Review: Stan’s Flow MK4 wheelset – Now with magnets
There are 29” and 27.5” versions of the Flow MK4 wheelset, or you can buy it as a mixed wheel setup – Stan’s sells front and rear wheels individually on their website. The front wheel is priced at $308 and the rear is $657, for a total price of $965 USD.
The rims are backed by a 3-year warranty against manufacturing defects, although that doesn’t cover you if you end up two feet short of a road swerve. If that happens, Stan’s has a one-year crash replacement policy that gives riders 50% off a replacement rim. As for the hubs, these are covered by a 5-year warranty against manufacturing defects.
• Wheel size: 29 inches or 27.5 inches
• Intended use: trail / enduro / DH
• Rim material: aluminum
• Rim width: 30 mm (internal)
• Hubs: M-Pulse, 1.66° engagement
• Rear spacing: 12 x 148 or 12 x 157
• Weight: 881g (front) / 1039g (rear) / 1920g total (29″)
• MSRP: $965 USD / rim only: $129 USD
• More information: notubes.fr
The new Flow MK4 rims have an asymmetrical profile, which allows the same spoke length to be used for the entire wheelset, eliminating the need to have multiple spoke lengths on hand just in case. These 32-hole rims are constructed from 6069 aluminum, with a welded joint and reinforced spoke bed.
They are laced to the hubs with a three-cross pattern using Sapim D-Light spokes and alloy nipples. I prefer brass nuts to alloy because they are less prone to rounding off during adjustment, but they aren’t as common on pre-built axles these days. The internal rim width is 30mm, a number that has practically become standard for trail and enduro wheels, as it works well with tire widths from 2.3″ to 2.6″.
What sets the new hub apart is the use of magnets on each pawl. Small circular neodymium magnets pull all 6 pawls up in the drive ring, a design that Stan says provides better engagement with less drag. And yes, it’s based on the Project 321 design – the Oregon-based company makes the freehubs for Stan’s. Personally, I’m a huge fan of the fact that there are no miniature springs under each pawl, as these seem to jump and bounce into the darkest corners of my shop exactly when I don’t want them to.
All 6 pawls are angled so that two at a time engage with the 72-tooth drive ring, which equals 216 points of engagement, or 1.7 degrees of rotation between engagements. In other words, there is minimal crank rotation to engage the hub. It’s not as fast as I9’s Hydra hubs, which only have 0.52 degrees between engagement points, but it’s not far off, and it’s one of the engagement hubs the fastest on the market.
This wheelset was ridden in the wettest and driest times of the year here in Washington, so it was exposed to the full gamut of mud puddles and moon dust. For most of the testing period, it was a Stumpjumper EVO alloy, with a Maxxis DHR II DoubleDown rear tire and an EXO+ Assegai front with no inserts. My typical pressures were around 21 psi front and 23 rear, changing slightly with conditions. Installing the tires was a breeze and everything fell into place without any issues.
ON THE TRACK
I have reviewed several different iterations of the Flow wheels over the years, and each time, “neutral” is the word I use to describe the ride feel. They aren’t crazy soft or crazy stiff, making this one of those wheelsets that doesn’t dramatically offer the ride feel of a bike. Now, “middle of the road” might not be a marketer’s dream product description, but when it comes to wheels, it’s a great place to be.
The suspension and meaty tires do a lot to disguise the attributes of the wheels, and it takes something radically different to deliver a tangible difference. Still, I could notice the slightly smoother ride quality of these wheels compared to the WTB CZR carbon wheels I had before. Aluminum wheels tend to have a slightly more damped quality than stiffer (and more expensive) carbon options, and that was certainly the case here. There was no harshness and they were nice and comfortable on thick, brake-filled trails.
This time around, it’s really the hubs that are the main talking point. The quick engagement is most noticeable at slow speeds, in technical sections of trail, the type where you take a half pedal stroke here and a half pedal stroke there. Whether super-fast engagement hubs are better than hubs with more moderate numbers is up for debate, but riders looking for near-instantaneous response when pressing the pedals will find a lot to like in M hubs. -Pulse.
Even with this high engagement, the sound emitted from the rear hub when freewheeling isn’t unpleasantly loud – it’s audible, but not bothersome at all. Riders who prefer super loud hubs could probably apply a lighter grease or oil to the pawls, but for me and my sensitive ears the decibel level was ideal.
A rubber seal on the non-drive side end cap would help improve the water resistance of the hub.
The rims themselves held up well, with only one small dent in the rear wheel after many hard miles. As for the overall build quality, I had to add more spoke tension after a few days in the Whistler bike park. It’s not uncommon, since those brake bumps seem to shake just about anything, although I will say that historically I’ve had more wheels from Stan needing attention than, say, DT Swiss wheels . The Flow MK4s don’t have crazy high voltage to begin with, so it’s important to keep an eye out for them, especially if you do a bunch of shuttle or park bike rides.
Most bearings roll smoothly except for the non-rear wheel side bearing. This one has developed rust around the perimeter and feels a bit gritty. Again, these wheels have seen some very wet rides, but I think a rubber seal on this side of the axle might help improve the water resistance of the hubs.
+ Quick-engaging, easy-to-maintain hubs.
+ Very neutral ride feel – neither too stiff nor too soft
– Spoke tension dropped dramatically halfway through testing
– Hub sealing could be a bit better for really wet conditions