FIRST IMPRESSIONS | TEARDOWN
Stan's M-pulse Hubs & Flow CB7 Carbon Rims
Why someone would consider buying Stay's CB7s over another carbon wheelset. There are many justifications that folks will rank in making their own choice, and we're in this beautiful spot now with high-end bike components where once a rider's prepared to outlay the necessary lucre it's rare to be proven wrong.
Many wheel features, especially compliance, which Stan's also claims is a focus of their carbon rims, are verified by a mist of anecdotes and impressions. Claims always come with caveats attached; your mileage may vary. This is a first look at a wheelset I'm testing from Stan's NoTubes and I want to lead off by discussing two areas that it's superior to other choices.
- Easy Tubeless Tire Inflation
- Low-drag Coasting
How these two features rank against the most generous warranty, the most alien aesthetics, claims of Herculean survivability, or a western country of origin, is entirely up to the purchaser to decide. Many hours in, they aren't likely to be the whole story of this wheelset.
Easy Tubeless Tire Inflation
This carries over from Stan's aluminum rims. Tire fit is rarely a Goldilocks tale, but from the baggiest 29" Maxxis EXO+ to the tightest, slightly-tiny Schwalbe 27" Super Trail, no rims consistently air up a tire like Stan's. I don't even pull the Presta valve cores when inflating these with a floor pump, which I do for every other brand of rims on the market.
This is thanks to Stan's BST, or Bead Seat Technology, which is still the best tubeless-ready system going. It's combined here with a significant rim offset to even out spoke tension for a stronger wheel system.
I'll still recommend a DT EX511 over a Stan's EX3 for the anti-insert trail smasher looking for the most durable rim, but the truth is that most mountain bikers are more stressed about over-inflating tubeless tires than they they are about turning their rims egg-shaped.
Stan's M-pulse wheels use Project 321's magnetic drive system. I'll write more about the intelligent updates that the Stan's-specific hubs have received over the P321 G2 hubs that I'm still riding but, at the end of the ride, it's the same system. And one thing that everyone I know who's ridden these hubs agrees on, is how drag-free they seem to roll.
As with a slightly-rubbing brake rotor or turning the cranks in a low gear with a shitty chainline, it's questionable what difference this feeling really makes to wattage, but psychologically it's amazing going back and forth.
The M-pulse uses Project 321's 6-pawl 1.66° engagement system. After a foray into engagement adventurism I can say definitively that super-fast engaging hubs feel better for me on the technical trails I seek out on the Shore.
Carbon rims come in unusual profiles that differentiate them from aluminum hoops. Here I'm thinking of the rolling waves and 7.5° spoke angle of We Are One's Convergence rim (rim only 475 USD) or the wild single-wall Zipp 3Zero Moto (rim only 750 USD).
As with these rims, the shallow Stan's Flow CB7 (rim only 600 USD) has been engineered with compliance in mind, but aesthetically, until I'm right up close they look almost identical to an aluminum Stan's Flow rim. I'm all in on this sleeper look. Take the blend of weight savings, dent-elimination, and reportedly-improved radial compliance and lateral stiffness the carbon rim offers and package it simply.
My favourite feature of Shimano's XT M8130 LinkGlide drivetrain is the increased availability of the Hyperglide (HG) freehub standard. Stan's, of course, sells these wheels with XD or MicroSpline freehubs as well. I have an HG freehub body so I can run the Flow CB7 setup on a couple of different bikes.
The M-pulse HG freehub body is also compatible with 11-speed road cassettes. In practical terms for us mountain bikers, that means you need to run the, included, 1.8mm spacer behind your Shimano mountain bike cassette, regardless of how many gears you have.
The North America-made P321 free hub bod, is a great place to jump into how this hub differs from a Project 321 G2. There are two nice, subtle, upgrades and one obvious downgrade.
I have two P321 G2 hubs in regular use. A single-speed hub, run as a 6-speed, on my gravel/commuter rig and the hub I originally reviewed for NSMB, starting in October 2017. I have serviced both hubs a number of times. Since every one of the pawls has a powerful magnet attached to it, it can be a bit tricky reinserting the freehub body into the drive system as they all want to slide out and stick to the drive ring.
Stan's has solved that little niggle by capturing the pawls in the freehub with a small retaining ring. It's such an elegant solution that I expect we'll see it when the newly-Canadian P321 launches the production version of its G3 hub.
The other upgrade on the M-pulse hubs I quite like is the preload system. It's not as stealthy and clean as the inline design on the P321 G2s, but it's much simpler to use with the wheels installed on my bike - which is when preload should be adjusted. These hubs spin so smoothly out of the box that I'm at a bit of a loss to differentiate them from other high-end hubs like the Industry Nine Hydra.
Now about that clear downgrade. The Japanese EZO bearings that come as stock in the Project 321 G2 hubs are excellent. In my experience, they spin more smoothly and last much longer than the Enduro bearings shipping in most high-performance hubs, including the M-pulse.
At the same time these feel like the smoothest hubs I've ridden with Enduro bearings, so for me, it's a question of how they hold up, in particular to our North Shore winter conditions.
All hub-bearing systems are preloaded, but how they are preloaded falls into two categories and there are dogmatic followers of both. Personally, I like to judge hub designs individually, since I've seen catastrophic examples both ways.
The M-pulse hubs, like the P321 G2 or Chris King, use adjustable preload via a locking collar. This allows the rider to tune how much the hub bearings are preloaded to maximize how freely they spin. The negative is that this preload needs to be adjusted to achieve optimum performance and some hubs have issues with coming loose.
You are more likely to encounter the system used by Industry Nine Hydra and 1/1 hubs, DT Swiss hubs and many others. These use a carefully-toleranced internal spacer to support the bearings as the hub itself is preloaded by tightening down your frame or fork axle. The setup is totally intuitive, and the only preloader to come loose is your frame axle, but there's no perfecting your hub's drag by micro-adjusting bearing tension.
I'm a setup nerd and I prefer the pros of an adjustable bearing tension system over the simplicity of a non-adjustable system. I appreciate why many riders would rather not have the added intrigue that a tuneable preload collar can bring to the trailhead. Preload at home folks!
It's early days on these wheels but I can say definitively that they air up easily with a floor pump as I expect from Stan's rims, and they spin supernaturally and engage lightning fast, like my P321 G2 hubs, which makes perfect sense.
I'll be back with more to say once I have enough hours on them, but in the meantime here's more information about the M-pulse & Flow CB7 carbon wheels (1987 USD | pair) and the Flow CB7 rim (600 USD | each).
Height - Steve Buscemi-ish
Wait - Patiently
Ape Index - T-Rex
Age - The same as DOS
Favourite Song(s) this week - I'm Your Man. Nick Cave (covering Leonard Cohen)
Favourite Colour - Cosmic Lilac
Bar Width - It depends
Reach & Stack & ETT - It depends
Crank Length - 175mm except when it's 170mm
Wheel Size - Hot For Mullets