How much drag does a baby trailer add to your bike ride?


Getting out for a bike ride has been hard as a parent, but we got out with our toddler and took her on a trip up Old Tunnel Road the other day. I was curious how different climbing would be with all of the extra weight, so I flipped on Strava to see how my timing and speed compared.

I don’t have a great base for comparison, because I usually ride without Strava, and on the rides that I was using it (or a GPS), I was riding with a different bike.  Also, we stopped twice because we ran into a friend (hi, Greg!) and had to avoid being attacked by wild turkeys.  Seriously.

Here was my setup:

  • Bianchi Axis “commuter bike”
  • Thule Chariot Cougar (1-seater) ~25lb
  • 1 baby, ~24 pounds


Either way, it was interesting to look at the differences in times:



The stretch in question is a 1.3 mile stretch, with 369 feet of climbing and a 5% grade.  I was pushing pretty hard, and based on the times above, I think I could have ridden the stretch in maybe 9:45 with my commuter bike if I was not towing a child.  So, I’d estimate a 30% increase in duration for a steady climb with the trailer.

How’s the math work out?  The Chariot Cougar added about 50 pounds, so if I did my math right, that is:

50 / 2.2 * 9.8 * 369 * 12 / 39.37 / (13 * 60 + 9) = 31.8 watts of lost power

My total weight, plus bike is probably about 185lb, so 50lb is about a 27% increase, which matches pretty well with my estimate.  That totally ignores differences in friction/drag for the trailer and other energy losses, of course.  Maybe I just got lucky?  It’ll be interesting to see how much slower things are on the flats.

How did our daughter do?  She started to get a bit impatient during the climb, probably because it was taking a while.  We took a break at the top and then descended.  She seemed to enjoy the descent.  I guess she enjoys going fast and the bumps?  I turned back at one point, asked how she was doing, and I think she said “wheee”, so that’s a good sign.

Which heart rate monitor with GPS should I buy?

(This is a work in progress.  I’ll continue to update it as I can, as I proceed with my search.)

After going a few years without training with a heart rate monitor with GPS, I’ve decided that it’s time to look into getting a new one.

I still own a Garmin Forerunner 310XT that I hope to never use again because it’s been fairly terrible.  I used my Forerunner primarily for running, but did some cycling with it as well.  It was probably an 80%/20% split.  I originally chose the 310XT because of its long battery life, and of course, for its heart rate and GPS features.  I had previously run with an old Polar, maybe a S625X?  It worked pretty well, but I was intrigued by the idea of using GPS to track my workouts.

In theory, based on the features, the 310XT was a cool product, but in practice, it was burdened by awfully buggy firmware that made it unusable most of the time.  I’ve had such a profoundly bad experience with that watch, that I’d rather not buy another Garmin device again.

What am I looking for?

I’m looking for most or all of these features, not necessarily in any particular order:

  • Logging for post run/ride analysis
  • Easy data transfer from device to a PC or phone for analysis
  • Strava integration
  • Reliable performance
  • Non-creepy data storage.  I’d like to not have to rely on a company’s website to look at my information, and I’d like to choose whether that information is private or not.
  • Good heart rate measurement
  • Good GPS
  • A decent display for monitoring heart rate, total distance, current speed, and so on
  • Battery life: 8 hours would be great, so that I could use it on longer bike rides.
  • Waterproof, because I sweat a lot.  I don’t really swim, but riding and running in rain happens not too infrequently.

So, what’s out there now?

I bought the 310XT in early 2012, and the Polar many years before that.  Things have changed a lot, and there are new players in the game.

My phone

My iPhone has GPS built in, and if I want heart rate data, I can get a “dumber” device that measures my heart rate and have it sync with my phone.  I usually don’t run with my phone, though, and on longer bike rides, I’m concerned about battery life.  So I’d prefer to look for something different.


Fitbit has a wide range of devices available now.   On the higher-end is the Charge HR and the Surge.  The Charge HR is their “Active Fitness” device, and the Surge is their “Performance fitness” device.  The Charge HR will track steps and heart rate, but has no GPS.  The new Blaze just came out too.  It has a heart rate monitor, but does not have an embedded GPS.  One nice thing about the Fitbit devices is that they can measure heart rate without the chest strap – a sensor is part of the wrist band.

One can use any of their devices, or none at all with their app’s “MobileRun” Feature.


I’m not going to buy a Garmin, but I still am interested in knowing what their product offering looks like.

Their vivofit line includes 3 models of interest.  The Vivosmart HR contains a heart rate monitor that measures from your wrist.  It does not contain a GPS.  The vivofit vivoactive does contain a GPS, but has no heart rate monitor.  The vivofit vivovactive HR has both, and would probably be the device I’d consider if I were considering Garmin at all.

Garmin also offers a fenix series.  Only the fenix 3 HR contains a heart rate monitor and a GPS receiver.  All of the other fenix models (fenix 2, fenix 3, fenix 3 sapphire) have various levels of GPS functionality, but do not have a wrist-based heart rate monitor.


Suunto wasn’t ever high up on my list, but I wanted to see what they have to offer.  Browsing their website, I found three models that may fit my criteria.  The Traverse, the Ambit3 Vertical and the Ambit3 Peak.


Working on it..


Working on it..


Working on it..