this thing has the WORST instructions ever...can anyone tell me what the thing on the spoke is supposed to line up with? the fork attachment has both an arrow and some strange diagonal ridges but when i attempt to line it up with either of them i still get no reading on the computer...

Make sure the sensor and magnet are just about as close as you can get without them touching, like 2-3mm.

It's kind of a finicky thing, the magnet/sensor connection window.

Like --> <-- this close.

EDIT: Also found this: https://www.performancebike.com/help/...20Computer.pdf

They say 2mm max distance between magnet and sensor.

another question: will this work the same on my back wheel? i was hoping i could still use it while riding on my trainer

The thing on the spoke is a magnet, hold in place by a small screw. The center of this magnet should be aligned with a line engraved on the fork attachment. Most importantly, the spacing between the magnet and the attachment must be very narrow, like 1-2 millimeters. The following 3 steps installation guide is for a Vetta C-500 but your Ascent should follow the usual way to fix them.

STEP 1
Clamp the bracket around the handlebars and tighten in place. All Vetta cycle
computer brackets are designed to work with 26.0 - 26.4mm standard
diameter road handlebars. Shims are provide to fit smaller 25.4mm mountain
and road bars. Make sure not to over tighten the bracket as this may result in
breakage. The bracket only needs to be tightened enough to keep it from
spinning on the handlebar during normal riding.
STEP 2
Loosely, mount the C-500 transmitter to the leading edge of your left fork
blade using the flat rubber block and the 2 zip-ties provided. The arrow
printed on the side of the transmitter should be facing the spokes and pointing
toward the bracket on the handlebars.

STEP 3
Attach the spoke magnet to the wheel, and adjust the alignment of the magnet
and transmitter so that the magnet passes the transmitter within 1-2mm of
the small line molded into the lower part of the transmitter and the word
MAGNET printed on the side of the transmitter.

Won't work with the transmitter on the back wheel. Too far from the receiving head. I know it is only a couple of feet but still too far.

Easiest way of knowing is to try it! Mount your bike on your trainer, take off the front wheel, go just besides the bike rear wheel and spin the front wheel while holding it in your hands. Then see if your computer has registered some distance. Or ask someone to watch it while you spin the wheel. If it works, move the attachment and the magnet to your rear wheel...

As bikeaday said, the chances are that it won't work. But then, why not give it a try ???

ok it seems like everything but the speedometer works now...

Did you calibrate it to your wheel size?

calibrated. finally got it to work, just needed to line it up better. thanks for all the help!

Well, actually I could be wrong. What I did try a few years back, sensor mounted on the fork and a second head display on the rear handlebar of a tandem. Didn't work, too far from the TX. I guess the distance from a rear wheel mounted sensor would be about the same.