So this is a nice specific post then. If you are looking for a bit of intel on how to fit a Bontrager
On the other hand, if you’ve come for some general road cycling entertainment, then these are not the droids you’re looking for, Move along now.
So, for the roughly 0.1% of you that own a Trek bike with a hole in one of the chain stays, here’s a guide to installing a
And now an additional THIRD thing as I update this post. I madez a video. It is, after all, 2020, and we are stuck in our houses. So, either watch this YouTube dispatch, or continue to read and look at the pictures, your choice.
Yes, you are welcome for all the value I am giving you.
(Note: Some of the links in this post are affiliate links. It you click and buy something, I get a commission. You pay the same price.)
Step 1: Buy a
Duotrap Speed and Cadence Sensor
Bad news. The sensor doesn’t come with the bike. That thing in your chainstay is just for pretend (see step 2). I’m sorry to be the one that has to break this to you.
If you want one, you’ll have to shell out some cash. It costs around $60 / £40, depending on your monetary persuasion (okay, where you live…).
Here are the links:
Once the sensor arrives, you can move on to…
Important note: this post deals entirely with the Bontrager
(And if you need to buy a
Step 2: Remove The ‘Faux’
My guess is that the Trek design cadre didn’t want to sell a bike with a fug-off great hole in one of the chainstays. Instead the bike comes with a plastic ‘thing’ that resembles a Duotap, just without all the sensory gubbins.
Remove that by unscrewing the little screw on the front with a small hex key (or Allen key in my language) and then easing it out of the hole towards you (update: the bolt requires a size 2.5 Hex wrench/Allen key).
It’ll come slow and steady because the hole in the chain stay that faces the wheel has a rubber collar that fits quite tightly around the little plastic arm that you’re removing.
Step 3: Put The Battery In The Duotap
Hmm, this is disappointing. After using three photos in step two, I don’t seem to have a shot that shows the battery going in.
Anyhooze, it’s no great challenge. It takes a CR2032 battery, the flat round one about the size of a 10p / a quarter.
Step 4: Insert the Duotap Into the Hole In The Chain Stay
It should be pretty obvious how you insert the actual
Once the one true
Now it’s time to let the sensor see the magnet.
Step 5: Fit The Magnet To A Wheel Spoke
Like pretty much every other speed sensor, the
Some reviews suggest that the spoke magnet doesn’t come with the
If your one doesn’t come with a spoke magnet I wouldn’t worry too much. It’s a very small part that any bike shop should stock (and which they may well give you for free).
For this magnet (which I do think is the Bontrager one), you clip the two hinged sections of plastic around the spoke then tighten with a flat-headed screwdriver.
In terms of positioning, the idea is that the magnet passes as close as possible to sensor in the chainstay without actually hitting it on the way round. Prepare yourself for two photos that show essentially the same thing:
In case it’s not obvious, its the cylindrical arm that protrudes through the back of the chainstay that is the sensor.
I was a little bit concerned whilst fitting the magnet that it wouldn’t go close enough to the sensor. The spokes on my Domane have flattened profiles rather than being cylindrical (presumably because Trek know that I want to eke every ounce of performance out of this thing). This means you can’t fit the magnet in any direction other than flush with the spoke (ie. you can’t rotate the end furthest away from the spoke towards the sensor)….
…. Which turns out to be no problem whatsoever. The sensor arm picks up the magnet in this orientation. Panic over.
Step 6: Fit The Magnet To The Pedal Crank
This is more straightforward. The magnet that attaches to the pedal crank (which helps record cadence) definitely comes with the
The magnet is integrated into a glorified rubber band. You put this over the end of the pedal crank and move it down until it’s at the point where it passes the
Enough talking. Foto:
I think circle in the middle of the
As an aside, those two little dots to the right of the cadence sensor, before you get to the ANT+ logo, are lights. They flash (green and red I think) when the magnets on the spoke and pedal crank pass within range of the imperial probe and indicate that the
All that’s left to do is….
Step 7: Pair Your
Duotrap With The Cycling Computer O’ Your Choice
My choice is now the
Since you might have a different device, I’m not going to say much, other than that pairing the
Whatever your bike GPS persuasion, I’m sure you’ll be interested to see a photo of my
There you have it. Everything you could possibly want to know about how to fit a Bontrager
If you found this post because you’re looking to buy a
If this sort of thing (i.e. instructions for esoteric bike accessories) floats your boat, you should sign up to my mailing list to make sure you don’t miss out on future posts.
If this sort of thing doesn’t float your boat, but for some reason you’ve still read to the end of this post, you should still sign up for my mailing list because I mainly write about more interesting things (plus you’ll get my free guide to completing your first long distance sportive).
Until next time, safe cycling!
29 thoughts on “How To Fit A Bontrager Duotrap Speed and Cadence Sensor”
I’ll actually read this later! 🙂
Mike Killen liked this on Facebook.
Mine came with the spoke magnet, pedal magnet and a battery. The only thing that wasn’t clear in the instructions provided was whether the battery was to be inserted face-up or face-down.
Thanks Lev for clearing that up.
This is what I’m not clear on either can someone pls advise which way it goes?
Hi Linzey, I’ll take a look and let you know. I might even do a quick video.
Hi Linzey – I did a video. Here it is: https://youtu.be/uY2Ltm3My6c. In short, as you open the battery compartment, the positive side of the battery (a CR2032) needs to face up towards you.
Mike Killen liked this on Facebook.
Sorry but with a gps Garmin who’s telling you the speed ? The GPS or the duotrap sensor ?
Hi Tony, I think (think) it’s the GPS first and then the speed sensor if you lose signal. That said, when I’m on the turbo (chance would be a fine thing) the head unit certainly knows to show the speed derived from the sensor when the GPS is showing me not moving (I don’t switch the GPS off). Maybe it just uses what appears to be the most sensible reading. Anyone else know?
Hi Tony. It’s actually the other way round, at least if you’re using a garmin sensor like the one attached to my rear hub. Because the GPS can be unreliable, especially when riding through trees etc and the signal from the wheel updates more often, the on-bike sensor is the master and the GPS is the slave. You’ll notice the difference if your wheel sensor drops out and speed updates go from quite constant to updating every second or so!
1. I have a duotrap S…2. and the dummy spot is on the inside of one of the front wheel forks… Cant figure how this will work and my trek doesnt have a dummy spot at the back wheel.
The S model looks totally different than what you are showing.
Any ideas? I am thinking that I bought the wrong item.
Couldn’t get mine to work….then turns out the battery that was sent with the unit was flat! Grrr! Once I had changed that, it synced up instantly. Thanks for clear instructions.
Awesome. Saved me an expensive shop visit!
Good to hear Bob 🙂
What if my cadence is not being picked up by my computer? When I start my ride it the computer indicates that is has found 2 sensors but I don’t get any cadence reading?
Hi I am having problems with my node 1, older I know but it should still work. I replaced both batteries and nothing is working, no lights, no cadence, no speed , just temperature. Any ideas folks?
Best description of how the Duotrap should be installed. This was so precisely written and the pictures were a perfect compliment. Thank you.
Thanks, great information!
Damn! my S won’t fit, despite the shop telling me it would. Back to the store tomorrow. Thanks for the guide
A great help to see how it is put on and put together. One thing missing in the description is the small rubber stopper(?) that goes in over the top of the little screw which holds the sensor in place. If you are taking Duotrap out after someone else fitted it (eg LBS like in my case), the screw is not visible because of the little rubber stopper, which can be removed with a finger nail or sharp implement. Just push it in when re-installing the Duotrap. Everything else you need to know is here.
Hey, thank you for the information. Much needed since I just purchased a Trek with about half the goodies….and don’t know anything about how to get it working. Much appreciated. I’m sure I’ll be asking questions once I get all the parts together and try to get them working.
No problem Phil. Hope you’re enjoying the new bike.
Have had continuing problems with the cadence sensor rubber band slipping or breaking. Finally resorted to using a zip tie around it. Suboptimal but grew tired of buying replacements.
That was a fun read! And Helpful too.
Mike – you have gone straight to the top of my Best Email Address 2021 leaderboard.
Straightforward and Concise , thans.
Will the duo trap s sensor work with a iPhone app?
I have the original Duotrap (which was ANT+ only) but I can see that the Duotrap S is both Bluetooth Smart and ANT+. iPhones can connect to Bluetooth Smart sensors, so it should work with iPhones (unless there is some esoteric reason why not, which I’d estimate at a 0.00000001% chance).