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Home » Cycling » Stem Mount Workaround for a Bar Mounted Headlight… On an Aero Handlebar

Stem Mount Workaround for a Bar Mounted Headlight… On an Aero Handlebar

October 2014
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Imagine my horror after installing a $300 aero handlebar on my road bike and realizing the mount for my brand new Serfas headlight that I’d bought just three weeks earlier, wouldn’t work.  I was bummed.
IMG_5310 IMG_5311

I began tinkering with the mount when I noticed a large screw head at the bottom of the mount that accepts the light itself.  Just for giggles I took the screw out and checked to see if the stem bolt would fit through.  Sure enough, it worked.  My first ride with that light, I simply took the top part of the mount and bolted it atop my stem cap.  It worked well but the light mount follows the rake of the fork so that means the light shines up in the air and at 20′ in front of the bike, directly into the eyes of oncoming motorists.  Now, I didn’t buy a cheap light.  The sucker’s bright and the last thing I want to do is blind motorists as they’re passing me – most decidedly not cool.
IMG_5295

I took to thinking about ways to work around this.  First, I emailed the owner of the local bike shop and talked to his lead technician who said he’d check with Serfas to see if they had a stem mount.  After work and 2/3’s of the way through my evening ride, I stopped at the shop and Matt and I started kicking the problem around.  At first Matt used a belt sander to file the base of the mount down to an angle so it would level the light out.  That didn’t work because the bolt hole was still square and once tightened down, the light pointed up again.  Then we kicked around filing the bolt hole base down to match the angle of the light mount but that seemed shoddy.  We went in a completely different direction to work around the problem:

We took a spare Specialized cycling computer mount and modified it to accept the light mount base:
IMG_5314 IMG_5316
Notice the clip on the right is filed off as is the front lip (that was to allow the clip from the light mount to operate up and down) and the hole drilled in the center.  Here’s what it looks like when we put the two pieces together:
IMG_5317 IMG_5318
That done, I purchased some Loctite Epoxy from Home Depot, some plastic gloves and some 80 grit sandpaper to scuff the surface up:
IMG_5319 IMG_5320
The rest was simple, mix the epoxy per the instructions, lay a thick bed on the stem mount base (except where the light mount tab was going to be located – I scraped any excess out before laying the base in the epoxy so the tab would function properly). Once I laid the light mount in the epoxy bed, I added more epoxy to the sides so it would take a cruise missile to separate the two pieces:
IMG_5322And here’s the finished product:
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The key to the stem mount is an Allen wrench bolt that locks in the angle.  Simply loosen the bolt, set at the proper angle and tighten it back up.  No worries, mission accomplished and you’ve got a great way to mount a light to a race bike that A) Won’t scratch the paint on the bar, stem or the bike, B) looks pretty good (if I do say so myself) and C) works.  Now, this workaround isn’t perfect because you have to take the stem cap off and replace it to get your light on the bike.  I also won’t be able to use my computer.  So installing it will have to be done with some forethought.  That said, it sure beats the alternative:  Installing a helmet mount on the bar and have the Velcro wear the finish…  Or worse, putting a helmet mounted light on my helmet!

UPDATE:  Not so fast!  My little mount idea worked pretty well except for one minor snag and one major one…  First, I ended up leaving my computer mount under the light mount, for what reason, I don’t know but I did.  And it was a good thing.  The light is a little too heavy for the stem mount so when I hit a bump decent bump the light drooped until it rested on the computer mount.  At that point, it worked just fine and the angle was even better.  The added support from the computer mount kept the light mount on the same angle throughout my first 14 miles.  Then I stopped by the shop and I described what was happening…  We talked about possible fixes before deciding to try torqueing the pivot bolt down to see if we could get the mount tight enough.  Out on the road, on the first major bump that I hit, the epoxy cracked, loosening up the bond on the light mount.  The light didn’t drop and it took a lot to get the two pieces apart again but this would have to be chalked up to not working.  Back to the drawing board…  I’ll try a different brand of epoxy next methinks.

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8 Comments

  1. Nice. I have a set of aero topped carbon bars waiting to go on, but have been pondering a front light solution not non round bars so they’re still gathering dust in my cupboard! Only problem is where would I mount my Garmin?

  2. Niall says:

    What model of light did you buy? They look pretty good!

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