Thursday, June 29, 2017

Broken Spoke on Mavic Ksyrium ES Anniversaire

Broke a spoke & didn't even know it...  Rode around for couple of weeks like this.  Because of the missing spoke, the wheel isn't round and the rear brake has been dragging...


Turns out Mavic made quite a variety of wheels with similar spoke designs but not the same.  So there's a pretty big variety of spoke designs, spoke lengths, spoke end designs, etc.  Measured the approximate length of the spoke (can't see how much it extends into the wheel so estimated...).

Bought a replacement spoke online from a Bicycle store in San Luis Obispo (Art's Cycle) and the special spoke tool from a Chinese company.  Turns out that the spoke wrench doesn't fit my wheel!  (both ends of the wrench don't match...)

The old spoke adjuster is stuck and broke apart...  Will have to drill it out!  (I might take the tire off before I do that...)
First, I took a cutoff wheel (on an air tool) and cut the broken spoke flush (center punched the middle for drilling).  Yes, I took the tire off before drilling...

Drilled a small hole and used a splined remover tool to try and spin the left over threaded portion of the nipple out of the wheel.  It worked for a couple of rotations (with repeated seating of the remover tool with a hammer) but stripped out.  Drilled a larger hole to use the next size up remover tool.  After about 20 times of hammering in the tool and spinning the left over part a little bit at a time before it would slip, it finally came out.

The threads were not damaged but it looked like it had corroded together to some extent.  The threads are reverse ("righty loosy").

I don't have a reverse threaded tap set so I'm not going to mess with the threads in the wheel.

Installed the new spoke to this point (hand tightened about 3 threads, so at least I know that the threads are correct and not cross-threaded).  At this point, there's going to be pretty high tension on the spoke so the nipple will need to be turned with a wrench.  (I put some grease on the threads so that it will install easier and hopefully won't corrode together.  I don't think it will back out.  There's going to be quite a lot of tension on the spoke.  I'll put a small pen mark on the nipple/rim to check if it rotates after riding...)  The length of the spoke is correct (!).  But, I don't have the right tool for this special design nipple.  It's got 7 splines and is just a little smaller than 7 mm (6.8 mm, as measured using dial calipers).  I'm ordering a Park Tools wrench that's supposed to fit (via Amazon).  We'll see when it gets here... (still not done!)  But wait, there's more.  The nipple on the replacement spoke appears to be the same basic design as all the other original spokes on the wheel, but the diameter of the nipples are not the same!  It looks like I'm going to need two different special wrenches for the one wheel!  (I have no idea where to get the right wrench for the original spokes...  Will have to do more research...  Those French and their special nipples!!!!)

I adjusted the new spoke and now the wheel runs nearly true.  Without this one spoke, the wheel was WAY out of true (lateral runout of about 0.2 inches).  Now, that the spoke has tension on it, the runout is about 0.03 inches, I'm guessing...  I had to keep in mind that all the nipples are reverse threaded (lefty-tighty...)!

It's good to ride now.  The runout is pretty easy to tell because of the very narrow clearance to the brake pads on a road bike (usually only about 0.1 inches).  Test rode last night and the wheel runs pretty close to true and with the brakes adjusted, does not rub on the pads.


The Park Tool wrench is on the new replacement spoke with a 7-spline Mavic nipple with about a 6.5 mm OD.  The other wrench (Chinese made brand) is on one of the original spokes on the wheel, which has a 6-spline Mavic nipple with about a 5.5 mm OD.  Thus, to adjust the spokes on this wheel, both wrenches are required now!

The cheap Chinese tool had to be hand filed because the shape for the splines was inaccurate.  I used some very small jeweler's type of files to make it fit the 5.5 mm 6-spline nipples.  I got it to work.  But, because of the lack of strength in the design of the wrench and the poorer quality material used (probably with no heat treating), the wrench bent while using it (can be seen in the picture).  It worked to turn the nipples but was bending (The nipples require quite a lot of torque to turn them.  The threads of the nipple and the wheel rim threads appear to have some "sticktion" due to some corrosion...).  Park Tools makes the wrench for the 5.5 mm 6-spline nipples also.  I'll have to buy that one too...

Finally, got the tool at the bottom of the picture.  It does the same job that the cheap tool at the top of the picture does.  All this to turn the spoke nipples on one wheel!