Yet Another Cycling Forum

General Category => Freewheeling => Racing => Topic started by: Aleksdad1 on January 29, 2018, 03:05:20 pm

Title: Wattage Required to do 40k for one hour.
Post by: Aleksdad1 on January 29, 2018, 03:05:20 pm
I have just invested in a Wattbike Atom and would like to see what I can do with some proper training when it arrives in about two months. I have done many 40k p/hr + TT rides of up to 80k about 45 yrs ago but I would like to know if it is feasible to do so again even if only for 15k or 40k rides. Does anyone know how many watts I would need to achieve this again? I appreciate there are so many variables but think there must be a vague rule of thumb.
Title: Re: Wattage Required to do 40k for one hour.
Post by: simonp on January 29, 2018, 03:11:58 pm
http://forums.roadbikereview.com/racing-training-nutrition-triathlons/average-power-do-sub-1hr-40k-time-trial-326408.html

I guessed 250w for a TT bike, seems right sort of ball-park if this thread is to be believed.

Tests that estimate your FTP using shorter efforts will over-estimate your hour power, so add 10-15% margin to that.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Samuel D on January 29, 2018, 03:12:16 pm
Very roughly 250 watts with aerobars. You would have needed more power 45 years ago without those.
Title: Re: Wattage Required to do 40k for one hour.
Post by: hubner on January 29, 2018, 03:14:21 pm
40kph, 40km. But you do need to type more letters though.
Title: Re: Wattage Required to do 40k for one hour.
Post by: toontra on January 29, 2018, 03:14:38 pm
I was going to say about 260-270w.  That's from personal experience on a Wattbike-type trainer, but I wouldn't be able to maintain that for a whole hour, sadly.
Title: Re: Wattage Required to do 40k for one hour.
Post by: DuncanM on January 29, 2018, 03:24:06 pm
I don't know what wattage is required for a given speed - the variables of bike/position/course are so large as to give a large margin for error anyway.
One thing to be aware of is that you will need a decent size fan (or 2) if you want to run the same power as you do outside for any duration. Lack of cooling can seriously restrict your power.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Aleksdad1 on January 29, 2018, 03:38:30 pm
Many thanks for these replies. I can see I will have to do a bit of work. I have started doing 5 x 3 min intervals at the gym and am doing over 200 watts going over 300 for the last minute but know I could not hope to maintain this for one hour. I do not have a TT bike and do not intend to purchase one until I see that my goals are achievable so will content myself with adding aerobars to a road bike after a few rides without them to give a base level.
Title: Re: Wattage Required to do 40k for one hour.
Post by: toontra on January 29, 2018, 03:56:16 pm
That sounds like a sensible plan.  I don't have a power meter on any of my rod bikes but find the gym trainer very useful for monitoring wattage as there are no variables so you can directly compare performances over time (particularly if I can nab the same bike each session as they do vary a little even if the same model/age/etc).

Having a Wattbike at home sounds great.  Good luck!
Title: Re: Wattage Required to do 40k for one hour.
Post by: phantasmagoriana on January 29, 2018, 04:34:12 pm
Indoors on a Wattbike or similar you probably wouldn't need so many watts. The data for the last hour-long spin class I did shows 215W average and 42kph average speed (though that was intervals and stuff rather than just trying to maintain the same power for an hour). Wouldn't get anywhere near that average speed for the same power outside, though. :'(
Title: Re: Wattage Required to do 40k for one hour.
Post by: simonp on January 29, 2018, 04:35:21 pm
I'll be interested in hearing how you get on with the Atom.
Title: Re: Wattage Required to do 40k for one hour.
Post by: toontra on January 29, 2018, 04:59:15 pm
The data for the last hour-long spin class I did shows 215W average and 42kph average speed (though that was intervals and stuff rather than just trying to maintain the same power for an hour).

Those figures don't add up.  You can't generate 42kph (av.) at 215w (av.) on any trainer or spin bike I've ever used.  The better bikes I've been using are pretty accurate and 215w (av.) will give you 33kph (av.) tops.  Much different than that and your bike's not calibrated correctly.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Samuel D on January 29, 2018, 05:02:27 pm
The concept of speed on a stationary contraption is too ridiculous to consider in the first place.
Title: Re: Wattage Required to do 40k for one hour.
Post by: toontra on January 29, 2018, 05:04:23 pm
The concept of speed on a stationary contraption is too ridiculous to consider in the first place.

True, but wattage can be very accurately tracked.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Samuel D on January 29, 2018, 05:08:13 pm
It can, and that seems adequate to gauge performance on these machines without adding an imaginary speed.

Zwift takes the imaginary speed a bit further, of course. There is a market for imagined bicycle rides. I’d rather just do them. Luckily I live in a part of the world that allows cycling all year around.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Giropaul on January 29, 2018, 06:00:38 pm
In general, my experience is that 40 km in 1 hour needs an average in the low 200’s Watts on a Wattbike.

A Wattbike is probably one of the few calibrated machines, other devices use algorithms etc.

However, in the real world watts/kg is what really matters. A 100kg rider could ride 40 km on a Wattbike, but would be slower than a 60 kg rider.  In hilly country the gap increases of course.
Title: Re: Wattage Required to do 40k for one hour.
Post by: phantasmagoriana on January 29, 2018, 06:26:06 pm
In general, my experience is that 40 km in 1 hour needs an average in the low 200’s Watts on a Wattbike.


That tallies with my experience - I'm used to Matrix IC7s rather than Wattbikes, but they're also power meter-equipped. It also tallies with data I have from using Zwift (using a Stages power meter).

The concept of speed on a stationary contraption is too ridiculous to consider in the first place.

Of course. It's not something I've ever even looked at before before this thread prompted me to look at past data. (I'd also love it if Strava could discount indoor "miles" automatically, but that's veering off-topic!)
Title: Re: Wattage Required to do 40k for one hour.
Post by: Giropaul on January 29, 2018, 07:18:55 pm
It can, and that seems adequate to gauge performance on these machines without adding an imaginary speed.


As a Wattbike user and instructor I agree. Power and pulse are the key parameters.

However, sometimes someone comes up with a charity “ how far can you go in an hour?” sort of event - like I got talked into last Saturday!
Title: Re: Wattage Required to do 40k for one hour.
Post by: Greenbank on January 29, 2018, 07:36:22 pm
I do not have a TT bike and do not intend to purchase one until I see that my goals are achievable so will content myself with adding aerobars to a road bike after a few rides without them to give a base level.

You may also find that you can generate the required power on a Wattbike as it has a much more relaxed postion, but when you move to a road bike with aerobars you may find you're unable to generate that same power in a different position.

TT-ing is a lot about adapting positions on the bike such that the aerodynamic gain is more than the subsequent loss of power it causes.

That being said, there's nothing stopping you building up your power with some structured training until you think you are getting close, and then giving it a go.
Title: Re: Wattage Required to do 40k for one hour.
Post by: dim on January 29, 2018, 07:37:54 pm
I'd love to know how many Watts Chris Froome produces ...

this was his weekend ride in South Africa:

https://www.strava.com/activities/1379317668 (https://www.strava.com/activities/1379317668)

271.65km .... 3,485m .... and his average speed was 44.8km/h
Title: Re: Wattage Required to do 40k for one hour.
Post by: Samuel D on January 29, 2018, 07:45:56 pm
I’m curious despite myself how these machines estimate speed from power. Do you give them your weight and they simply read a speed off a curve in firmware for the applicable weight?

I have noticed on the road that I am more aerodynamic than almost all others (talking road bikes). On the other hand, I’m light and don’t have a lot of power. This combination reveals that speed estimates from weight and power can be inaccurate, because bigger guys often out-climb me and I often outrun them on the flat despite having nothing like their power output.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Greenbank on January 29, 2018, 07:48:59 pm
I'd love to know how many Watts Chris Froome produces ...

Reasonably public knowledge.

http://www.cyclist.co.uk/news/691/chris-froome-s-numbers-what-do-they-really-mean

An FTP of 419W (although he probably wouldn't be able to put out 419W for an hour in a TT position for the reasons I posted above.)
Title: Re: Wattage Required to do 40k for one hour.
Post by: zigzag on January 29, 2018, 07:49:23 pm
for what it's worth, checked the stats of my first 40km of the 24hr tt (the only proper tt i've done so far, on a tt bike):

speed - 36.2kph
power - 178w
heart rate - 147bpm
cadence - 89rpm
temp - 29deg

i reckon 230w should be enough to ride 40km in 1hr.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Greenbank on January 29, 2018, 07:59:07 pm
for what it's worth, checked the stats of my first 40km of the 24hr tt (the only proper tt i've done so far, on a tt bike):

And to compare what weight (88kg, it wasn't a pan-flat TT) and a non-aero position do, here's my stats for the first 40km of that very same TT (on a non-TT bike but with aerobars but I hadn't trained on the aerobars so I wasn't able to stay in them for long periods):-

speed: 28.0kph
power: 166W
HR: 154bpm
cadence: 88rpm
Title: Re: Wattage Required to do 40k for one hour.
Post by: dim on January 29, 2018, 08:14:50 pm
for what it's worth, checked the stats of my first 40km of the 24hr tt (the only proper tt i've done so far, on a tt bike):

speed - 36.2kph
power - 178w
heart rate - 147bpm
cadence - 89rpm
temp - 29deg

i reckon 230w should be enough to ride 40km in 1hr.

and which way was the wind blowing, and how strong was it?
Title: Re: Wattage Required to do 40k for one hour.
Post by: zigzag on January 29, 2018, 08:19:05 pm
the wind wasn't much of a factor that day, iirc
Title: Re: Wattage Required to do 40k for one hour.
Post by: Greenbank on January 29, 2018, 10:01:16 pm
and which way was the wind blowing, and how strong was it?

3kph and from the North according to my Garmin Connect activity (which was probably what the weather was at the start of the activity). The first 40km were due East for about 7km (quite sheltered), then S/SES for the remainder.

I can't remember any noticeable wind during any of it.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Karla on January 29, 2018, 10:35:50 pm
My last two 25 mile TTs were 233W for 57:06 and 234W for 57:04.  Both were last spring, neither were ideal weather wind-wise, both were on a TT bike with full pointy hat get-up and both were on the A168/A19 north of Topcliffe.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Frank9755 on January 31, 2018, 08:15:55 pm
That's very similar to my last 25, 230w for 57:28.
I would have guessed that you would have put out more power than that!
Title: Re: Wattage Required to do 40k for one hour.
Post by: rob on January 31, 2018, 09:34:48 pm
Interesting.   Did a long 53 last year but it was a fast day on the E2.

At some point I’ll find out what my power numbers are.
Title: Re: Wattage Required to do 40k for one hour.
Post by: LMT on February 03, 2018, 10:10:56 pm
Depends on the bike, for me on my recumbent it's a little under 200 watts - Z2. ;D

Having just checked a ride, pre LEL training I done a 80.52km ride with 541m of elevation in 2:17.31. AP was 180w and NP was 193w.
Title: Re: Wattage Required to do 40k for one hour.
Post by: rogerzilla on February 04, 2018, 10:06:02 am
These all sound like very low figures, which surprises me because I'd have thought watt-measuring components would be calibrated on the generous side.  However, you can get artificially low figures depending on the way it's done, e.g. a hub will give lower power measurements because of drivetrain losses, and the meters that only measure from the left crank will give spuriously low results if you're very right-legged.  Personally, at my age, I just don't want to know.  If I can get up hills with the first few in the group, that's fine by me  :)
Title: Re: Wattage Required to do 40k for one hour.
Post by: rob on February 04, 2018, 02:30:24 pm
I’ve seen the 250w estimate a few times on the TT forum so it sounds about right.

Aero tech has moved on so much that there’s riders cracking the hour at much lower wattages.  I also don’t measure my power on the bike and I haven’t done a ramp test for a few years.   I know I was faster last year and that’s all that really bothers me.
Title: Re: Wattage Required to do 40k for one hour.
Post by: LEE on February 04, 2018, 07:48:10 pm
I'd guess at 250-280 Watts, if you are aero.

My FTP is about 280.  I never rode a TT bike but I know it would most likely reduce my ability to produce 280W.

I can do 30k in an hour on a "normal" bike.  I have no idea what difference to my speed a full aero setup would make.  I don't want to try because I would seem forever slow afterwards.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Karla on February 04, 2018, 08:14:05 pm
FYI my figures come from a spider-based unit.
Title: Re: Wattage Required to do 40k for one hour.
Post by: simonp on February 04, 2018, 08:25:57 pm
That sounds cruel.
Title: Re: Wattage Required to do 40k for one hour.
Post by: IanDG on February 05, 2018, 07:15:48 am
Just 'did it' back in the day no idea what wattage. But then I'm an old fart! It's great how the science of sport has developed. Something I was very interested in back in the 70s/80s ;)
Title: Re: Wattage Required to do 40k for one hour.
Post by: DuncanM on February 05, 2018, 02:07:04 pm
This topic made me think about the Watts I can produce (FTP 222 at the moment, but going up) and how fast it will get me.
For those who are/have been actively time trialling - how did you go about "getting aero"? I want to try TTing this year (only 10s and maybe a 25 if it goes well), but I'll be restricted to riding my road bike https://www.cube.eu/uk/2017/road-triathlon/attain/cube-attain-gtc-pro-disc-greynflashgreen-2017/ (https://www.cube.eu/uk/2017/road-triathlon/attain/cube-attain-gtc-pro-disc-greynflashgreen-2017/). Is it worth getting some cheapass aero bars, or just focusing on riding in the drops (or aero laid out on the hoods) - how much difference will it make?
Title: Re: Wattage Required to do 40k for one hour.
Post by: LittleWheelsandBig on February 05, 2018, 02:20:12 pm
Aerobars are worth getting. I stopped racing seriously nearly a quarter century ago but when aerobars came in, they were noticeably quicker than when on the drops (with all other equipment the same).
Title: Re: Wattage Required to do 40k for one hour.
Post by: sib on February 05, 2018, 02:26:21 pm
Aero bars definitely worth it - also skinsuit and aero helmet if you want maximum advantage.
As to how to find the best position either pay for it e.g. aerocoach or use your powermeter to do some diy testing.
Title: Re: Wattage Required to do 40k for one hour.
Post by: DuncanM on February 05, 2018, 02:42:01 pm
I don't think it's worth paying to find my "best position" on what is a flawed TT bike (seat angle laid back, long head tube, disc brakes). I don't have a budget for a TT bike though (not even a cheap secondhand one).
Title: Re: Wattage Required to do 40k for one hour.
Post by: sib on February 05, 2018, 02:44:23 pm
I don't think it's worth paying to find my "best position" on what is a flawed TT bike (seat angle laid back, long head tube, disc brakes). I don't have a budget for a TT bike though (not even a cheap secondhand one).

Do you have a power meter or is your wattage derived from the turbo ?
Title: Re: Wattage Required to do 40k for one hour.
Post by: LittleWheelsandBig on February 05, 2018, 02:46:12 pm
Do roll-down tests. If you ensure no wind, constant temperature and consistent road surfaces, they are quite repeatable.
Title: Re: Wattage Required to do 40k for one hour.
Post by: DuncanM on February 05, 2018, 03:10:11 pm
I don't think it's worth paying to find my "best position" on what is a flawed TT bike (seat angle laid back, long head tube, disc brakes). I don't have a budget for a TT bike though (not even a cheap secondhand one).

Do you have a power meter or is your wattage derived from the turbo ?
I have P1 pedals. I guess for aero tests I would need to find a flat bit of road where I ride at a given wattage for a mile or something and see what the speed is. And then repeat and repeat. Rolldowns would be an alternative if I can find the right sort of hill...
Title: Re: Wattage Required to do 40k for one hour.
Post by: sib on February 05, 2018, 03:14:56 pm
Yes. Those are the simplest ways to test although you have to be wary of the impact of wind or traffic.
Title: Re: Wattage Required to do 40k for one hour.
Post by: Samuel D on February 05, 2018, 04:51:56 pm
I have P1 pedals. I guess for aero tests I would need to find a flat bit of road where I ride at a given wattage for a mile or something and see what the speed is. And then repeat and repeat. Rolldowns would be an alternative if I can find the right sort of hill...

You could do a lot better than that with Robert Chung’s virtual-elevation method, described here (http://anonymous.coward.free.fr/wattage/cda/indirect-cda.pdf) (PDF). Tiny differences in drag can be reliably detected with this imaginative technique. And since many cyclists and coaches use it, there are plenty of helpful descriptions of the process online. I think some training software packages automate many of the steps.
Title: Re: Wattage Required to do 40k for one hour.
Post by: zigzag on February 05, 2018, 04:53:41 pm
few simple modifications (inline seatpost with the saddle in forward position, -17deg stem with no spacers underneath and clip-on tribars) can make a road bike reasonably faster. going further - aero kit and wheels, although it gets more expensive, and if tt's get you hooked i'm certain you'll be able to justify a dedicated tt bike.

when i entered my only tt (the 24hr one) i thought i'd need a suitable bike for the task (got it second hand, but pristine), it was a rushed purchase and served me well so far. i took it out on several other rides, but i use it mainly for training indoors now.
Title: Re: Wattage Required to do 40k for one hour.
Post by: DuncanM on February 05, 2018, 05:01:54 pm
That pdf is ace, thanks Sam D. As an ex aerodynamics student it's right up my street. :)
I'll have to get some aerobars and see what that does to my position. Stem and seatpost (maybe I can just spin this around) are attainable within budget too, if necessary, but I'll try one step at a time.  :)
Thanks everyone, and sorry for the thread hijack!
Title: Re: Wattage Required to do 40k for one hour.
Post by: Karla on February 05, 2018, 05:09:09 pm
Good general rules of thumb
- Tribars, skinsuit and aero helmet are all good investments. 
- For the helmet, get a proper one, not one of these 'aero road helmets' - they're no better than a backwards cycling cap and for the likelihood you'll actually fall off in a TT, you might as well go bareheaded.  The Bell Javelin and Giro Selector can be picked up pretty cheap these days, but are good solid all-round bets. 
- Set the tribars up so your hands are basically touching in the middle. 
-If you're worried about the length of the headtube, get tribars that place the bars under or in front of the handlebars rather than on top, so the arm pads can lie directly on the bars. These Ritchey ones (http://www.chainreactioncycles.com/ritchey-pro-sliver-clip-on/rp-prod130403?utm_source=awin&utm_medium=link&utm_campaign=ASAP%20Compare%20Ltd&awc=2698_1517849335_53120dbe459a0b3cbed8e8e115f2c5c6) would do the job, as would some similar ones made by 3T or the low mount ones made by Zipp. 
- To get your bars even lower, fit a steeper stem.  Planet X tend too be a good source of these. 
- Ride around in your TT position a lot to adapt yourself to it.  If you set up a super-aggressive position straight away and race in nit without practice, you'll be down on power.   
- Don't worry about your laid back position.  Massively forward tri positions have gone out of favour in the TT world: the thinking these days is that getting your saddle low is really important aerodynamically, and pushing it back will allow you to do that without losing too much power - you'll have to adapt to the tighter hip angle but to an extent that's trainable.  Also, excessively high and forward saddles are bad for bike handling. 

Testing
Since you've got a power meter, a Chung test (http://fitwerx.com/ask-fitwerx-article-archive/your-power-meter-is-the-best-wind-tunnel-available/) is the best way to estimate your drag coefficient.  Basically you ride round in circles, the algorithm shunts all the unknown variables into 'virtual elevation' and then you alter your CdA until VE = Zero.  There's free software available that allows you to do this: see Golden Cheetah (http://www.goldencheetah.org/).

Ideally you want somewhere with zero wind and traffic, and a constant surface so your rolling resistance stays the same - i.e. a velodrome.  Outside, it can be quite hard to control those so you won't be able to fine tune, only to get a rough idea, but the circular nature of the course means that you can gauge the accuracy of the test by how well all the VE values line up at the end of each lap.

The quick way to do this is to pay someone to do this for you in a velodrome, but if you don't have a TT bike yet, don't spend £500 on doing that, put it towards any of the things above which are all low hanging fruit.

[SD beat me to it on the Chung testing link]
Title: Re: Wattage Required to do 40k for one hour.
Post by: phantasmagoriana on February 07, 2018, 06:08:36 pm
You could do a lot better than that with Robert Chung’s virtual-elevation method, described here (http://anonymous.coward.free.fr/wattage/cda/indirect-cda.pdf) (PDF).

Oh, I've met him! (Wasn't anything to do with cycling; related to boyfriend's work...)
Title: Re: Wattage Required to do 40k for one hour.
Post by: Samuel D on February 07, 2018, 08:53:24 pm
You sure it wasn’t another Robert Chung? If so, what does he do for a living?
Title: Re: Wattage Required to do 40k for one hour.
Post by: phantasmagoriana on February 07, 2018, 09:28:45 pm
You sure it wasn’t another Robert Chung? If so, what does he do for a living?

Definitely the same person, because he did mention his cycling stuff (it was at a data visualisation workshop thing - I only tagged along for a meal as I'm not an academic but I like eating...).
Title: Re: Wattage Required to do 40k for one hour.
Post by: Samuel D on February 07, 2018, 09:40:20 pm
Cool! His virtual-elevation method is such an elegant use of data. I wish I had thought of it.