Predicting IM Bike Split

ironmtngrl

In the power webinar EN bike execution guidance says, "if you expect to ride a bike split of X, look at this nifty Excel chart to determine a good TSS and IF to target."  My question is, how can I get a good prediction of what my IM bike split will be given the only thing that I know at this point, my FTP?  I've seen references to an EN chart, but haven't been able to find it.  Seems logical that you could give a decent guestimate for split based on FTP assuming the person is riding about 70%, and maybe  taking into account the general hilliness of the course.  I'm looking to use this as motivation.  I.e. "if I can just lift my FTP to X, then I can potentially ride sub-Y in my next IM!"

Ammendment: actually watts/Kg would probably be the better predictor, right?

Thanks!

Chris G

Chasing IM split times is usually a bad call.  However, you need some idea to figure out the "gears" for the ride.  You will have a much better idea of the split after doing the longer rides and RR's as the time for race gets closer.  See that you are racing LP this summer, you coming up in the first week in June?  Doing a RR on the course will give you a pretty good idea, or at least it should.  One thing you can be sure of is that you will have a lot of help in figuring it out as you get closer.

cwhyte

Posted By Beverly Richardson on 03 Jan 2011 03:30 PM

In the power webinar EN bike execution guidance says, "if you expect to ride a bike split of X, look at this nifty Excel chart to determine a good TSS and IF to target."  My question is, how can I get a good prediction of what my IM bike split will be given the only thing that I know at this point, my FTP?  I've seen references to an EN chart, but haven't been able to find it.  Seems logical that you could give a decent guestimate for split based on FTP assuming the person is riding about 70%, and maybe  taking into account the general hilliness of the course.  I'm looking to use this as motivation.  I.e. "if I can just lift my FTP to X, then I can potentially ride sub-Y in my next IM!"

Ammendment: actually watts/Kg would probably be the better predictor, right?

Thanks!

I believe the primary focus should be on gearing based on target IF. I believe the idea behind using predicted bike split and target TSS is just to give you another set of data to help fine tune your gear selection. If you really have no idea what your potential bike split might be on a given course, which many don't, then focusing on a target IF of .70 is a great place to start. If you can't hold that number easily on a long ride then readjust.

Thanks, Chris

mgraffeo

Beverly, i was in the same boat last year, and did exactly what Chris W suggested, which worked well for me. good luck!

Steve West

So to clarify, since I have no clue what my split will/could/should be, my race can be based on FTP (right now it is at 205). I would focus on keeping my power at
205 x 0.70 = 144w with some minor "gear" adjustmests for hills (from EN_Power_Racing_Calculator.xls)?

Or do I display IF on my Joule and focus on IF=0.70?

Scott Alexander

@Steve, I'd aim for the real-time watts of 144w.

Personally, having that .70 +/- staring at me in the face makes me want to stomp on the pedals to reach my target.

Matt Samojeden

Steve, With the Joule having access to so much info there are many ways to get it done.   My approach is to focus primarily on the realtime watts being displayed. My secondary number is the NP average which I try to keep at my gear 2 target watts. 

Now averages become hard to move over longer periods of time. So for an IM, I take 30 min intervals ( an hr would be fine) on the Joule so that I can make sure that my NP watts are not drifting significantly due to terrain or the later section of the race where the body tends to want to pull the power back a bit if left un attended.

Nemo Brauch

Beverly-it's really hard in January to come up with a "should vs could" time for an IM that you are doing in June. But by the time you are a few weeks out from that race, you'll have many many miles under your belt as well as 2 race rehearsals and you'll have a much better ability to estimate that number. So don't get too wrapped around figuring it all out now- you've got time.

 

PS- we get this question / comment every year during the OS.  It usually ends up being a bigger distraction than a motivator.  Just work the plans and get the biggest FTP you can get for yourself.  If you want to have a number to target, play in the "heads we win, tails you lose" game and let that be your motivation for now.

William Jenks

I think it's invaluable to have a current watts, both for under and overshooting...the latter being potentially more dangerous, especially uphills. But, like Matt, I find the average also very helpful, and I do exactly the same thing - hit the "lap" every 30 minutes to reset the average.

Current IF and current power are, of course, equivalent...but the former is a bit compressed in scale, so you might find it easier to see small differences in power using the latter.

Steve West

Posted By Matt Samojeden on 04 Jan 2011 08:47 AM

Steve, With the Joule having access to so much info there are many ways to get it done.   My approach is to focus primarily on the realtime watts being displayed. My secondary number is the NP average which I try to keep at my gear 2 target watts. 

Now averages become hard to move over longer periods of time. So for an IM, I take 30 min intervals ( an hr would be fine) on the Joule so that I can make sure that my NP watts are not drifting significantly due to terrain or the later section of the race where the body tends to want to pull the power back a bit if left un attended.

 

@ Beverly - I didn't mean to hyjack your thread, but I was wondering the same thing.  Looks like we got some great answers here.

@ Matt - your answer made things crystal clear and the idea of using intervals to refocus intensity is fantastic..... so simple yet so powerful.

Thanks to William, Nemo and Scott too for your perspectives.  Seems like everyone is on one page.....

ironmtngrl

Cool - thanks all! I won't focus on this now, just work on the FTP watts. I will definitely try to get out to the LP camp and get a preview of the bike course. I like the idea of the 30 minute lap button to track averages as well.