Ask a Mechanic – Knocking Noises, Replacing Cables and Lube

This is the third edition of a weekly column we’re running here at Art’s Cyclery 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 daniel.slusser@artscyclery.com.

Question: I hear a knocking noise only when climbing, what is it?   From: Anthony

Answer: Anthony, when opportunity knocks sometimes you just want to tell it to shut the hell up! Knocking tends to come from sloppy bearings. This means the source of the noise could be the headset, hubs, or bottom bracket. First check each of them to see if they are loose.

Click on this picture to see an instructional video on how to tighten your headset.

Click on this picture to see an instructional video on how to tighten your headset.

To check the headset, pull the front brake and rock the bike forward and backward. If you feel slop then your headset needs adjusting. For your hubs, make sure your skewers are tight and then push the wheel from side to side in the frame and fork to check for play. Also check the freehub bearings in the rear hub by pinching the largest cog and moving it from side to side to check for play. This same procedure can be performed with your crank to check for bottom bracket play.

If each of these tests reveals nothing, I would pull the crank and check the bottom bracket torque and the condition of the bearings. To check the bearings, make sure they spin freely and do not have any side-to-side play.

Lasly, make sure your chainring bolts are intact and properly torqued as this is a common cause of knocking sounds. Check your pedal torque too.

If your bike is a full suspension mountain bike, then inspect the linkage bearings for play, loose fasteners, and general damage.

Question: How do I know if my cables on my Trek Madone 5.2 need to be changed? I have had the bike for a year and about 3,000 miles. I want to do all the work myself and I don’t know how hard it will be and how to change out the cable if the cable is in the top tube of the frame!   From: Jonathan

An oil-based lube like Tri-Flow works well to extend the life of your cables.

Answer: Jonathan, it is time to change the derailleur cables for sure. With respect to your brake cables, replacing them depends on how much effort is required at the brake lever. However, if the inner brake wire is white with corrosion, you are overdue for replacement. Oftentimes brake cable life can be extended by applying an oil based chain lube to the housing. This helps to break up corrosion and dirt that cause friction. As far as your internal cable routing goes, the difficulty of getting a cable through depends on a couple of things.

If your bike uses full length housing, then you have nothing to worry about. Simply pull out the old housing while leaving the inner wire inside the frame. Now just put the new housing over the old cable and through the frame before removing the old inner wire and replacing it with the new one.

If your bike does not use full length brake housing but instead has a housing stop at each end of the top tube, the best way I have found to install a cable is to use a flashlight to look inside the tube and then use a hook that I have fashioned from an old spoke to grab the cable once it is in view and then pull it out of the exit hole. If you don’t have a spoke to use, sometimes small needlenose pliers will do the trick.

Thankfully, manufacturers are getting smarter with how they do their internal cable routing, making it easier on all of us.

Question: Why is it that every time I come near my bike I end up covered in grease? How much “dry lube” does my chain need? And why do they call it dry lube when the wet stuff gets all over everything?   From: Paul

Answer: Paul, is dry lube an oxymoron? Personally, I’m not a real fan of the stuff as it seems that most “dry” lubes offer little in the way of actual lubrication and instead tend to mask the mechanical noise generated by friction within a drivetrain. With that said, some dry lubes are better than others, but I stick to the wet stuff even though I never ride in the rain.

Lube your chain every 2-3 rides to keep you and your bike happy.

Dry lube has a tendency to build up on your drivetrain components making everything greasy as well as adding weight to your bike. I once had a customer put so much dry lube on his bike that his rear derailleur was completely encased in the stuff. When the chain entered the derailleur it was completely sealed off from the outside world until it exited out the bottom! A friend of mine used to work at a shop that had a heavily used rental fleet that used a wax based lube exclusively on each of the bikes. The mechanics at that shop collected the hardened wax buildup off of each of the bikes when they returned and generated a ball of wax that approximated the size of a softball at the end of the summer season!

Chain lube in general only needs to be lightly applied every 2 to 3 rides in order to properly protect your drivetrain. More than that and you are likely only making things worse. When I deal with overlubed chains the gloves go on so my hands stay grease free. You may want to pack a set of nitrile gloves to put in your saddle bag in anticipation of your next mechanical. You will be glad you did, as they are light and take up almost no space yet make that energy bar you eat after changing that flat taste so much better.

Question: After a bad rain road ride – what areas need to be addressed on the clean up? The chain – derailleurs – etc… should I spray any lube in the shifters under the hoods, headset or other sealed bearing places?

Answer: Fred, these days water is not the big threat to bikes that it once was. Most bearings are sealed so well they can practically be submerged without issue. Unfortunately this means an awful lot of bearing seal drag exists in a modern bike that becomes a source of parasitic power loss. From a mechanic’s perspective it is a shame really because a little preventative maintenance would solve these issues but alas, the marketplace has dictated otherwise. My lamenting aside, you have little to worry about.

Dry off your bike after your ride and lube your chain with an oil based lube that will displace water and work as a rust preventative. If you really want to be fastidious you can spray your chain with WD-40 to blow out the water. That is what this oft derided stuff was originally designed to do, hence the name WD for Water Displacement. If you go the WD-40 route, let it evaporate overnight and then apply your choice of oil based chain lube. Of course it goes without saying that if your frame is made out of steel, you should also shoot a little WD-40 into the vent holes to keep internal rust at bay.

Lubing the shifters is a good idea as well. Simply spray a half-second sprits of Boeshield T9 into the mechanism and you are good to go. If shifting is still sluggish, oil the cable housings as well.

Lastly, it is a good idea to put an oil based product on bolt heads such as the stem top cap bolt where water tends to pool in order to prevent rust in these areas.

Other than these steps you should be fine as long as the bike was assembled with a healthy dose of assembly lube (i.e. bearing covers, skewers, seals, metal on metal contact points, etc.). If you ride in these conditions often, you may want to have your hubs and headset overhauled more often to stay ahead of damage that water can cause to these areas, but no additional work to these areas directly following a rain ride are necessary.

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.

2015-03-20T13:03:30-08:00