Monday, May 4, 2015

MC286 component considerations

The logical choice for components for the MC286 is to install a road drivetrain and a set of mountain bike wheels because 142x12 rear wheels for mountain bikes are readily available for reasonable prices. It turns out one of the great challenges of making this frame work on a reasonable budget is the incompatibility between 11-speed road cassettes and mountain bike hubs.

When 11 speed was introduced to road components a couple of years ago, it required a slightly longer freehub body. (Note that this is all just from reading rather than experience; my road bike is still at 9 speed.) Mountain bike components didn't introduce 11 speed until more recently, and so far they have stuck with the old freehub body dimensions. This means that using a standard mountain bike wheel won't work with an 11 speed road group. There are very few road-specific wheels available with a 142x12 rear axle at this time, though I'm sure that's likely to change soon enough. The 142x12 standard is relatively new to cyclocross bikes and to my knowledge is not used anywhere (yet) on regular road frames. I suspect most cyclocross bikes being sold by the major brands that include 142x12 rear axles are using proprietary wheels. Because this standard is being introduced on higher end bikes, there aren't likely to be many budget-oriented options right now.

I did a lot of research and considered several options for wheels:
  • Use a mountain bike wheel with the new Shimano XTR 11 speed cassette and a road group. Aside from the high cost of XTR, this may not be workable because it's only available with a 40 tooth large cog, which likely exceeds the capacity of the road derailleurs. This could become viable in the future if Shimano were to offer more options (in price and gearing ranges).
  • Use a Campagnolo 11 speed cassette. According to this article by Lennard Zinn, the Campagnolo 11 speed freehub bodies can fit on most 10 speed road hubs. However, this requires finding a hub that has both 142x12 and a Campagnolo freehub body available as options. I don't know whether this exists, and if it did, it would be very expensive and also quite restrictive in the available gearing ranges.
  • Find a wheel specifically built for cyclocross and through axle wheels. Right now the only thing I can find off the shelf is the Stan's Iron Cross wheelset. The new DT Swiss 240S DB hub is also designed exactly for this purpose, but I don't know what the cost is, and haven't yet found any wheels for sale based on this hub. In both cases, however, I think the cost is higher than what I was hoping to spend.
  • Use a standard mountain bike wheel and install only 10 of 11 cogs from the road cassette.
As far as I can tell, only the last two options are even likely to work, but the last option has many more price options available because there are so many wheels available for 142x12 29er mountain bikes. I ultimately chose the Mavic Crossride wheelset because it looks like a good reliable set of wheels and is half the price of the Stan's wheels.

For components, I considered Shimano 105 and SRAM Rival and eventually settled on Shimano 105 because in part because I was able to get a great price on the complete group without brakes from in Germany. They were one of the few retailers I could find anywhere that offered their road groups with brakes optional, and they also had a great price on the Mavic wheelset I wanted. Starbike's prices are such that I'm sure they would have been competitive even a year ago with shipping from Germany to the US, but the strong US dollar vs. the Euro right now made the price even better. For two wheelsets, two component groups and several other miscellaneous parts, shipping was only an extra 10 Euro for what turned out to be two very large boxes. The parts arrived in less than two weeks.

This is the drive side of the Mavic rear wheel. The freehub came with the sticker on the right wrapped around it, warning against using cassettes that use individual cogs as opposed to a carrier. I got a 11-32 cassette with my Shimano 105 group, which uses individual cogs for the first 8 cogs and a carrier for the last 3 cogs. The reason for this warning is the aluminum construction of the freehub body. Individual cogs will eventually dig into the splines of the aluminum feehub body, where the carrier spreads out the load and avoids this. Using the cassette that I have chosen will therefore have a risk of damage to the freehub body over time, particularly in the middle cogs, which will be subjected to more torque than the smaller cogs. For now I'm going to accept the risk and try it for a while.

This is the complete 11 speed cassette set in place on the freehub without the lock ring. The last cog spins freely in place because the splines are not tall enough to engage it. In addition, the threads do not extend far enough to properly engage the lock ring. It's possible to get it on, but it will only catch about 1/4 turn worth of the thread. So, it's clear this won't quite work.

The excessive stack height of the 11 speed cassette is made clearer by attempting to install the wheel with the whole cassette on it in the frame. The picture on the left shows all 11 cogs in place, and the picture on the right shows only 10 cogs. With 11 cogs, the lock ring rubs against the dropout so that it would not be able to spin with the cassette, and the smallest cog is so close to the dropout that even without the lock ring problem, the chain would likely rub against the frame. On the right, there is enough space for everything to work properly, just with one fewer speeds. Because the first two positions each require special cogs, doing this properly requires buying both a 12 tooth first position cog and 13 tooth second position cog, and using them to replace cogs 11, 12 and 13. However, someone wishing to not buy the cogs could theoretically just remove the 13, leaving a 11, 12, 14 ... combination, which would leave an unusually big jump in gearing between the 12 and 14. The picture above shows the 12, 13, 14 combination, which added an extra $20 or so in costs, but made it possible to keep the total cost of the bike down by quite a bit.

The last important consideration for this bike is tires. The Miracle Bikes web page for this frame specified that the frame could handle a 38 mm tire. I went ahead and bought some 37 mm tires and installed them on the rims. I looked at a lot of tires trying to find a balance between smooth center for riding on pavement and some kind of tread on the sides for riding off pavement. I decided to try the Continental Contact, which is really more of an urban/commuting tire. Here it is installed in the frame.

My first reaction is that I wanted something wider than this and there appears to be a lot of room. By my measurement the tire is closer to 32 or 33 mm. I measure about 50mm between the stays, and similar clearance at the bottom bracket and top of the fork. This made me wonder if I could have gone wider and knobbier, so I'm going to try a set of 40 mm tires instead.


  1. Hello, thanks for blogging about the mc286. I am looking to do the same as an entry level cyclocross bike. Ultegra 11 speed with QR Fulcrum 5 CX wheelset and canti's. Do you have any insight into how stiff this frame is compared to anything else?

    1. I don't check comments very often, so sorry if this is no longer relevant. The bike feels as stiff as the carbon road bike I have and stiffer than the aluminum road bike I used to have. Those are really the only reference points I have. The MC286 is only going to work with through axles and disc brakes, so canti brakes and QR wheels will require a different frame. I believe Miracle Bikes does make such a frame, though.