"harder" to ride at power, Tri bike or road bike?

scott dinhofer

I have always subscribed to "watts are watts"

I had been doing the OS on my road bike on a trainer and hitting numbers on all WKOs. a few weeks ago I scored a ten watt bump to all time high. two weeks ago I switched to my tri bike. I started to lengthen my Saturday WKO from 90minutes to 120 to 135.

I figured the extra fatigue I have been feeling was from those longer Saturday rides. I am now generally having a lot of trouble holding power at the newer higher numbers. I realized while struggling through tonight's WKO that my gearing has me searching for a gear in between the two i am forced to ride, one at cadence of 95 and the other at 84, damn, i want 90! but there it was, duh i switched bikes!

 as for positioning, i was riding the road bike on the hoods and i am riding the tri bike on the bullhorns, on a P5 that is much lower than where it was on my P2, but still not in the aero bars in Z4. IN Z3 I am in the aero bars much of the time.

thoughts on dialing down my FTP based on these observations? sadly that would erase any gains i had thus far. I am thinking of putting the road bike back on for the next ride to test the issue.

jaleslie

When I saw the title of your post, I thought I'd be able to help/comment.  But, after reading it....I'm puzzled too!  Only thing I can think of is that your seat tube is more upright on the TT bike c/w the road bike.  Hard to believe it makes that much difference if you're sitting up on the bullhorns for the Z4 intervals and such, though.  Sounds like you have different cassettes on the bikes?  Again, hard to believe that explains it, even if you are sort of between gears in Z4 on TT bike currently.  

I will keep an eye on this thread....maybe I'll learn something too!

 

Al Truscott

In general:

• The bullhorns on a TT bike provides body angles similar to the drops (not the hoods) on a road bike.
• The lower you are, and the more directly your hips are over the cranks, lower your power will be compared to a standard road bike position. So TT FTP will usually be lower than road bike FTP
• It's a good idea to have an FTP specific for what you are doing: trainer vs open road, TT vs road bike, OS training vs race prep. If you want to bring in as many muscles as possible, do your trainer rides with a road bike, on the hoods. If you want to mimic racing and get tuned into aero position, then do the wkos on TT on the bars. Or any other combo which you prefer. But either be consistent, or be willing to fiddle around with your FTP as the situation requires - you will need a different FTP for each of those.

What do I do? I use my TT bike on the trainer, and have a trainer FTP. Come April or so, I get myself a TT FTP on the road, and use that as I tune in for long course racing.

Coach Patrick

x2 what Al said. Switching bikes is just like swapping powermeters...you are still getting power but in a PM switch case, you'd _know_ you needed to retest. It's the best way to go...

scott dinhofer

@ Al - how much would you dial back the FTP as a guideline prior to being able to work a test in to it?

@ Patrick - this makes it hard to feel like my FTP is improving!!!! good news is that outdoors FTP is higher, right???!!! :-)

John Withrow

@Scott- you're overthinking it buddy... The position is a little different so you recruit slightly different muscles. Dial it back to 95% for your next workout and see if you can hit those. If so, move it up to 97% for the next one and if not try 93% for the next one instead. Lather, rinse, repeat. In like 5 workouts you'll be humming along at your old "new" FTP. Just stay on that P5 and you will acclimate (don't go back to the roadie to do an experiment). It doesn't matter. You are doing the work, you are getting stronger. And the reality is, even if you are putting out a few less watts, you will still be faster on that P5 which is the whole point anyways. I love chasing numbers more than the next guy, but just let it happen. And also make sure you are properly resting/recovering and properly fueling yourself and sleeping properly.

Al Truscott

Posted By Scott Dinhofer on 26 Mar 2014 04:03 PM


@ Al - how much would you dial back the FTP as a guideline prior to being able to work a test in to it?  

SWAGing it … start with a 5% reduction from your new, road bike, trainer FTP (which probably gets you back close to your old FTP?) for your tri bike on the trainer. Go up or down from there depending on how easy/hard it is to hit the target watts.

You may not have it this easy, but on the trainer, I am using Trainer Road with a CompuTrainer. In the middle of any interval, if I think I need more or less resistance, I just hit the + or - button to change by 1%, until I find the sweet spot. TR road lets you do that on the screen via the mouse. 

GMAN 19030

I use my road bike almost exclusively on my trainer. I use my tri bike almost exclusively outside.

I'm about 5% more powerful riding a road bike. I'm also about 5% more powerful outside. So it's a wash for me as my indoor road bike power is about the same as my outdoor tri bike power.

scott dinhofer

this is all really good info and frankly the true value of EN

@ JW: do you have shorter cranks on the P5? do you think it makes a difference? Long course? You really want to provide some afternoon entertainment, THANKS!

Al Truscott

Posted By Scott Dinhofer on 27 Mar 2014 11:56 AM


@ JW: do you have shorter cranks on the P5? do you think it makes a difference? Long course? You really want to provide some afternoon entertainment, THANKS!

Re: shorter cranks … I've gone from 172.5 >> 167.5 >> 165 over the past three years. I do not notice any change in my ability to generate power. What I do notice is I'm able to get my front end lower, since my knees don't meet my chest anymore. In fact, I was able to get TOO low, and had to move up one spacer (5 mm) to get back to an optimum position.

My conclusion is shorter cranks allow for a more aggressive and a bit more comfortable aero position, due to changes in where you can place the saddle, and dropping the front end. But I don;t have a faster cadence or more (or less) power.

William Jenks

Very short version: I agree with Al's last post. The laws of physics mean that something has to give, though...either a change in cadence, a change in gearing, or a change in applied linear force....assuming you are putting out the same power. For me, I suspect I just use very slightly different gearing than I otherwise might...but it's not noticeable.