Yesterday I received my Duo Trap S (DTS) and promptly fitted it to my 8.6 DS DTS that I just picked up over the weekend. I assume it's similar in what its supplied with as the older Duo Trap model in that it comes with three different sized cadence bands; race, road and...I can't remember what, but easily four times the size of the middle one.

While the install was relatively easy, in particular if you have a small enough allen wrench in the appropriate size, the issue is more with the cadence magnet not being picked up. The wheel/speed sensor has no issues.

I can get the sensor to pick up if I'm about 1mm away from the frame, but any more than that and nada. Unfortunately the larger strap is just flat out too large. I'll be hitting up the LBS to see what they know, though I didn't buy from them as they didn't have any in stock yet.

Has anyone else fitted the new DTS? If so, any issues in that regard?

Hi there. I too am having the exact same problem with 2015 8.6ds .Out of the 3 cadence magnets, when fitted in the correct position. The largest magnet is too big and touches the frame. The other two are too small/far away from sensor to activate the sensor, therefore not registering cadence at all. Everything else with the bike and duotrap S/trip 300 combo is great.
Its a bit annoying as fitting the cadence magnet was the last piece of the jigsaw for me. It seems like a bit of an oversight by Bontrager. I have emailed Bontrager customer support and am awaiting reply.

I'm not familiar with this specific setup. A picture would help. Without knowing more, I can only suggest trying a larger/stronger magnet. I use a 3x12mm rare earth magnet that attracts and holds itself to the inside of the pedal spindle and lines up with the sensor. It can also be attached to the inside of the crank arm with 3m permanent outdoor mounting tape (grey foam), or adhered with some rtv silicone adhesive. I find this works 15+ mm away from the sensor.

It should be a pretty simple setup really. Trek/LBS has said they can't really do anything unless they have the bike, so I'll get it there sometime soon.

The band shown is the middle of the two as mentioned. The large band is flat out too big and hits the frame. The line on the frame is a rough indication of where the pickup actually is. Regardless of where up/down I move the band, it just won't pick up.

The manual suggests a 3-5mm gap between the magnet and frame, but with this setup, it's beyond 5mm. Nothing I can really do in this case.

While your suggestion of getting a stronger magnet, of which I have plenty, is pretty self explanatory, that defeats the purpose of this setup to begin with.

It certainly defeats the purpose of the rubber strap, but a magnet stuck on the back of the crank arm is a cleaner installation, IMO.

Of course, using another magnet would do the trick. But the sensor cost £35-40, kind of want it to work 'out of the box' . I like the neat finish of the magnet band. I bought it with the trip 300. And for the price I might have gone in another direction if knowing it wouldn't set up properly.
I emailed Bontrager customer support and got a quick response. Stating they weren't aware of any problems at the moment. And that people were using the middle size magnet (as pictured by railgun.) And also they would get back to me after speaking to management in the U.S.

Here's Trek's response...

Needless to say, there's no info to eta nor how one will submit to acquire said part. I'll follow up in a few weeks.

Haven't tried it (yet!) but hope this helps guys
Duo Trap S install on 2015 Trek DS 8.5 - YouTube

I know its a hack, but I wrapped black electrical tape to "shim" the magnet closer to the frame. I do NOT like the look, but it works.

I went to my LBS and had it installed.
They used the road magnetic cadence band (middle one) and placed a small square plastic thing/raiser to force the magnet towards the sensor.
Its very tidy and you cannot even notice that its there.
I will post some photos tomorrow or the day after

The pics i promised

i have installed several duotrap s sensors onto several dual sport series models and fx series models and never once had an issue and a comeback. the different size bands that come with the sensor are a way to gap the sensor and the magnet

Hi !
I just installed a Duotrap S sensor in my new 8.5 DS and to get the things right, I had to cut the rubber of the biggest cadence magnet - 6 mm of the inside flat part - and then I got it placed with 4 layers of black electric tape, right behind the pedal's thread end. It is now 3 mm from the frame, working well, looking good and firm, better then just the rubber band. Let's see what solution Trek comes with.

Does anybody know if there is a new magnet available yet, from Trek/Bontrager. To permanently solve this problem?

The LBS installed magnet on my FX never worked. I took it off and put three of these Amazon Magnets on the pedal spindle as someone here did. I have to tell you it looks better then the big rubber band around the crank, you don't even see the magnets. I had the magnets on hand because I had to purchase them for my road bike. That bike's Wahoo Fitness rubber band cadence magnet that is laying on some street after if broke off during a ride.

Did Trek find permanent solution yet?

Ok, this from Trek:

The only update that was made to those was in regards to the crank cadence band- but we have since included an update kit into all of the Trip 300 packaging.

If for some reason you purchase one from your local retailer, and that update kit isn't inside the box, simply let them know and they can get one from us for you.