Technical FAQ: All about drivetrains

This week, Lennard Zinn answers readers' questions about all things related to drivetrains

Bottom bracket bearing cups

Dear Lennard,
I have a S-Works SL3 frame that I love and was wondering if you could answer a question for me on the bottom bracket.

The bike is two years old and the bottom-bracket was creaking and had some play. I took it apart and found that the bearing cup on one side (drive side) was loose and the other one was tight to the frame. I looked at the Specialized installation manual and it appears that both of these cups should be snug to the frame. I asked a bike mechanic at Peloton Cycles (where I purchased the bike) about this, and he said that the cups are supposed to be glued to the frame and they will come loose and need to be re-glued. He said to use “liquid gasket” to re-glue it.

So, given that I can find nothing from Specialized about using glue to seal the cups, am I getting the right advice from Peloton or should these cups be snug to the frame by design? Secondly, if it is correct to glue the cup to the frame, can you recommend a specific “liquid gasket” product to use and also a specific grease to use for the bottom-bracket?

Dear Robin,
Here are the answers and also some helpful links from Specialized:

The shop is correct but recommended the wrong item for the job. The PF cups should be bonded in using 3M DP420 or 460 (420 = 20 min working time, vs. 460 with 60 minute working time). The BB shell of the frame and the outer surface of the PF cup should be cleaned with alcohol or acetone. The “bonding agent,” the 3M product should then be applied to the bb shell, the PF cup put in and then grease the bearing contact surface of the PF cup and press in the bearings, install the crank and let it sit for 24 hours before use. The 3M product is just a gap filler. As we know if anything has come loose in the carbon BB shell there is likely to be some sort of wear, especially if left for any period of time or usage. The PF cup will still be able to be pressed in or out of the BB shell as it doesn’t adhere to the Delrin material the PF cup is made from, only to the carbon surface of the frame.

Specialized manuals (you can pick the language and then view any tech manual we’ve ever made).

Link to the install guide.
—James Stanfill, Specialized Bicycles

Campagnolo gearing options

Dear Lennard,
I switched from Record double to triple a few years ago to handle the steeper hills especially in the Dolomites, like the Lavaredo or Monte Zoncolon. At age 65 and counting I need lower gears. At home I use 53-42-30 and 11-25. On our hill to the ski area, I use the 30-23 for the 10 percent sections, saving the 25. Last year for a European bike trip, I found that a TA Specialites 28 granny in front and IRD a 11-30 10 speed worked in back with a Centaur triple rear derailleur. Same chain length even. Just don’t cross-chain! For a new bike, I would like to avoid the triple if possible, for weight and maybe for shifting.

What do Campy-equipped pro teams do for lower gearing besides just going to Compact? Maybe 34×29 is plenty low enough for them on any hill?

I hear Shimano and SRAM parts have been switched about to get 34×34 maybe with XT cluster and rear derailleur and road shifter. Compatibility issues.

I have been staying with Campy since 1996. Any ideas or rumors of new stuff? I see Campagnolo’s website lists an Athena 3×11 now, but the largest cog is still only 29.

Dear Eric,
Yes, Campy-equipped teams only ever go as far as 34-29 for the lowest gear. And a 29 remains Campagnolo’s largest cog.

Chain/rear derailleur noise

Dear Lennard,
I’m running a Frankenstein setup for my road bike. Using 10-speed Campy Veloce ergo double shifters, Dura-Ace front derailleur with FSA Energy compact crankset. Rear is a 11-34 SRAM PG1030 with Shimano SLX M662 long cage rear derailleur (made for a 9-speed mountain bike) with a JTEK adapter. Also a new 10-speed KMC chain. So I installed everything OK and replaced the rear cable. Shifting is fine and hi-lo adjustments seem OK.

The only issue I’m having is the chain is making excessive noise on the lower jockey pulley. It seems like the chain is not feeding straight or the chain doesn’t sit on the pulley very well. Typically on the 11t it’s noisy. Derailleur hanger does not look bent and derailleur cage looks ok. Any suggestions would help.

Dear Jason,
I would start by actually checking that rear derailleur hanger alignment with the proper tool, like the Park DAG-2. When your rear derailleur is wrapped so far to take up the slack on the 11-tooth cog, the jockey wheels are close to be one directly behind the other, and alignment is critical for them to be quiet.

SRAM Force WiFLi

Dear Lennard,
Regarding Niaz in your last post, I would recommend our Force 10-speed WiFLi options, including the 11-32 cassette. It’s a more affordable option and would only require a new mid-cage RD, chain, cassette, and chainrings. Also, SRAM Force remains one of the lightest groupsets available, and much lighter than the triple setup with all the gearing range, as you pointed out. We never want to discourage the purchase of a new groupset, but certainly want to remind people of all the available options.
—Michael Zellmann, SRAM Road PR & Media Manager

11-speed triple derailleur

Dear Lennard,
“Eventually, I imagine Ultegra will be available in an 11-speed triple configuration. At that time, you could buy an Ultegra 11-speed triple rear derailleur and interchange its jockey wheel cage with the cage on your Dura-Ace 9000 derailleur.”

What is an 11-speed triple rear derailleur? Does it have the cages spaced further apart than an 11-speed DOUBLE rear derailleur? Or is this a typo?

Dear Ashok,
It’s a rear derailleur designed to work with a crank with three chainrings in the front and an 11-speed cogset in the rear. It would be identical to an 11-speed rear derailleur for a double crank, except that the jockey wheel cage would be longer.

Shimano brake cables compatibility

Dear Lennard,
I was just wondering if BC-9000 brake cables (Shimano) are compatible with 7900 brakes. The packaging has a warning that the 9000 brake cables should be used only with 9000 series brakes being that they are Teflon coated. Is it really possible for the cable to slip from the fastening bolt? Is the design of the fastening bolt different between the 7900 series brake and the 9000 brakes?

Dear Ernie,
Former VeloNews technical editor Nick Legan saw your question published here and reached out with the following answer:

There is a reason that the warning is on the cable packaging. The 9000 series cables are not compatible with other brake systems. Nor is it possible to retrofit the BR 9000 clamping mechanism to older brakes. So for now, only 9000 brakes are compatible with 9000 cables.
—Nick Legan, Shimano spokesperson


Editor’s note: The final question in this column, relating to Shimano brake cables, initially included an answer from Shimano’s Wayne Stetina, in which he claimed that the 9000 cables and BR 9000 clamping mechanism were compatible with non-9000-series brakes, though “it seems all the test riders always torque the brake cable fixing bolt tighter than official Shimano torque specs.” Shimano’s Nick Legan followed up on that answer with the above recommendation that 9000-series components are not compatible with other Shimano braking systems.