Training set up question

[bex]

Hello there everyone
I have not bought an Ibike yet and I am still trying to decide which one to get (Aaron has been helping me no end with answers to my questions, thanks Aaron!!). It would be for me to help my wife perform better at triathlon.
Right now we have a bike set up for her that includes 700c wheels, compact 50/34 chainrings and 165 crank arms and a 12/27 cassette.
The bike is a little too small.
We have another bike but it has 650c wheels.
She completed a just about perfect IM Canada this year and the reason we deduce this is a negative split on the run section.
Now the question(s)
Can I use the ibike (sport, pro or aero) to determine if a change of bike/cranks/cassette/chainrings has a positive or negative effect on her bike performance
From the information obtained can I determine whether this will have a positive or negative effect on her run.
What information from the pro/sport/aero am I looking for.
How do I make use of the information when making changes to the bike set up.
After we have made appropriate changes, the unit will be used as a training tool but initially it is just for what I have described.
Thanks so very much for any input you can give me

Stephen

[lorduintah]

Just a thought -

If you have a trainer, you might be able to get some of this information on the drivetrain changes by seeing the average output and effect on HR over, say 20-40 minutes of busting a gut. Or you could run through the gears, check cadence and output v. speed, etc., once again observing ability to maintain some speed/power level.

She could then hop on a treadmill and see how she feels running after some of these options.

If you are scientifically inclined - you could even run a designed experiment and analyze a number of factors for what might be an optimal combination.

Tom Anderson

[nreimche]

This may help, I have observed that my wife and myself each have an optimal cadence. When my wife did a ramp test (starting from 80, or so, watts, then increasing power by 10 watts every minute and recording heart rate and power at that time) she actually had a higher heart rate at 90 watts then at 100 watts, because I shifted her into a harder gear. Her cadence was 100 rpm's at 90 watts, but at 100 watts (again w/ a lower heart rate at the end of the minute, then at 90 watts)) she was between 80 and 90 rpm's. I know this is only one aspect of the spectrum, but I hope it does help.

[bex]

Thanks Guys, that does help. The idea of devising a set of tests is appealing.
Would you think it would go something like this:
Set the original bike up and do a series of time trials on the trainer over the course of a week or so perhaps.
The bench mark would be perceived effort and heart rate (as I do not yet have the ibike) using the original bike as that was the race bike we used for IM Canada.
Then try a different gear and higher or lower cadence depending on that gear choice.
Then, same bike, different rear cassette
same bike different crank length.
Then switch bikes and repeat.
Does that sound about right?
One thing right off the bat, the loss of speed that we need to make up because of the wheel size reduction, if indeed we can make it up.

Steve

[racerfern]

I'm no expert at trainers since I just unwrapped mine yesterday, but I was amazed at how much more effort is required on a trainer just to stay moving. I think you should search the web for discussions about Perceived Effort and HeartRate drift on trainers. A powermeter on a trainer really does make sense.

[bex]

Can I deduce from your reply that heart rate drift might be a problem in figuring this out?
I can see how it might be, but perceived effort is perceived effort (isn't it?), regardless of set up. If it feels easier with one set up over another for the same distance covered but you cover the distance quicker then thats what we are looking for isn't it. Or (in my ignorance) am I being too simplistic about it.
Is it a lot more complicated than I think?

[namblor]

Don't you think perceived exertion and heart rate are a little too subjective for subtle adjustments like you propose, ie. compact v/s regular cranks? Wouldn't objective numbers taken off your trainer, or on the track with an iBike be a better solution? If you are really serious about what you propose, just buy the pro model, and get on with the testing.

[R Mc]

First: the crankset issue is sort of a red-herring: find the arms that work best (and 165 is probably too short unless she's 5'2" or something). Really, compact cranks are only necessary for extreme climbing situations, and unless the bike legs of these tris involve 10 mile passes, there's no need to have a 34x27 on the bike.

Second, the ibike pro or aero will give you the cdas for the two different bikes, as well as an indication of how much power she can sustain in a tt position. The tradeoff between those two numbers is your criterion for deciding which bike to choose.

[bex]

She is 5'3" so the 165 are just about right I think.
We used the Compact because of the mountains in IM Canada. But wondered, because of the idea of saving the legs for the run section, if we should continue with them. If too big gears are pushed for the bike section this will have a negative effect on the run, that was the reason for the post in the first place. Not necessarily to get a faster time on the bike but to ensure she has a balanced race.
I think the Ipro is the way to go.
Thanks for your input folks

Bex

[lorduintah]

I have found that the power readings, cadence and HR are very well controlled on a trainer. There is only one thing you are dealing with and that is the trainer's resistance.

That summarized, a trainer is not likely to help you change body position, bike geometry and things affecting aerodynamic resistance. You would have to do those on the road and an iAero with another Power meter would be the combination to work out that (without a wind tunnel and dynamometer around). It should allow you to get a good feel for some of the other options you are concerned with as far as bike set up.

It sounds like you are pretty serious about the competition and a biking coach - even one or two sessions might help you work out some of the details - still, having an iBike Pro or Aero for training in general sounds like part of your solution regardless of what path you take.

Tom

[coachboyd]

If you are going to set the unit up for triathlons, you want the fastest possible bike time without making yourself too tired for the run. This means to go fast without expending a lot of watts, which is what the iAero will be great at.

You can make sopme changes to the bike, coast for ten seconds and look at the snapshot cda. I would also advise finding a two mile section of flat road on a VERY calm day weather wise and making runs at specific wattage and mark down how much time it takes you to complete the two miles. If you have to take 4 or 5 hours getting your position dialed in, it's worth it!

Most of our energy (especially when going at speed) is overcoming air drag. The more aero you can get, the faster you can go and doing it with less watts. So, if you can find a way to keep the watts the same but drop a bunch of time from the bike portion, she will have the same run time and obviously be better off. This does require training in the new position to be comfortable and so you can put out the same amount of watts at the same comfort level.

For everybody's information, last year I put myself through a two day "boot camp" of aero testing. I managed to lower my cda on the iBike by .02, and that change alone got me almost thirty seconds faster on the monthly ten mile time trial that we do at Lowes Motor Speedway, and I put out the same amount of watts as the previous time trials.

[bex]

Thanks for your reply's and information therein, I really appreciate it.
I aero then.