If you're tuned in to our Instagram page, you saw our recent post with the new Aivee MP4 hub. These were kind of a surprise delivery, as we'd been expecting a center lock version of their top-end Edition One hubs, but these hit first.
The easiest comparison is to one of our favorites, the Aivee MP2. The MP2 came onto our radar as a simple, reliable, durable, high performance hub that had a lot of boutique hub characteristics at an OEM hub price level. They've become a popular option, whether in GOATs that are headed mostly for gravel or AForce discs going out on a group ride.
MP4s are all that, with several improvements. You won't be surprised to hear our particular enthusiasm for the color choices (orange, red, blue, black). They also have a slightly lower overall weight (435g/set vx 460g/set for MP2), with a harder alloy in the hub shell. Fans of quick engagement will be happy to learn of the 40 point engagement THR free hub system, which is more important the lower the gears you use. Like the MP2, all of the popular axle formats are supported, as well as Shimano/SRAM HG drive, Campagnolo 8/9/10/11 speed, and SRAM XD. The MP4 is available right now with XDR 12 speed compatibility, while the MP2 will only get XDR later this year.
I'm about to build our test set (rhymes with orange, pictured above) into my RCGs for all sorts of use. Notably, this will be my first go-round with XD, although plebeian that I am it will only be 11 speed. Alas...
Builds with MP4 hubs will be posted soon, with prices at $70 more than MP2 builds. The February carbon disc pre-order closes overnight tonight, and if you want to get in on that order with MP4s, let us know. We can make it happen but we'll need to scribble the order on a dirty napkin to get the timing right.
And now a quick note about XDR. XD has been around for a few years. SRAM made XD for wide range 11 speed mountain bike applications, and now uses it for 12 speed wide range mountain bike cassettes as well. The big innovation is that XD allows use of a 10t cog, instead of the 11t cog which is the smallest cog that can fit on a Shimano road (aka "HG") free hub. XDR (XD"Road") enables 12 speed cassettes for road gear ranges. XD cassettes can be used on XDR free hubs, just like 10 speed road cassettes can be used on 11 speed HG free hubs. They even use the same 1.85mm spacer to pull this off. Going the other way - fitting a 12 speed XDR cassette onto an XD free hub - doesn't work. The good news is that if you have a White Industries or I9 XD road free hub, notice that spacer? Yup, they've been XDR compatible for a while.
And now a quick note about engagement speed. Engagement speed is basically how many degrees does the hub need to move through in order for the drive to engage. Notice that I emphasized "hub" in that last sentence. The number of degrees your hub goes through per degree of pedal movement changes with what gear you're in. If you're blasting through a critical corner in 53x13, a 40* engagement hub will hook up in roughly 10* of pedal motion. That's pretty freaking quick! But if you're in 42x42, as I will be nearly constantly in my XD setup, the hub turns just 1* per every degree of pedal movement, so a 40* engagement hub takes 40* of pedal movement to engage the drive train. I use a 36x48 easiest gear on my mountain bike, and that makes high engagement speed pretty nice indeed. And that's why we SO often say that very high engagement doesn't much matter for road, but that it does definitely for mountain bikes and also some for gravel and wherever you're going to be on and off the gas in low gears.
Which nicely brings us to our next piece of new hub day news - Industry Nine's Hydra hub. The Hydra drive has an amazing half degree engagement. Hydra replaces the Torch mountain bike hubs which have been a favorite for the last couple of years. These are $60 more than the Torch hubs they are replacing (Torch rim- and disc brake road hubs are staying as they are) and we will be updating the site to reflect the new hubs soon.
So then, new hub day.