Heading into round two of our Behind the Numbers trail bikes we have the 2020 Norco Sight. If you’d like to go back and see what we looked at for our first trail bike, check out the Commencal Meta TR 29 analysis
Norco is one of the larger brands in the industry to be adopting the properly long and slack mantra that many other companies say, but don’t deliver to the degree of Norco. Their Sight was bumped up in terms of travel and size for 2020, and it points more at the aggressive, downhill side of trail bikes.
One standout feature that Norco does is evolving their geometry as the bike size changes. Dubbed Ride Aligned, there is a focus on keeping a front to rear balance for all the sizes by growing the chainstays as the front end lengthens. They even steepen the seat angles as the sizes grow to keep the rider’s weight in a more balanced position when seated. Few brands do this, and Norco deserve a tip of the cap for it.
The Sight may look like a lot of other bikes at the moment from 100 yards, and that’s mainly down to the layout. But ever since a certain patent expired, we’ve seen a lot of companies adopt this design and there are good reasons behind this that we can see from the suspension characteristics it gives.Scanning
For the Sight, as well as the others we'll be doing in the future, we filled a van with test bikes from our local bike shop, The Factory
in Fribourg, Switzerland, and headed off to Creaform’s French office in Grenoble.
Seeing as we had multiple bikes to do, one after another, Creaform’s MetraSCAN 3D was the tool for the job. The MetraSCAN is a 3D scanning solution aimed at shop floor condition in industry
, where repetitive scans jobs are needed and potentially with much larger volume parts.
The C-Track unit keeps a watch on the handheld scanner and positions it in space.
Compared to the HandySCAN hardware previously used, it requires less reflective stick-on targets to locate the scanner in space. Instead, the MetraSCAN uses an additional C-Track unit to constantly watch the scanner and position it in space, with the spherical handheld scanner having multiple reflective targets all over it. The measuring volume of the system is about 16.6 cubic meters with a single fixed C-Track.
Reminiscent of the Martians in War of the Worlds, the C-Track can be moved around during a scan session, allowing you to get into all the nooks and crannies of a part and build up the 3D data you need. And by moving the C-Track around, you can scan larger objects than if the C-Track were to stay in one position. Multiple C-Tracks can also be linked together for these larger parts or to even create a metrology room, dedicated just to scanning.
The MetraSCAN 3D was the perfect tool for doing our repeated scans on the four bikes we took to the Creaform France office in Grenoble.
Once the initial setup was done for the bikes, with a small floor-mounted jig to fix the front wheel, it was a quick and easy process to setup the next bike and repeat the scan. With the setup and expertise of the Creaform team in France, we were able to accurately scan all four bikes in less than a day and safely return them to the shop without a single scratch.
The Norco Sight comes in two wheel sizes to cater for everyone’s preference, and we scanned the 29” version. Between the wheel sizes, reach, chainstay, effective seat angle, and seat tube length are the same. It’s only the head angle, bottom bracket height, fork offset, stack, and head tube length that change.
The Sight has 150mm rear travel, 160mm of fork travel, and touts much more progressive geometry than a lot of the other trail bikes out there today.
Norco Sight Analysis Details
Travel Rear: 149.6mm
Travel Front: 160mm
Wheel Size: 29"
Frame Size: M
CoG Height: 1,100mm
Chainring Size: 32T
Cassette Cog Sizes: 50T, 24T and 10T
Norco is one of only a few manufactures to evolve their chainstay length and seat tube angle as the sizes change. As the frame size grows, the chainstays get longer in 5mm increments and the virtual seat angle gets steeper. This is a standout point for Norco and the other manufacturers doing this. These changes work to keep the rider’s mass more balanced between the contact patches both when stood and seated.
The Sight uses a Horst pivot rocker link suspension layout, something tried and tested and also fairly common in its usage today, but with good reason. Compared to last week’s single-pivot suspension design, there's a disconnect between the mainframe and the rear axle with the Horst pivot. Something that can make some faux-bar suspensions systems look like the four-bar system like the Sight, but have different curves and options for the engineers to achieve their suspension goals.
With the inclusion of the Horst pivot it now means that the rear axle moves around a virtual point in space, called the instant center. As we move through the travel, this IC moves around in space, as opposed to being a fixed main pivot on the frame like the Commencal. This ability to move the IC around in a bigger window opens up more options to adjust and balance all the suspension characteristics.
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.
Generally, the Horst pivot rocker link designs put all the suspension curves in a good starting range at the beginning of a bike's development. But that doesn’t guarantee that all bikes with this layout have good curves; it can still generate terrible curves and suspension traits. So, like with every suspension system, it still needs care and attention to have good suspension characteristics amidst balancing all the packaging, construction, aesthetics, and other concerns.
Another gold star for Norco is their Ride Aligned bike setup guide
which is one of the best out there. The online guide uses your inputs of height, weight, and gender to suggest shock and fork setups covering pressures, tokens, and damping settings but also going as far as suggesting tire pressure and cockpit setup. There’s even adjustability in the setup guide to account for your riding skill, and it includes brilliant descriptions of each skill level, even adjusting for differences in setup for riders with a more forwards or rearward riding bias.
The Sight has 18.43% progression with a starting leverage ratio of 3.22 and finishing at 2.62. Over the entire curve there’s an average leverage ratio of 2.85.
It uses a 185 x 52.5mm shock to generate its 150mm travel - just a note for when comparing back to the Commencal with its 130mm travel coming from a 50mm stroke.
The leverage ratio starts progressively until around the last third of travel where it begins to flatten out. Mike Kazimer reviewed
the Sight 29 C1 back in February and needed to add an extra volume spacer to the shock to help tune for this end-stroke linearity. Initially starting with 30% sag, the bike was bottoming out a little too often for his liking. Upping to 25% helped with this but then brought some added harshness with the higher spring rate. In the end, he settled on that one extra volume spacer and 27% sag.
The Sight’s leverage ratio curve shape is remarkably similar to last week’s Meta TR 29, with the biggest differences coming from the values. But if we differentiate the leverage ratio curve there is a sign that the Sight actually has a subtle x^3 shape to it. This is something not seen from looking at just the leverage ratio curve and is a very subtle change to the Commencal’s x^2 shape, but differentiating the leverage ratio curve is a good way to zoom in and see the minute changes in it.
The ratios on the Sight are generally higher than on the Commencal, with those higher ratios putting more force into the shock and compressing it slower, which would usually call for higher spring rates and a slightly firmer damping tune.
30% shock stroke sag gives 32.44% rear-wheel travel. Not a hugely progressive leverage ratio so falls at about 2% of each other.
Mike commented that the bike felt more planted than poppy, something that can come from suspension setup, but in the case of the Sight comes from the slightly higher leverage ratios all round. Those higher ratios would allow the shock to move more readily into the travel when faced with rider inputs or impacts.
The Norco does have 3.8% more progression than the Commencal, but it’s likely these higher ratios combined with the end-stroke linearity that can give the feel of finding the bottom of the travel a bit more often. But that relatively smoothly changing leverage ratio curve again lends itself to a predictable feel and makes the bike react well to suspension adjustments.
The Sight C1 29 comes with a 32-tooth chainring and SRAM Eagle gearing. Again, we took the 50, 24, and 10-tooth cogs as a good representation of the whole cassette.
Like a single pivot design, the Sight produces very close to straight lines for the anti-squat. For our analysis, all those curves start at the same 104% point. At 30% sag, there is 91% in the lightest climbing gear and would only result in a bit of squat from the load transfer when accelerating.
That percentage does drop as you go down the cassette, with 88% for the 24-tooth and 80% for the 10-tooth at sag.
There is a drop in the anti-squat curves as the bike goes through its travel, a bit more than the Commencal, down to just under 35% at its lowest point. But in the gears more associated with climbing there is less drop from start to finish, with the 24-tooth cog finishing at just above 55%.
The Sight’s brilliant seated position is also going to help the bike's climbing performance, not just due to being in a more comfortable position, but also balancing the rider’s mass between the contact patches more evenly than a bike with a really slack seat angle. Once pointed uphill that split between the contact patches becomes more rearward biased and the bike becomes more sensitive to the suspension squat from accelerating. The Sight’s seated position and the high anti-squat work together to statically and dynamically keep the load on the front wheel and make the bike’s long reach and slack head angle work really well when climbing.
The anti-squat may be a touch lower than the Commencal, and the leverage ratio is a touch higher, but the bike still provides a supportive feel when climbing in and out of the saddle.
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.
The Sight has 20mm more rear-wheel travel than the Meta TR 29 and so generates a bit more maximum pedal kickback in the 50-tooth gear, with 28.8 degrees in the big cog. But this then drops to 13.2 degrees in the 24T and 4.78 degrees in the 10T which is lower than the corresponding gears for the Commencal despite the extra travel.
Both the Commencal and the Norco have the same static chainstay length of 435mm and, surprisingly, they both finish with the same chainstay length of 455mm at the end of travel, despite the Norco having that extra 20mm.
If we take the same conditions as our previous test, riding along in the 24-tooth gear on the cassette and then rode off a 1m high drop that used 75% of our travel, how fast would we have to be going for the impact to not cause any pedal kickback?
In the case of the Norco, we’d have to be going 9.7km/h, or 6.1mph, for the pedal kickback to never be a problem. Only a fraction slower than the Commencal as the pedal kickback for the same parameters is fractionally less.
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.
That moving IC that we talked about can be used to generate really flat line anti-rise curves. In the case of the Sight it only varies by 1.4% from start to finish. That would mean that no matter where you are in the travel, the bike's response to rear braking would be the same. Your CoG would likely move as you went through travel, but this is true of all the other bike analyses.
The anti-rise hovers around 57% meaning that just over half the load transfer from rear braking would be counteracted. The remainder would go into having the suspension rise and could then work in conjunction with the dive in the fork to cause the load split between the contact patch to become more biased towards the front.
But there are a lot of bikes with anti-rise levels around the same as the Sight, which does strike a balance between combatting some of the load transfer from braking while allowing the suspension to move a little more freely while combatting the load transfer.
It's only the red IC dot we need to calculate anti-rise. The orange one again represents the 100% anti-rise mark.
There is a small amount of rearwards movement just before sag, 1.5mm. But from then on, it’s a forward’s trajectory for 16mm until bottom out. There is more overall movement when compared to the Commencal, but this is due to the extra travel that the Norco has. But the axle paths are again remarkably similar in their trajectory.
We once again come to the point that the Norco, while a bit more aggressively biased, is still a trail bike designed to go up, along, and down the hills. Unless the axle path is a clear driver in the development of a bike then it often comes after the other suspension characteristics and is more a result of achieving a good leverage ratio, anti-squat, and anti-rise curve.
If the axle path were to be a driving force in the bike's development, then several decisions have to fall in line with that quest for a truly rearward axle path. And contribute to many of the high pivot bike similarities in terms of suspension characteristics, layout, and packaging.
One interesting comparison point between the single-pivot Meta TR 29 and the four-bar Sight is the difference in swingarm length as we go through travel. For the Commencal, the swingarm length, or distance between the IC and rear axle, remains constant at 413mm. But for the Norco it starts with over double the swingarm length of 882mm and gradually shrinks to 553mm at the end of travel. This swingarm length effectively represents the radius of the curve at any point in the axle path, as it’s around the IC that the rear axle is rotating.
Assumptions in Analysis
For all the trail bikes we took size medium, 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 AS and AR are known and understood, it’s easier to analyze and compare bikes.