Black Mountain Cycles MCD With 650B Wheels Reviewed

The "Bubblegum Princess" with 650B's mounted

Yesterday I mentioned that I was going to be testing and reviewing some 650B X 47mm WTB Sendero tires for RidingGravel.com. Well, those went on the BgP Black Mountain Cycles rig and they have been ridden.

I thought it might be nice to put out there how these wheels feel on the new Monster Cross disc frame and fork, since the MCD bikes are so new and all. First, I better give a quick summary of what I used for wheels and tires here.

Both my 700c and 650B wheel sets for the MCD are Irwin Cycles Aon 35 GX wheels. (650B review linked) They are similar in every way but for the diameter. Same hubs, etc.... So, the only difference is tires. I used WTB Riddler 45's on the 700c set and the 650B have the Sendero tires, as previously mentioned. The Senderos are knobby, but on gravel it is hard to tell unless the roadway is packed in and devoid of chunk. Most of my ride was on chunky, fresh gravel, so I feel that the tires are of little concern in that regard.

Now, as for the ride feel of the MCD- It is smooth, but- I felt when I started out riding this thing that, the fork especially, wasn't as compliant as the fork on my cantilever Monster Cross bicycle. And I was not surprised by that, because the disc fork is beefier, and it is a completely different design. The disc fork rides well enough, but again- not cantilever brake bike smooth. I bring this point out because of what happened when I switched over to the 650B wheels and tires.

Another view. I think they look as "right" on this bike as 700c wheels and tires do.

As I said, the roads were mostly covered in fresh, and freshly graded, gravel. It was deep, loose, and rough. What struck me right away about the ride feel was that the fork was going nuts working over the surface. I don't recall that the fork ever worked like this with 700c wheels and tires. Why would this be?

Obviously the gravel had a lot to do with it, but I'd ridden loose, deep gravel with the other wheels as well. My guess is that it comes down to the different angle of attack and that 650B wheels do not roll up and over the top of deep, loose gravel as well as the 700c wheels and tires do. That said, the fork made short work of this and besides a bit of lateral movement every once in a while, it wasn't an issue. The bike just rode really nicely with these wheels.

While the fork's movement was a surprise, the rest of how the bike reacted with 650B wheels was not a surprise. I lost a bit of the "flywheel effect" of the 700c wheels. The trade off is that 700c wheels and tires take a bit more effort to spin up. The 650B wheels acceleration feel was snappier. That's a given on any 650B wheeled bike I've tried. No surprises there with regard to what the wheel size differences do to the ride feel.

Tire clearances are really good with 47mm tires. You could probably put a 50mm tire in there, maybe a 2.0"'er would slip in, but with every millimeter you go wider you lose mud clearances. The 650B wheels are slightly less in diameter than 700c wheels, so the bottom bracket is a touch lower. This never was an issue on my gravel ride, but I will have to report back once I get into some rutted out Level B dirt roads.

Otherwise, I think the 650B wheels and tires look great in the bike, like they belong. So, I will be swapping back and forth every so often. I really cannot say what wheel size is best. There are trade offs with either size which you have to be willing to live with. If I come to a conclusion there, I will chime back in. That said, if you get a MCD, I'd recommend either wheel size, and both if you can swing it.

NOTE- The Black Mountain Cycles MCD was bought and paid for by Guitar Ted. He was not asked, nor bribed for this review and that's that.