Thursday, 17 September 2009

HTC Magic bike mount - Homemade from a cat-eye headlight

So I have the very handy smartphone from HTC: the 'magic', a.k.a  the T-Mobile myTouch 3G in the US, the Rogers HTC Magic in Canada and the docomo HT-03A in Japan.

Great phone with the Android operating system and many wicked apps. Two apps I really like are the mytracks and Cardio trainer.  Both these apps are excellent for cycling - live navigation. recording your routes, speeds, cals burned, altitude, average speed etc etc and work using the GPS built into the phone. The problem is there are no products on the market (currently available)  specifically built to mount your HTC magic to the handlebar like  a regular bike computer. There are some fat ugly generic holders, but no slim well built mounting system like the guys at  make for the iphone.

Anyway I was riding my road bike and I looked down at the handlebars and saw the clamp there were my Cat-eye brand bike light clips got me thinking, why can't I rig something up with the bike light and the phone and easily attach and detach it when I go riding?. As I rode along I thought of taking off the connector piece of the light unit and gluing it the case (buying  a spare cover for the phone, which you can do) and switching them when I go riding,  clicking in  and out as quickly as it takes you to remove the standard light.

When I got home I grabbed the light which is a Cateye HL-500 - a very standard and popular headlamp for bikes. When I picked it up I discovered the HTC Magic is almost exactly the same size as the shell off the headlamp, I was emboldened. The HL-500 has two C batteries which are accessed by removing a screw and taking off the top cover of the headlamp shell. The HTC magic fitted almost perfectly into the top cover. The problem was the connector is on the bottom half of the shell and that is a lot thicker with battery partitions and the lighting fixture/reflector, but the top half is smooth and empty

The connector on the bottom half luckily is not molded on, but bolted on, so you can remove the bolt and take off the connector piece. The screw/bolt that holds it, mounts into a round shaped nut which is embedded on the internal surface of the shell, so by putting the bolt in, on the opposite side -the internal side, I then pulled on it with pliers pulling out the embedded nut. voila! I then screwed the connector piece to the top shell through the hole that is in place for the normal screw, that holds the original headlamp together. Next I got a piece of thin, netting like rubber sheet. The stuff used to hold rugs to wooden floors or on car dashboards to stop stuff slipping off, on furniture - again to stop stuff slipping. With the thin sheet of rubber I cut out a piece and laid it in the shell -cutting a small section where the volume switch is on the side of the HTC Magic (as otherwise it pushes on it and causes havoc)

I got the phone and it laid very snuggly in the cover, it was a perfect fit, like it was designed to go there and without any other fitting it stays in place, you can hold it upside down shake it and it wont fall out, its very snug and the non slip rubber sheets aids in making it tighter and creating a suction like effect and also protecting the case from scratches from the shell surface.

Also at the back end of the light cover there is a recessed section , where the switch for the old light went. This space now allows for easy access to the mini-usb port on the phone, while its in the new cradle mount.

I clipped the new device onto my bike and went for a ride - perfect. Its position on the handlebars is great. I put some small rubber bands on the top and bottom around the phone and mount for safety, just in case it bounced out - but it wasn't needed as even on bumpy sections of the road, it was held in tight in the Cat-eye shell. Not sure how a MTB trail will treat it , but on the road, its perfect. With the rubber bands for safety and for a final backup - a wrist stap connected to your handlebar and the wrist strap loop on the phone, t will keep the phone on your bike even it pops completely off its new mount.

So until they make great, slim and purpose built mount for the HTC magic, here is a viable homemade alternative that works.

The Cat-eye HL-500 -in one piece. The top half of the sheel is used to make the mount.

THe inside of the battery compartment. The round nut was removed for this recessed hole.

The bottom case with the connector removed. The screw/bolt went through this hole and attached to the round nut.

The connector now screwed to the top of the headlamp case.

The round nut, now transplanted to the top of the case, the connector is on the other side. THis is where the phone will sit.

The rubber mat laid into the case, to make it's "bed"

end shot, you can see it sits flush.

Side shot.

you can connect stuff to it while its it the mount.

you can see how well its fits- perfectly

which looks better? this ugly thing? or a streamlined cateye homemade job?


  1. That's great, thank for sharing this simple idea

  2. Thanks for a great write-up. After seeing this I ordered the same light and made a holder for Sprint HTC Hero. The Hero is a touch wider and I had to Dremel down some of the ridges on the sides, but it works great. Thanks!

  3. Dean,

    This is totally unrelated to this post. But I happened to come across your post on one of the ACL rehab forums.

    I have had the same surgery and am feeling stiffness on the knee when I sit in the chair for a long time. Do you have any idea how long this may last?

    Please revert back to

    Many thanks from india.

  4. Hello Dean,

    Thanks for sharing this. I'm currently looking for some sort of mobile phone-gps-cycle computer all in one gadget.

    Your post confirmed my suspicion that I could get all this from an HTC smartphone. I'll probably buy the HTC hero, as it's the latest and greatest. Only one doubt remains: do I need an internet connection in order to use My Tracks and Cardio Trainer?? I know gps works on its own, bu the maps?? are they downloaded before hand, or as needed? If you need internet connection that means having a mobile internet plan in the contract, but from what I've seen, those are only offered at the higher end plans... 1200 minutes.. i certainly don't need/want that. So, how does it work?

  5. Sorry for the long delay guys, posted this story and forgot about the blog.

    Boris - I used the Google tracks function in another country, where I had no data connection - no maps - but the gps worked fine and all the data was recorded and once I got back home I could see the maps.
    I guess you could do the same with Cardio trainer, or just zoom out far so the maps doesn't update all the time. I dont think you can preload the maps, they are updated as you use it. You could use wifi connection after you ride to check the maps and zoom in on you exact path - all the data will be recorded.
    I live in Japan - My plan is in two parts the cell phone calling part and the data part - I have a unlimited use plan for the data, so I never worry about anything I use my phone to its fullest watching youtube and downloading things with impunity.