Ask a Mechanic: Ultegra Di2 on CX Bikes and Hub Troubleshooting

Welcome to our Ask a Mechanic column where our expert mechanic Daniel Slusser answers your bike maintenance questions. If you have a question for Daniel, please post it on our Facebook Wall or e-mail Daniel directly at

Question: Even though ‘cross season just ended I am already dreaming up my race bike for next year. The new electronic Shimano Ultegra group looks perfect for ‘cross since it doesn’t have shifter cables to get contaminated in the dirt and mud. The problem is that I want to use a 1×10 setup. Is this possible with Ultegra Ui2 or do I need to use a front derailleur for it to work?  From: Andrew

Your electronic dreams can come true, Andrew! Unlike Dura-Ace Di2, the new electronic Ultegra group does not house the brains of the system in the front derailleur. According to Chad at Shimano American, each component has a chip built into it to guide its function independent of the other parts. This makes it possible to use a 1×10 setup with only a right shifter if you so desire. With Ultegra Ui2 coming in at a price lower than mechanical Dura-Ace, I expect to see it at a lot of ‘cross and amateur road races next year.

Shimano Ultegra Di2 6770 Shift/Brake Lever Set

Dreaming of running electronic shifting on your cross bike? Consider a 1×10 setup with Ultegra Di2.

Even though ‘cross sensation and current national champion Jeremy “J-Pow” Powers rides for SRAM which does not currently have an electronic group, I can imagine J-Pow at some time in the future spinning one of his personally made DJ tracks featuring a derailleur servo sample. I can hear the future of ‘cross shifting and it is at the core of a techno-house track.

Question: I have a pair of Mavic Kysrium SL wheels that are about 4 years old and I am having some problems with them. The front hub feels loose and has side-to-side play that I can’t seem to adjust out. Also, my rear wheel makes a weird noise at high speed, but the noise goes away when I slow down. I can’t figure it out. Any ideas?  From: Mark

Answer: Like the hands of the clock, so are the wheels of our lives. They continue to turn day after day with little thought given to them until their movements cease to smoothly advance or simply halt altogether. Mark, I am afraid the bearings in your front hub are shot. But, at least they made it four years before giving up the ghost.

With respect to your rear wheel, the noise problem you are experiencing is quite common with Mavic hubs. The bushing that the freehub body rides on is either dry, contaminated, or worn out. It is catching on the hub intermittently at high speed and generating the pulsing sound that you are experiencing.

Thankfully, the fix is simple. Remove the skewer and cassette before removing the cover/face of the non-drive side of the axle that is held in by an o-ring. Inside the axle you will find a hex broach for a 10mm allen wrench. With a 10mm allen on the non-drive and a 5mm allen on the drive side, unscrew the axle in order to liberate the freehub body from the hub. Be careful as you remove it because there are loose pawls inside that will spring loose only to disappear into the ether. After removing the freehub body, clean the inside with degreaser. Do the same with the pawls.

Mavic M10 FTS-L Freehub Body (Shimano/Sram)

Mavic’s steel freehub bodies are tough to wear out and are cheaper to replace than an entire wheelset.

Once everything is clean, lube the bushing in the freehub body and the springs with hydraulic brake mineral oil or 5-weight suspension fork oil. Lube the rubber seal that contacts the back of the freehub body as well. I know this type of oil is an unusual lubrication recommendation but Mavic recommended this to me years ago and it really does work well. Any other lube will damage the bushing and/or cause it to catch the hub at high speed thereby creating the problem you are trying to fix. The recommendation makes sense because suspension fork bushings are lubricated using the same product.

After reassembling everything (don’t forget the washer inside the freehub body) if you are still experiencing the same problem or notice excessive play, then the bushing is worn you’ll need a new freehub body.

This will silence the specter in your rear wheel and return you to the blissful paradise from which you were wrestled; a station where time and miles pass by nearly unnoticed beneath your wheels.

Daniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly University. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.