pedal kickback towards the end of travel. The most extreme drop offs come in the low chip position, so running the bike in high could also smooth out the anti-squat while still keeping that flavor of high weight transfer support to end of travel drop in pedal kickback. It does, of course, depend on the riding scenario, component choice and impact speed as to whether the theoretical pedal kickback will actually be felt.
Coupled with the leverage ratio, which would lead to a somewhat active supple feel, this healthy dose of anti-squat is a positive, and as it seems from Mike’s review the bike does indeed pedal well and have the feel of moving forward with pedal power rather than bogging down into the suspension with lackluster anti-squat there to support you.
Anti-RiseThe familiar VPP style curve resides in the anti-rise graph, too, although at least this time there aren’t 12 curves to try and absorb. The overall range of the anti-rise, however, is much less, going between around 85% and -25%.
The higher figures at the beginning of travel will equate to a degree of squatting to combat weight transfer from braking. As the bike goes further into the travel this effect will diminish, and in the last 20mm the bike will actually extend a touch and slightly accentuate this weight transfer, rather than combat it.
To do this combatting, or accentuating, the suspension system needs to give up something else, and in the case of anti-rise, and the Megatower, it’s perhaps some sensitivity in the suspension at the beginning of travel. Some designers would prefer the opposite and have low transitioning to high figures, giving perhaps more traction in the first portion of travel and increased weight transfer support deeper in the travel, when the riding scenario might be of a higher energy level.
Again, it’s not fully clear if this was intentionally designed in or if it’s a resultant of optimizing other characteristics. But there’s maybe a sneaking suspicion that Santa Cruz focussed on some other suspension factors, like leverage ratio and overall frame layout and packaging, and other characteristics had to follow.
Axle PathYes, the scale on the graph is different, but don’t worry, we’ll do a comparison with all the bikes on the same graph so you have a good overview of the whole enduro segment of bikes. Zooming in does allow us to see the details and nuances of the individual bikes.
What we see is that the Megatower does have around 2mm of rearwards axle path. But in reality, this will only be of use when landing from absolute zero travel. As from the sag point onwards (25% shock stroke equates to about 45mm of rear-wheel travel) there is only a forward trajectory on the rear axle.
While this is commonly thought of as bad, it depends on if you’re looking at the compression stroke or rebound stroke. A high pivot bike will, of course, move its axle out of the way with more ease as the axle path is more in line with vector created by the bump. But on the rebound stroke the axle will be travelling straight into, imagine head on, into the next bump. It then has to decelerate, pass zero velocity and accelerate away again.
So, a benefit in one direction can be a deficit in the opposite. A more forwards axle path will require more energy to move out of the way, but will not be firing itself directly back at the next impact.
Like all the factors involved in a bike, there’s a point of balance in there somewhere. It’s a hard job balancing 100 spinning plates on your own, and Santa Cruz has done a good job of taking their older generation layout and improving a lot of characteristics, not just in the suspension department.
One thing we can see is that the high chip position looks to be the more favorable position with slightly more rearward travel up to the sag point and then around 3mm less forwards travel.
Final Thoughts | The Megatower takes on many of the suspension traits from the Nomad and Bronson, most of these being positive traits that will assist the bike in living up to its intended purpose as a 160mm 29er. The adjustability is a nice touch and is going to provide owners with options to change the character of the bike, although the high position could be the choice setting.
There are some interesting quirks in the suspension characteristics that are simply there as a result of choosing this short counter-rotating layout, but it seems from looking at the characteristics, and our ride impressions, that if you're into grabbing it by the horns it will go bloody fast. |
Previous Behind the Numbers Articles:GT Force Suspension AnalysisOrange Stage Six Suspension AnalysisMarin Mount Vision Suspension AnalysisSpecialized Stumpjumper EVO Suspension AnalysisIntroducing Behind the Numbers - A New Suspension Analysis Series
Check out www.datumcycles.com to see how shock and fork rates impact suspension when combined with kinematics.
Cheers!
Or even more intriguing, V10 27.5 vs V10 29.
It seems as we get deeper and deeper into innovation and development, alot of stigmas are getting debunked.
So, a benefit in one direction can be a deficit in the opposite. A more forwards axle path will require more energy to move out of the way, but will not be firing itself directly back at the next impact."
That is a great way to think about it! I've never heard it articulated quite that way, but it's really slick.
linkagedesign.blogspot.com/2019/12/pivot-firebird-29-2020.html
100% = the suspension does not extend or compress due to rear brake forces being perfectly attenuated
1-99% = the suspension extends slightly due to rear braking forces being partially attenuated
0% = the suspension extends due to rear brake forces that aren't attenuated at all
0% = the suspension extends a lot due to rear braking forces being amplified
some people like > 100% since it can help balance out fork dive
others prefer 100% since it may make the rear feel more active under braking
0% is basically always bad
A rising anti-squat curve can be good for the reasons stated in the article.
A falling anti-squat curve may also be good in my opinion, since you get better traction in rough terrain when the bike is taking repeated hits and sagging deeper into its travel. But you also prevent the bike from pitching forward quite as much on extremely steep rock rolls when the more weight is over the front and the rear end has a tendency to rise up.
less than 0% = brake forces amplified
less than 100% may make the rear more active under braking (I've heard some mixed opinions on this one)
less than 0% is basically always bad
This is counter to my understanding of it and what you nicely outlined.
The percentage value is to do with how much of the load transfer from braking is being counteracted.
0% means none of the load transfer is counteracted and the suspension extends. Like you’ve mentioned.
100% actually means that all the load transfer is counteracted, and to do this the suspension needs to compress to counter the bikes want to pitch forward and extend the suspension.
As you get closer to 0% the bike counteracts less and less of the load transfer. But it’s still compressing, just less and less as you approach 0%. Kind of how you say, but there will be compression of the suspension.
More than 100% and you’ll be putting more than enough countering in to combat the load transfer, and further compress the suspension more than you need.
Below 0% the bike will extend, and accentuate the bikes natural want to pitch forwards and extend the suspension.
Hopefully that helps.
Anti-Rise IMO opinion is a very interesting characteristic because suspension designers largely haven't agreed upon a "good amount" or a "sweet spot" like they have with most other characteristics.
“PARRY: More than 100% anti-rise implies that, under rear braking only, the suspension will compress. Conversely, less than 100% anti-rise implies that, under rear braking only, the suspension will extend.”
“CLOWARD: The higher the anti-rise number the more the rear suspension will compress. 50% anti-rise is pretty low and braking will have a smaller effect on the suspension and the suspension will remain active. At 100% the suspension will compress under braking. At 150% the suspension will compress even more and can cause a lockout feel while braking over bumps.”
This article seems to agree with me: enduro-mtb.com/en/mtb-suspension-kinematics
I suppose it might have to do with the method used to calculate it. But in reality, 100% doesn't really mean much anyway, since different riders will have different centers of gravity on the bike, and it's constantly shifting around.
1. The front suspension will be compressing during braking so some bikes and some riders (Fabian Barel when he was with Kona and set up his floating brake different from stock to compress the rear) prefer the rear to compress so that the bike would squat on both ends to keep the chassis more level with the ground.
2. Deep in the travel the action is from a large hit and is therefore transient and only lasts a short time. The Santa Cruz design becomes much less compressive at high amounts of travel which should allow the bump to pass through easier but as it is a short duration event it shouldn't upset the bike much. This is what I feel when I ride my Megatower.
Yamaha also makes guitars. Doesn't mean you can play guitar on their MX bike.
I think modern mega-negative air shocks are approaching linear rates through most of their travel that the tiny little shoulder in the graph isn't really going to be a big deal. And it's hugely beneficial for a coil, isn't it?
ep1.pinkbike.org/p3pb17749863/p3pb17749863.jpg
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SC V10 2017, on 27.5" wheels according this review is pretty vertical up to 83% of rear travel. Rune V2 is vertical up to 87% and Rune V3 up to 75% of their rear travel. Banshee is pretty unique against the majority of the market.
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In forward path, 1) the rear wheel must accelerate in relation to the mainframe and 2) clear the obstacle with more energy required. After first impact, during the rebound phase, it is still somewhere in its forward path, it is deccelerating (moving back) and when hitting next obstacle, it must overcome the energy already accumulated in the rear shock.
In rearward or vertical path, the wheel slightly deccelerates. After first impact, during the rebound phase it must accelerate slightly (requires lighter rebound damping?) and while hitting the next obstacle, it must too overcome the energy stored in rear shock. But if both axlepaths were working against the same leverage ratio curve, the forward path would have the tougher job. IMO.
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I think the reasoning behind forward axlepaths of modern frames is more complex. It definitely has something to do with desired anti-squat and pedalkickback, because with 1xMega drivetrains, we route the chain in directions that induce higher pedalkickback. And that is direct input to the rider.
No, it falls below 100% almost exactly at the sag point. So on any bump/compression the anti-squat flips from gently trying to extend the suspension to gently trying to compress it, and vice versa for extension/jounce/rebound. Luckily the curve is at it's flattest in the climbing gears, so this flipping of the anti-squat is likely much less noticable compared to older VPP bikes, which are notorious for "inch-worming" up punchy climbs, and the more you pedal squares the worse it gets.
The argument still stands, that crossing through 100% anti-squat flips the effectiveness of the chain forces in supporting the suspension, exaggerating any bob present from not pedaling perfect circles.
It is physics, not just a press release or individual reviewers opinions.
It will help folks figure out what bike is for them (are you OK with running a coil for a bike to ride the way you want, or do you want a less progressive bike with a tunable air shock)?
And Lazer Cats...
"What we see is that the Megatower does have around 2mm of rearwards axle path. But in reality, this will only be of use when landing from absolute zero travel. As from the sag point onwards (25% shock stroke equates to about 45mm of rear-wheel travel) there is only a forward trajectory on the rear axle.
While this is commonly thought of as bad, it depends on if you’re looking at the compression stroke or rebound stroke. A high pivot bike will, of course, move its axle out of the way with more ease as the axle path is more in line with vector created by the bump. But on the rebound stroke the axle will be travelling straight into, imagine head on, into the next bump. It then has to decelerate, pass zero velocity and accelerate away again.
So, a benefit in one direction can be a deficit in the opposite. A more forwards axle path will require more energy to move out of the way, but will not be firing itself directly back at the next impact."
Could this be part of every bike review?
Can we have a "Behind the Numbers" shootout and then compare that to the on-bike field test results?
Can the frames be mounted to a test rig and report on stiffness?
A searchable database?
How about data for components? Example Brakes. Measure the clamping force, friction, and heat dissipation rather than count the number of pistons and hope that equals performance
Thank you, Dan Roberts!
This 3D scanner is cool though.
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What situations? For descending with some pep, I'd rather run more sag. Running more sag moves you into the firmer part of the curve giving more pop and feedback from the trail, while also increasing negative travel so you can charge over holes and drops and maintain traction. And climbing I'd still like more sag, again getting to the firmer part of travel where you can get the trail feedback and have something to push against to move around and maintain traction and front-rear balance.
The only situation I can think of where hanging out in the high leverage area is beneficial is if I had mild hemorrhoids and weak legs wanted the saddle to be super gentle against my bits while still maintaining some speed through rough stuff that I had to stay seated for. Or maybe if I had a leg injury and wanted less trail feedback through the pedals.
Does it make sense?
If you are looking at "wheel/shock" curve, you can have a straight line...
... and then looking at "shock/wheel" curve for the same thing, the straight line is gone. And none of these are really helpful to predict what will happen on the field.
Did they cover the specialized enduro?
But I feel the title graphic would be even more rad if the lazzzer beamzzz would pass through the wheels / spokes...
The Hightower felt slow from the first pedal stroke in the driveway.
Sure it went down better but the slogging pedaling feel and harshness over roots
was a real drag. If you take a close look at the suspension differences you can see that the lower pivot on the Tallboy
is almost vertical and the Hightower its almost horizontal.( like the mega tower)
i'm no suspension designer but I think that a horizontal lower link transfers the forces from a real wheel hit backwards initially and it is felt as deceleration. I would rather have the forces more vertically oriented like on a standard 4 bar.
I think VPP is over. it was useful back when pivot points added slop and noise, but today thats not so much a problem.
It’s good on the descends in my opinion. But after I built up my Antidote dark matter, sadly it didn’t even climb as well as that beast.
I’ve owned a bronson v2 and a nomad v4. I’m just not a huge fan of the pedaling characteristics. That’s just me, cue SC fanboys that get hyper offended.
But I’ll see how the CJ 29 performs.
Sold my bike in the fall and have been demo'ing many bikes since. Had a Megatower for 3 good hard long rides over varying terrain. Overall it was a great, fun bike, and did a lot of things really well. First, it's reputation of being a big stiff bike that needs to be ridden really hard to get anything out of it is exaggerated. I found it actually worked best riding it at 5 to 7-10ths vs 8 to 10-10ths and pushing it hard. Found when you really pushed it, it had some trouble keeping rear end traction during hard steep braking over chunky terrain. Tough situation for any bike, but I was surprised by this from this bike as I assumed this suspension design was one of the best of the best. I guess that's the compromise over other attributes? That's most of my local terrain and found it robbed me of speed. It was one of the fastest bikes I've ridden through more flowly, less chunky terrain though. That was my only negative as it was a fun bike... but I didn't find it any better than a lot of other bikes. I don't think the value is there. It's an expensive bike for no real reason other than the brand. Free bearings for life is a nice touch though.
The other issue I had (more an annoyance), was since the suspension design is so complex and "busy", it's difficult to live with. Setting up sag is annoying, and cleaning the bike properly can only really be done by taking apart the linkages (not a good thing on BC's west coast). The flip chip is also complicated to adjust... definitely not a trail-side adjustment.
Again, good, fun, fast bike... but nothing to write home about, especially for the price and complication. For anyone that has one, great buy, it is an awesome bike, but for me, there are equal (or better) performing bikes for less money. I demo's the "S" version and for $5400 you still only get a Fox 36 Float Performance, RockShox Super Deluxe Select, and DT Swiss 370 hubs (horrible and shouldn't be on this bike). Proper tires with EXO+ casings was a nice touch though.
Santa Cruz and now the new Specialized Enduro seem to place a lot of intricate shapes, parts and bearings very low and in the tyre's firing range.
Zero experience with either system, but raises some doubts for me in muddy conditions
If you just mean twin counter rotating links, then even your precious Antidote uses it as well as several others.
For most of the 2000s and early part of 2010s, when most people said VPP they meant a falling, then rising springrate and a falling, then rising antisquat where the switch from falling to rising was at the sag point. Santa Cruz themselves abandoned this years ago, and the newer low-mounted shock is even more of a move away from this.
I absolutely love my Intense Spider. Came from a YT Capra. and Spec Enduro before that. The spider and my 2104 Enduro have been my 2 favorite bikes ever.
Sold my Fugitive and am worried I’m not going to be able to find a bike as good!! After demo’ing many bikes since selling, I have realized I may have already been on one of the best in the biz. It’s not a popular opinion on here... and it didn’t really come to light until after I sold the bike and started demo’ing others, but the 157 rear end really makes a difference. Even when compared to a bruiser like the Megatower, the rear end of the Fugitive is un-flappable. Whether sticking that high chunky off camber line or staying composed and going where I wanted it to through really fast hard steep monster-trucky lines, the Fugitive just did it. Riding other bikes, I’m feeling rear end flex like I never have before.
Probably why I’m most likely going to end up on a 2020 Warden. Can’t go back to a bike without 157. Enjoy the Fugitive, never did find a limit to it’s capabilities... just my own skill!!