My Secret Weapon: Best Bike Split

by | Dec 1, 2016

It seems that my last post has created a bit of a stir so I thought it best to quickly follow up and share with you how exactly I ‘cheated’ my way to the club records.  My “something else’ is a piece of software called Best Bike Split.  I believe that this software is that good that it is tantamount to cheating.  But, before I lose any more friends, let me say straight up that it is NOT actually cheating. It is legal, UCI approved and used by a number of pro-teams.  In this post I will explain (in an obscene amount of detail) what it is, how I use it and why it makes such a difference to TTs.  I will also share with you how to make it work effectively on a Garmin.

I am also delighted to report that I have arranged for a discount of 25% off Best Bike Split (normally $119 per year) for unhinged cyclists that have signed up to my email list.  Please note that I DO NOT make any commission from this offer.  I will always be open with you about this sort of thing.



What is Best Bike Split?

Best Bike Split is a piece of online software that lets you plan your pacing strategy for a Time Trial.  It is a very simple idea that requires a pretty complicated model to execute but that is what they have done.  Best Bike Split takes a whole bunch of parameters including your position/bike fit (or wind tunnel data if you are so fortunate), the course, your FTP and weather (forecast and historical data) and uses them to predict your time for a given race.  It is pretty accurate even with bike fit data that is estimated.  Better still, it then breaks down the TT into a series of intervals to show you how to pace the race.

Race Intervals – why are they important?

It is easier mentally

it is much easier to focus on hitting 25 intervals of different lengths and power than it is to ride for 1 hour time at a single power level. This is particularly the case when the going gets tough.

Imagine sitting on your turbo and having to ride for 60 mins at 300W. What about if you had to ride for 5 mins at 280w, 2 mins at 320, 30s at 350, 1min at 100 and so on, averaging 300w for the hour? Which would you find easier? (Feel free to substitute a higher or lower number than the 300).

In my experience it is much much easier to break down a big effort into shorter intervals.

Optimal TT pacing

We have a fixed amount of available power to put in over a given time period.  How should we distribute this power? Evenly? Negative-split? What about when there is a headwind in one direction?

We should be pushing slightly harder when the going is tough and easing off when the going is easier. This might seem counterintuitive and we are entering the realms of head-fuck territory here. It is explained well in this article.

For me, the best way of thinking about it is that you will obviously be spending longer amounts of time in the slower sections of a course. Therefore, if you can put a little bit more effort (power) into these sections than you will get a relatively greater overall return (higher average speed) than if you put more effort into the faster sections. It is also takes relatively more power to raise speed incrementally from a higher starting point.

Still confused? Let’s just assume that you definitely want to put more effort in when it is harder to maximise average speed. This includes going into the wind and going uphill. Even the flattest TT courses will have slower and faster bits, be it slipways, slight inclines, roundabout complexes and headwinds etc.. The genius of BBS is that it models the lot and comes up with a power plan for the race.

Lets talk about power

Yes, you do need a power meter for this but, to be frank, if you don’t have one then you are probably at a disadvantage anyway.

I will caveat this as I know that some testers pace perfectly well based on experience and feel and don’t use power data to race. There are not a lot of them though and I am really directing this article to the less experienced club TTers out there who are not averse to a bit of ‘cheating’ to go quicker. So if you want to go quicker, buy a power meter. You can then use Best Bike Split and the welcome side effect is that your training will generally be more focussed and effective if your train with power.


Overview of Best Bike Split

In this section I will give you an overview of the Best Bike Split and how it works. I will use a time trial that I did on 14 July this year on the ‘Sleeches X – Mayfield’ course as an example.    I will show you how to generate the race plan and get it onto the Garmin.  I will then go on to compare the actual results with the plan.  It was one of my best races of the season where I broke the club course record.



First of all you would set up a basic profile in the software as shown.

Best Bike Split Profile

My Profile

Key info in here will be weight and FTP for the model.


Bike Profile

You then set up profiles for your bikes.

Best Bike Split Bike Profile

My TT Bike Profile

It looks complicated but is pretty simple to set up and it will spit out the all-important estimate of CdA (co-efficient of drag). If you have bike fit data then you can enter that. If you have wind tunnel data then you can also enter that to put in your actual CdA. You can use actual race data to refine your CdA numbers in the model. I have done that in the numbers above.  I think that I am pretty ‘Aero” for a big guy but I will let others with more knowledge comment on that.



Next step is to create your course in the system by uploading a .GPX or .FIT file


Best Bike Split Course - Sleeches - Mayfield

Sleeches – Mayfield Course


Once your course is in, it is in so very easy to plan for future races on that course (5 minute job).


Race Plan

Next up we are going to create the race plan. We select the course, bike and select some options on road surface and terrain.

Race Profile

Best Bike Split Create Race

Creating the race

Weather Model

Next up we get the weather model.
Best Bike Split Weather

Set Weather

Using the advanced weather option in Best Bike Split will give you a detailed prediction of what the conditions are going to be like.  The closer to race day you do this the more accurate it will be.  Updating it is super-easy. To get the best results we want the exact start time on your race day or as close as possible. The above gave us a gentle cross-wind so no dramas at all. It was a fast day.

Generate the Race Plan

Model Parameters

Once we have the weather in we can go ahead and generate the race plan. We have a number of model options here: Normalised Power, % of FTP, Goal Time and Training Stress Score.  I tend to use the NP model and set FTP at about 105-110% for a 10 mile TT. For this race I went for an ambitious 350 Watts of Normalised Power.  (NP is a calculated power number that attempts to better quantify the physiological cost of a variable effort.  More explanation can be found here).
 If you had a target time in mind you could input this and see what power you needed to do to hit it.
Best Bike Split Created Race Plan

Generate the Race Plan


Best Bike Split Output: The Power Plan

We then get the following output:


Best Bike Split Power Output

The Power Plan

The graph shows the various intervals (in Watts) against distance along with estimated speed and the elevations.


The Time Analysis Tool

Best Bike Split Time Analysis Tool

Time Analysis Tool showing the effects of a 10% increase in power


This is a very useful tool.  It lets you play around with the model to see what would happen if you put more power out (as above).  You can also look at what gains you would make if you dropped a few kg.


Race Overview

Best Bike Split Race Overview

Race Overview


The race overview in Best Bike Split gives us the race prediction.  We can see that the model is predicting a time of 26mins with an average power of 325w and normalised power of 340w.  This is a little bit lower than the inputed goal. You can go back and re run the model if you wanted a bigger number but I was broadly happy. These numbers are achievable for me so lets have a look at the intervals in more detail.


Race Intervals

Best Bike Split Race Intervals

Race Intervals


Slap me round the face with a wet kipper and call me sad, but this is the bit that I get really excited about. ‘All’ I needed to do is deliver 31 intervals of varying power within what I am physically capable of and I would get a decent time.  This course is a good case study as it is rolling. It may surprise you to see so much variability in power detailed above but one of the main reasons that I am moderately successful as a tester is that Best Bike Split allows me to push much more than I would naturally do when the course is slower and ‘recover’ when the course is naturally quicker.  This results in a higher average speed. Simples.

What is not so simples is how you can use this data practically. I mean, who can recall 31 intervals when you are on the limit and barely able to remember your own name?

Best bike split helps us out here too with the cheat sheet:

Best Bike Split Cheat Sheet

Cheat Sheet


This gives you a broad power or speed target for various course characteristics and can be printed and stuck to the top tube.  I have used this for very long solo efforts but you are not really getting the best out of Best Bike Split in this way.  What would be really nice would be to get the race intervals onto your GPS device and have the intervals displayed.  Again Best Bike Split is kind enough to accommodate.


File Downloads

Best Bike Split File Downloads

Various download options

There are a whole bunch of ways you can now use your race intervals.  I will talk about the Garmin options in the next section but it is worth highlighting a few others:

  1. TCX Power Route – allows you to load the plan into ride with GPS to get a look at where the intervals are on the course.
  2. Zwift – I have not yet used this but see huge potential here to run simulated races.
  3. TrainerRoad – this basically sticks the power plan into TrainerRoad format so you can run a simulation on the trainer.  The image below shows how I used  this earlier in the season when I had to miss a club TT for some reason. The race simulation allowed me to counteract the feeling of ‘they are all getting faster while I am not there’.  I am sure that you will find it no surprise that it is way more harder to do these races on a trainer.


Best Bike Split - TrainerRoad Workout

Best Bike Split – TrainerRoad Workout

I had a pretty good attempt at this but, you can see that I did not/could not hold the power on the Wattbike towards the end of the race.  The new integration of Best Bike Split with the Wahoo Kickr or use of a smart trainer would have probably helped here as the power would have been controlled for me (if I was capable of handling it of course).

So this is all a very positive blog thus far but now we have to get the intervals onto the Garmin in a useful format.  And this is most definitely not simples. #burnmygarmin


Using Best Bike Split with your Garmin

One of the reasons that I dislike my Garmin is that it rarely appears to be very helpful in integrating with 3rd parties.  It always feel like such integration is allowed reluctantly. However, it is what it is so lets take a look at how I have got it to work for me.


Garmin Power Course v Garmin Workout

Before getting into the detail it is worth thinking about what data files would be helpful to appear on the Garmin. For me it is the following:

  1. Interval Target Power
  2. Current Power (3s average)
  3. Average Power for the Interval
  4. Interval distance remaining
  5. Interval number
  6. Cadence
  7. Heart Rate
  8. Time or Av Speed (I don’t always use these)

These are the two main options from the file download menu above that are worth thinking about.  Lots of detail on all of this can be found on the very helpful Best Bike Split support pages.


Garmin Power Course

This utilises the course functionality on the Garmin and works by GPS co-ordinates triggering the new interval when you arrive at the relevant point.  When you reach this point the Target Power flashes up onto the Garmin and the new interval distance is reset in the ‘Course Point Distance’ data field.  The main problem with this option is that, at the time of writing, I am not aware of a data field for the target power.  This means that you have to catch the alert when you start the interval.  Frankly I found this dangerous in the first few times I tried it as you spend too much time looking at the screen.

I am aware that Best Bike Slit are developing a Connect IQ app that will resolve this but it would not be all that hard for Garmin to give us that field I am sure.

Let’s explore my workaround.


Garmin Workout

Using the Garmin Workout download from Best Bike Split, I can create the following race screen.


Race Screen using Garmin Workout

Helpfully, the Garmin auto-laps each interval/workout step so “Lap Pwr” will give us the Average Power for the Interval we need. “Dist. to go” gives a countdown in distance to the next interval.  Workout steps shows the number of intervals and how far into the race we are.  I find this very useful from a mental point of view.  A key piece of advice when using this is to have an awareness of both where the tougher intervals are going to be and of any longer intervals. A 2km interval at the end of a race can be tough to eat with in your brain if you are not expecting it.

Overall it works pretty well as long as you remember to start your Garmin at the start line.


Getting the Workout File into the Garmin

One might be tempted to think that this would be as simple as the interface you have in Ride with GPS whereby you write the file to Garmin. But no nonny no no. This, my friends, is most definitely not simples.  Here is what you have to do (for a 520):

  1. Download the Garmin Workout file from Best Bike Split to your computer.
  2. Connect your Garmin
  3. Locate the “New Files’ Folder within the Garmin file directory
  4. Copy your Garmin Workout (.FIT) file there
  5. Eject your Garmin
  6. Check the workout has been loaded (in Menu – Training – Workouts)
  7. Load the workout on race day.


I have a couple of  observations here:

  1. It only allows you to have one race plan loaded in at a time. If you try to add another one, then the first one is over-written. I don’t know why.
  2. It takes more time to get the intervals onto the Garmin than it does to plan the race.  The biggest issue with this is that you would ideally want to update the race plan to reflect the most accurate weather forecast on race morning.  However, I would not be going through this palaver at 5am whilst eating my Ambrosia rice pudding. No way Jose.


Race Day

It is pretty easy to load the workout from (Menu – Training – Workouts) prior to the race.  The image below gives you an example of what you will see in the race (note – this example is obviously not from an actual race even the relatively  low power and HR)

Best Bike Split Race Screen

Race screen in action


Best Bike Split have recently announced a pretty cool integration with the Wahoo Elemnt which will cut out a lot of this manual labour. However, once the workout file is in the Garmin, it works pretty well.


Best Bike Split verses Reality

So now we know how to create the race intervals and how dd I do?

  • Time: 25.33 v 26:00.
  • Average power: 332 v 325 Watts
  • NP: 348 v 340 Watts


An analysis of the intervals (kindly recorded as auto laps by the Garmin) can be seen below.

Best Bike Split Plan V Actual

Race Plan V Actual

I was delighted with this.  I paced the race as per the plan and managed to squeeze a few more beans out at various times resulting in a course record.  I remember deciding to push a bit harder than the plan on the hills as I was feeling very good.  I also remember just trying to cling on for dear life on the return leg.  Here Best Bike Split was brilliant as I could just focus on trying to hit the interval numbers rather than worrying about anything else.

There is the odd small discrepancy here and there (e.g. overall course distance) but the plan is mostly spot on.

The Strava Activity also makes for happy reading.

Best Bike Split - Strava Summary

Strava Summary


Record Breaker

I used Best Bike Split to full effect one weekend in September to break the all time club records for 10 and 25 miles.

Saturday 10 September

Tonbridge Bypass (Course Q10/19):

  • Predicted Time v Actual: 19:55 v 19:40
  • Predicted Av Power V Actual: 330 Watts v 329 Watts


The race went very much to plan under ideal conditions.

Sunday 11 September

Port Talbot (Course R25/3L):

  • Predicted Time v Actual: 49:15 v 51:19
  • Predicted Av Power V Actual: 310 Watts v 307 Watts


This race did not go to plan at all.  The weather turned during the morning and ended up being a headwind in the wrong direction.  I also was not as disciplined as I should have been in sticking to the race plan early on and went too hard at the start.  This was primarily driven out of a desire to break the 50 minute mark.  I was also feeling pretty fatigued after the 10 mile efforts on the Saturday.  However, I do have a few observations:

  1. Best Bike Split really helped again when things were very tough towards the end of the race.  Again, I could simply focus on trying to get as close to the race intervals as possible until the suffering was over.
  2. The conditions (or fatigue from a previous days record breaking ’10’) did not prevent Marcin Bialoblocki smashing the competition record for 25 miles


I also reckon that the Wahoo Elemnt would have helped out here as it would have been pretty easy to update the race plan during the warm up. I am looking forward to reviewing how this works in practice along with the Kickr simulations in the future.


Best Bike Split is such a great tool that it does feel like cheating. It goes with our saying that you still have to deliver the power numbers and you have to hold position and generally do all of the good stuff that you need to do to be a successful tester.  However, I believe that for the club TT rider, Best Bike Split can help you take a huge chuck of time off your PBs.

I think we will see some great features introduced in relation to post ride analysis and the Wahoo integration is brilliant.

On a personal level I am looking forward to seeing how Best Bike Split can help me achieve some new goals for the coming season.

Don’t forget, to get your discount of 25% off Best Bike Split Premium simply sign up to my email list. If you are already signed up then you will have already received the discount code over email.

As ever, thank you for reading and let me know what you think in the comments.


  1. Bill_B

    Great article Rob, I’ve been experimenting with BSS over the Winter & agree that this is a great tool despite some of the third party interface issues. Logic applies to the modeled calculations so I will attempt to calibrate my setups to match the results before race season starts. My biggest concern is setting up the Garmin to provide me with a reliable means of monitoring progress during a TT (and leaving it to do it’s job). I want to press the start button and take the occasional glance and not waste energy trying to get the system to work. That’s technology though and your notes have helped a lot.

    • Rob Stephenson

      Hi Bill and thanks for the comment. I am glad my article has helped. The Workout option on the Garmin is pretty good once you have got the race plan in there and I like the fact that it does an auto lap for each step so you can compare actual with plan pretty easily afterwards.

  2. almost as slow as my garmin

    hi, this sounds like a great feature and your write up about it is great. I’ve created a course for my next TT but am really struggling to get it onto my Garmin 520. It keeps telling me invalid course! Have you ran into that at all? Do you look for the file in “courses” or “workouts? thanks

    • Rob Stephenson

      Hi Julie,

      Thanks for reading and apologies for the delay in responding.

      I have not seen the message that you mention but you should load the file in “workouts”. It has always worked fine for me that way..



  3. Adam Dennis

    Thanks for the article Rob, I have been testing out the different setting on my Garmin and after a couple of “B” races, got it spot on for my “A” race. With my power plan setup I was expecting a time of 5hr:45 (74%) effort on the Challenge Roth 112 mile bike section. As the roads were even better than than expected I came in at 5hr:32. Even better was the pacing, both 84km laps came in within 5 seconds of each other. 2:37:46 & 2:37:41

    • Rob Stephenson

      Brilliant stuff Adam – thanks for sharing and really pleased that it is working for you..


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