I tried my old cord with my new gps on the bike and it works fine although without the traffic. That's fine for the bike, I'll save the traffic input for the cage.
...but I like your idea of the cigarette lighter/usb adapter. I took a quick look at Amazon for what they had, but the reviews weren't great. What and where did you get yours?

 

The OEM Garmin Power cord has a surge protector built into it. The OEM Power cord is also used as a FM Antenna to Broadcast FM out if you have that option ... My Garmin has a USB IN also (Model 755) that can be used as a Power In, although it was made for Updates, it works fine for power supply (FYI).

I soldered in a second power point (almost the same as a cigarette lighter) inside the fairing to the extra supplied power wire near the head light (that wire is prewired with a 20 amp fuse in the fuse box). Then I permanently pluged in the Garmin Original power supply cord to the power point (wire tied) and ran the wire out by the gages.

Then I bought an Iron Aces Garmin Mount (I Phone also) and mounted the Garmin over the gages (see their web site / pix (Road Glide only)

http://www.ironacesspeedshop.com/pro...-gps-mount.cfm

Then I did the radio conversion to have a AUX IN at the rear of the radio for a No Wire Look into the front of the radio - Iron Cross can do the AUX IN (rear) if don't want to do it yourself ... AUX IN Front will still work as well.

The Iron Cross Chrome mount will also require a Ram Mount Garmin Cradle attached to it ... (very secure !)

Now I have an Above Gages Garmin /MP3 player solidly mounted with quick unmount and all the wires are nearly hidden ... Garmin turns on with power to the bike and shuts down when the bike is turned off ...

I bought a bunch of USB cigarette lighter/power point powers cords ($5 each) and use them on my John Deere, Vette, Boat ... and the the OEM Garmin power cord stays on the Road Glide hidden inside the fairing ...

 

The cigarette lighter USB adapter I got from target for about $15, it is a flush mount type with two USB ports and only sticks out about 1/8", I don't have the model number. The cable cost about the same, I ordered this one: http://www.gpscity.com/3br-powerspor...18-inches.html. Some one on here made a post on this setup, that's how I found out, but I can't find the post again. Also when I was at target I saw they had short USB cables (to late I already ordered one), but the mini side was straight, not bent like the one I bought on line, that shouldn't matter though and it was cheaper. So drop by target and check it out.

 

I have a Garmin 1450LMT also that I had jury rigged on an 05 Heritage. I'm looking for a 90 degree low profile female connector to go into my cig lighter on my 2012 FLHTC so as not to hit gas tank on hard left turn. As far as shortening the cable I am pretty sure you will lose your traffic alert feature. My.02 cents.

 

There is no traffic were I ride, if there was, I wouldn't be there.

 

Yeah I don't think you can cut that without losing the traffic feature of your Garmin.

 

I haven't checked into it so I don't know for sure, but that lump is on lots of wires for lots of things and every time in the past it was to help match the impedance, you should not really need that. Cut into it, I bet you find it is only wires coiled around the outside of the main wires, not touching anything, only smoothing out the voltage as it passes through (sort of speak). Many times it is just a metal tube encased around the wires. This case may be different, but I have been using one cable or another without it for a long time and it has never affected my traffic feature.

 

My 450 mount and cord, the cord black coiled rubber started breaking down...

I replaced it with a new wire and shortened it to about 8".
Only had a Red and Black power wires.
The plug side into the mount had a 4 prong connector thouigh..

no traffic, no bluetooth...just a GPS

 

I have done it but ordered an extra power cord from Garmin so I can use it in my truck also. Mine is about 8" long now. Plugs into a Powerlet on my bars.
Ratkiller

 

I see you have a Roadglide too. I installed an extra 12v outlet and an AUX audio in the left glove box for the GPS, cell phone etc. I just coil up the extra cord in the glove box and leave enough slack outside to turn the bars full left and right when the GPS is connected. There is a good post on here somewhere about installing the extra AUX on the Harmon Kardon head unit. You could also get a cord on ebay without the traffic receiver for short money and modify it. I got one just for the bike to limit my loss in case it gets stolen since I leave the cord in the glovebox.