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Acceptable power loss

Posted: Fri May 23, 2014 2:47 am
by toolonglegs
Quick question... What would be an acceptable loss of FTP power in TT position?. Talking proper set up TT bike ( not just clip ons on a road bike ).
I think my position needs some tweaking as power is fair bit down on what I can hold on the road bike. Probably about 7 or 8 % down. The position seems pretty fast, but if I could modify my position a bit and gain another 30w from the legs it wouldn't hurt ( well it will hurt but you know what I mean ).
Or maybe I just need to spend more time training in this position ( which is comfortable enough ). Only spent about 20 hours on this bike so far.
Anyone got any comparisons?

Re: Acceptable power loss

Posted: Fri May 23, 2014 10:07 am
by Alex Simmons/RST
Tricky.

Really you want highest W/m^2 (i.e. speed), so if you have anyway of field testing your aero drag...

I didn't lose any power on my TT bike. Most of my TT clients over the years didn't lose much either. Occasionally some would be down 5%. 10% would be a lot IMO.

Re: Acceptable power loss

Posted: Fri May 23, 2014 3:53 pm
by toolonglegs
Thanks Alex, aim to get inside the 5% range then! . I have only got one TT to go off for now but I was 10% down on best efforts in that, but it was the 3rd stage of a 4 stage weekend and a course not really suited to my physique!.
I don't think I am too far off and probably just need to train the position a fair bit more ... and myself too!.

Re: Acceptable power loss

Posted: Fri May 23, 2014 4:15 pm
by Le Mong
Adaptation should help. How long have you spent on it pushing hard?

Re: Acceptable power loss

Posted: Fri May 23, 2014 4:40 pm
by toolonglegs
Not long, only had the frame for a month... definitely need more time on it.
I notice I struggle to maintain good power on the flatter / slightly downhill sections... I don't spin long cranks all that well obviously!.

Re: Acceptable power loss

Posted: Fri May 23, 2014 5:11 pm
by Alex Simmons/RST
Build up some quality MIET time on TT bike, but make sure position is right. Go from 30 minutes up to 3 hour/week total if your loads are high enough to cope.

Re: Acceptable power loss

Posted: Fri May 23, 2014 5:22 pm
by toolonglegs
Will do ... feel it a bit today in the front of my thighs so even though position is comfortable it will take time to get used to.
Not going to stress over it too much, going to be away from home much of June through to early September with only a road bike and mountains to ride. Not ideal TT training for September, but I am aiming to improve my aerodynamic drag by huge amounts in the next 3 months :wink: .

Re: Acceptable power loss

Posted: Sat May 24, 2014 3:47 pm
by ikm
I used to loose about 8% or so in my TT position, seems to have improved with spending more time on the TT bike though.

Re: Acceptable power loss

Posted: Mon May 26, 2014 10:11 am
by thearthurdog
It's hard to say because I feel like it varies depending on terrain. I think I lose a little more on proper hills than on the flat. If I had to put an 'average difference in power at the same RPE' I reckon I would say about 5%. I 'feel' like 380w on my road bike 'feels like' 360 w on my TT bike. I have no idea why I have just used the word 'feel' so much.

Re: Acceptable power loss

Posted: Mon May 26, 2014 10:13 am
by thearthurdog
toolonglegs wrote:I notice I struggle to maintain good power on the flatter / slightly downhill sections...


I'm exactly the same (on long downhills) and it frustrates me no end. If I could TT all day on a very slight uphill I would be a happy man.

Re: Acceptable power loss

Posted: Mon May 26, 2014 3:54 pm
by toolonglegs
Yeah the slight up hills are perfect... can hold FTP power perfectly plus some!. Even a headwind is fine. But the really fast sections I find I can't hold the power, maybe a combination of 180 cranks, low position and lack of flexibility etc... can't spin fluidly, just prefer a slight grind... if you know what I mean :wink:

Re: Acceptable power loss

Posted: Tue May 27, 2014 3:42 am
by toolonglegs
Maybe a candidate for rotor cranks!

Re: Acceptable power loss

Posted: Tue May 27, 2014 8:37 am
by Le Mong
172.5 cranks would be better than throwing money at bent rings. Been there done that, all it did was mask issues and make me grind big gears rather than spin at 120+ and hammered my knees.

Re: Acceptable power loss

Posted: Tue May 27, 2014 10:53 am
by thearthurdog
120+ ? Why so high ?

Re: Acceptable power loss

Posted: Tue May 27, 2014 12:54 pm
by Le Mong
Because I like to spin. 100-110 is my comfort zone and can comfortably spin up to 145+ on the road when needed.

I could never spin past about 110 on Q rings as I'd just start to Bob and become uncomfortable.

Acceptable power loss

Posted: Tue May 27, 2014 3:25 pm
by toolonglegs
I spin up to 120-130 in crits... But I prefer pushing a big gear. 172.5 cranks... Have them on my winter bike, they don't work for me, I can handle 175's on my CX bike or when I want a compact to go climbing, but when I put the 180's on I definitely feel better. In a sprint max power drops off a tiny bit but sprinting for a long time is easier. On the road bike I think 177.5 might be a good compromise, but on the TT the longer ones "feel" good as someone says :lol: .
I had many moons ago a set of Rotor Power Cranks ... They had a cam set up and actually accelerated the crank through the 12 o'clock position... They were heavy and had too many moving parts.
If I could find a cheap set of 180 Oval cranks I would give them ago.

Re: Acceptable power loss

Posted: Fri May 30, 2014 6:49 am
by thearthurdog
My coach and I have 'stumbled' on a big thing just yesterday in terms of power loss in position (can't believe we never realized this). I do a pretty solid core workout three times per week and have done this since September last year. Coming back into the sport after a 12 year break I had some major core issues which are now being addressed. I still have some way to go but the improvement is making a big difference. I'm in a fairly heavy phase of TT training at the moment, and we have discovered that the impact my core session (which is a bloody hard little session) is having on A - my ability to stay in position and B - power loss in position, is significant. The obvious conclusion being that the fatigue I am creating in my core is having a BIG impact if I ride the TT bike the same day or the next morning. This has just meant a subtle shift in when my core sessions are done. We stumbled across this last week when for various reasons I did a TT session after a three day period with no core work and my comfort level and power numbers were up up up. Just thought I would mention it...

Re: Acceptable power loss

Posted: Fri May 30, 2014 3:04 pm
by toolonglegs
Makes sense... A hard work out off the bike will affect your efforts on it.
I don't do much in the way off core workouts... Mainly stretching. I'm going to try and figure out why I can hold much better power on a gentle climb or into the wind... But not today, felt great in yesterday's race... But hip flexors have ached all night long.
Slow today!.

Re: Acceptable power loss

Posted: Fri May 30, 2014 5:13 pm
by foo on patrol
X2 to what TLL has said. :wink:

Foo

Re: Acceptable power loss

Posted: Fri May 30, 2014 5:20 pm
by Alex Simmons/RST
Just a link on this core issue, since I've written about it elsewhere, no point repeating myself:
http://www.bikeradar.com/forums/viewtop ... #p18876419

Re: Acceptable power loss

Posted: Fri May 30, 2014 6:37 pm
by thearthurdog
Thanks Alex. I'm curious to see what impact the changes to the timing of my core workout has on my other sessions. Perhaps none? We will see I guess.

Re: Acceptable power loss

Posted: Fri Jun 06, 2014 7:21 pm
by MDL
Authur - you don't need to improve anymore.

But on the cadence side of things. I see alot more people are starting to run alot higher cadence in the TT's 100-110 range. Noticed this with the NRS/mas A/Elite A riders at the Battle on the Border TT and the Ippy TT

MDL

Re: Acceptable power loss

Posted: Fri Oct 03, 2014 6:24 am
by toolonglegs
This still seems to be an issue for me!. Over winter i think I will start from scratch on my position.

Re: Acceptable power loss

Posted: Fri Oct 03, 2014 7:10 am
by CKinnard
In my experimenting, reduced bodyfat % makes a massive difference. It seems to reduce inhibition of iliopsoas the main hip flexor, and keeps the abdomen and diaphragm more comfortable. If your feeling your diaphragm isn't descending comfortably, that can potentially raise intrathoracic pressure with inspiration, and possibly impede venous return to the right atrium....thus compromising cardiac output.

Re: Acceptable power loss

Posted: Fri Oct 03, 2014 9:23 am
by Strawburger
Just completed the nsw and national masters ITT and found that my legs were the limitations. On rough calcs I had a 20% loss of power with my position on the TT bike, but a 10% gain in time.

My legs would burn but the lungs and heart were comfortable. More time on the TT bike perhaps... I'd love to pull 5% losses or less, need all the watts I can get!