Powertap questions

guinea

After telling my partner that I'll be doing the Marmotte this year she's decided to get me a cycling related resent to help me meet my goals.

She's decided to get me a powertap. Now, she needs a bit of help deciding which one to go for.

She's set a budget of £1k. I'll need a wheel built (campag) and a display. There are a couple of options that I can see. An elite+ built on to open pro with either the Cyclops system or a garmin 705. Both available under 1k from http://www.cyclepowermeters.com/cycleop ... p-21-c.asp

I guess I could also buy a hub only, add a DT 1.1 rim and go from there, but I don't know where to get that built up.

However, I don't really know the difference between the available hubs and whether the pro, sl or slc are worth the extra cash. I also don't know the best display, but I guess the 705 is far more useful.

Any advice and pointers would be greatfully received.

Alex_Simmons/RST

I would:

- research any issues in the interface between the PT and Garmin unit. At least with a PT CPU you know it will work.

- suggest avoiding the12mm alloy axle model(s)

- choose a good rim, spokes and wheelbuilder, don't skimp on this last point

other than that it's basically just extra price per gram saved (and that's pretty unimportant).

JohnWilky

I wouldn't bother with the 705 just yet. It'll eat too much from your budget. I'd recommend the SL 2.4 with the standard head unit. I'd check out e-bay. This one has an hour left and is currently £440;

http://cgi.ebay.co.uk/POWERTAP-SL-WIREL ... 240%3A1318

Hope that helps.

John.

guinea

Thanks for the pointers folks.

I'm just searching for the best deal now.

guinea

Actually, I have another question.

Promted by another thread on this forum I had a look at the Saris site. It says that the Elite+ does not have Heartrate or Onboard Analysis.

HR I can do without, but I really want to see my power as I go. Can someone confirm that if I go for the Garmin or the Powertap display I'll get to see the amount of work I'm doing live?

jonginge

guinea wrote:

Actually, I have another question.

Promted by another thread on this forum I had a look at the Saris site. It says that the Elite+ does not have Heartrate or Onboard Analysis.

HR I can do without, but I really want to see my power as I go. Can someone confirm that if I go for the Garmin or the Powertap display I'll get to see the amount of work I'm doing live?

I have a Garmin 705 and an Elite+ wheel only combo. You can view live power no problemo on the 705.

pinkbikini

No idea what Onboard Analysis is, although I must have it on my rented Powertap Pro+ !
All models (Elite included) will show your current power output on the screen as you ride. They will also be able to show you the average and max wattage for a specific ride or interval.

I have had a few issues with the PT CPU and HR - walk away from the unit for a minute or two (e.g taking a 'natural break' on a ride) and the HR no longer registers - I have to go through set-up all over again. Only takes about 20 seconds, but have lost count of the number of near-misses I have had whilst fiddling with the CPU and riding :-( Other than that, no probs with the CPU.

Have to say that HR is probably just as important to have for La Marmotte (for the actual event, that is). The powertap is really an effective training tool, and any relevant analysis will probably be done in the comfort of your home, post-ride.

Would also recommend using a small percentage of your budget to get a training plan written for the next 3 months - very valuable.

sergen

pinkbikini wrote:

Have to say that HR is probably just as important to have for La Marmotte (for the actual event, that is). The powertap is really an effective training tool, and any relevant analysis will probably be done in the comfort of your home, post-ride..

I'm not sure that's strictly true, although others on this forum are certainly better informed on these matters than I am. In my experience using HR over a very long-distance ride becomes unreliable due to cardiac drift. The power I can produce when riding at 180bpm, 5 hours into a ride, is far less than the power produced at the same bpm after just 30 minutes.

For use as a pacing tool I'd go with a power meter over a HRM every time.

guinea

Unless I can't live without the powertap I'd rather do the event with my good wheels. The powertap wheel is over 500g heavier.

I'll definitely be getting a training plan made up. If anyone has a recommendation for a London based trainer who can work out power/HR zones and help me meet my goals I'm all ears.

pinkbikini

sergen wrote:

pinkbikini wrote:

Have to say that HR is probably just as important to have for La Marmotte (for the actual event, that is). The powertap is really an effective training tool, and any relevant analysis will probably be done in the comfort of your home, post-ride..

I'm not sure that's strictly true, although others on this forum are certainly better informed on these matters than I am. In my experience using HR over a very long-distance ride becomes unreliable due to cardiac drift. The power I can produce when riding at 180bpm, 5 hours into a ride, is far less than the power produced at the same bpm after just 30 minutes.

For use as a pacing tool I'd go with a power meter over a HRM every time.

Ah, I said 'important', not 'effective'. I only meant that it was important as it allowed you to monitor the stress to your system under extreme duress - long, long climbs and, usually, pretty high temperatures - and hopefully avoid doing yourself any damage. If you want accuracy then I agree, power.

Alex_Simmons/RST

guinea wrote:

Unless I can't live without the powertap I'd rather do the event with my good wheels. The powertap wheel is over 500g heavier.

I'll definitely be getting a training plan made up. If anyone has a recommendation for a London based trainer who can work out power/HR zones and help me meet my goals I'm all ears.

Training plans (HR or power based) provided globally:
http://rst-training.blogspot.com/2009/0 ... plans.html

Alex_Simmons/RST

pinkbikini wrote:

Ah, I said 'important', not 'effective'. I only meant that it was important as it allowed you to monitor the stress to your system under extreme duress - long, long climbs and, usually, pretty high temperatures - and hopefully avoid doing yourself any damage. If you want accuracy then I agree, power.

How does knowing your HR prevent you from doing damage?

pinkbikini

Alex_Simmons/RST wrote:

pinkbikini wrote:

Ah, I said 'important', not 'effective'. I only meant that it was important as it allowed you to monitor the stress to your system under extreme duress - long, long climbs and, usually, pretty high temperatures - and hopefully avoid doing yourself any damage. If you want accuracy then I agree, power.

How does knowing your HR prevent you from doing damage?

Well, for instance last year I saw a rider overdoing it (I thought at least) on the first climb - the Glandon - and, as he appeared to almost pass out on the bike (head went down, legs went) he cycled into the rockface at the side of the road, fell off his bike and cut himself up. Had he been riding within sensible HR limits (I'm guessing he wasn't, but don't know for sure) he might have avoided this. Might have. I just think the HR monitor is a useful monitoring tool. That's all. If you want to flex your superior physiological knowledge on the issue then I'm not going to argue

pinkbikini

guinea, have sent you a pm with details of London-based trainer so you can compare prices and services...

guinea

Thanks again all.

pinkbikini - no pm received

pinkbikini

guinea wrote:

Thanks again all.

pinkbikini - no pm received

Have sent again - hopefully this one will get to you!

oldwelshman

Personally I would get her to buy you a good set of wheels, maybe the dura ace wheels
I have kindly been lent a power tap by some one off this site but so far have not been impressed by it. Maybe some one on here can enlighten me as to how I should get benefit worthy of such an expense compared to HRM?
Alex maybe you can help me.
I have used it several times, maybe I am not setting it up right but I assumed I would get a steady output on the display to monitor my power ootput during training, maybe with a swing of 5 or 10 w, but during climbs and flat intervals with steady effort I get display variations of over 100w!! This is not much use when trying to maintain steady output surely. I checked manual and it states record interval does not affect display.
So if I try to modify my output I will be up and down like a yoyo
SO at some points when it has been quite stable what have I discovered?
WHen I climb out of saddle, my power output goes up? Wow Iknew that all I know now is it goes to between 350 and 600w when climbing out of saddle.
Same for accelerating out of corners, but other than that not really sure what it tells me.
When I am using HR, i get similar, when I get out of saddle my hr goes up, when race gets fast my hr gets up so wht justifies the extra £300 or so?
I did the marmotte last year and cannot think of any use of the power tap on such a ride, in fact would say the same for hr, just ride it as it will hurt either way!!
I have taken off the power tap meter and put it in my pocket on last three rides due to looking at the display and watching it jump round so much and downloaded the data when home.
So all I know is my ride was overall average for one ride 170w, 200 for another, peak 1105w and 1005 for 5s?
I suppose I could just keep it in my pocket, train as normal and just see if my power output increases? But I know it probably will with or without the power tap?
Have I borrowed a dud power tap or just the settings wrong?

Alex_Simmons/RST

The meter is fine.

Power output when riding (aside from trainers) is highly stochastic. That's actually what happens. It's one of the typical observations by most people who are new to PMs.

This is why you have to learn about training with power and not get caught in the trap of training by power (e.g. like trying to chase your power tail as you describe).

You could take some time to read further on how best to use it but sitting and staring at it as you are riding along is not the way to do it.

By increasing the rolling average interval length to say 5 seconds, the power levels will be less jumpy (that's the rolling average of the display, not recording at 5-sec intervals, which is different). The power numbers will still vary every second on the display but (if you are riding along at a consistent effort level) the variances will not be so large. You get used to doing your own running integration of what the display shows.

However, when riding with power for the first time, people are often surprised to learn:
- how variable it is (they are used to HR which doesn't vary much or with any great speed)
- that they barely pedal when going down a slight decline/hill
- how much harder they pedal uphill
- how slack many of their rides actually are (e.g. club runs)

Here are some links to materials on using your power meter:
http://home.trainingpeaks.com/power411.aspx
http://www.cyclecoach.com/index.php?opt ... Itemid=112
http://www.trainwithpower.net/

The tool is only as good as the knowledge of the person using it. You don't blame a power saw for doing a crummy cut if you don't use it properly.

As for a long sportive/Marmotte etc, then it has tremendous value in helping to correctly pace / dose your effort so that you have enough in the tank for a strong finish up le Alpe.

oldwelshman

Thanks for reply Alex, I will try to sort out the set up and look at some of the links you posted.
I was not really surprised to find the power differences between doing 20mph on flat which takes less than 150w as compared to accelerating out of bends taking up to 600w.
As I ride track a lot I am used to smoothing out my effort so would expect smoother power output, except of course for climbs, corners etc.
As for the Marmotte, I am still to be convinced of the use of it due to the fluctuautions I guess some people would find it useful, others not.
For me personally I used hrm as guide. When I race I usually hit around 155 av hr with a max of 170. (On track I hit 170 more easily then road due to higher cadence, very rarely hit 170 on road) so when I did the Marmotte I just made sure I did not go over 155 on any climbs, especially the first couple. For me this worked and I was ok for entire ride, no cramps, no bonking. The most difficult aspect I found of the Marmotte was not trying not to over cook the ride but the psychological effort required to get over the Gallibier.After what seems like an eternity spent climbing up Gallibier and seeing you have 10km of increasing gradient ahead of you I found the Alp at the end relatively easy compared to the 2 hour slog up the Galibier.
If I ever rode it again I would not stop at that feed station half way up

liversedge

Hey Guinea I'm doing La Marmotte too.

Been using a PM for a couple of years now and would agree strongly that PMs are superb for pacing. Typically I climb at threshold during training rides of 4hrs or less (which is 99% of em). But on sportive/long rides I climb at the low-md end of tempo to allow me to keep my endurance. The PM is far more effective than HR for this, esp. on hot days.

HIghly recommend cyclepowermeters.com too, Bob is a top guy and very helpful and knowledgeable.

Join the google wattage group too - the signal/noise ratio there is excellent and the contributors includes really expert guys like Alex Simmons, Hunter Allen, Andy Coggan, Rich Wharton etc etc

Alex_Simmons/RST

oldwelshman wrote:

Thanks for reply Alex, I will try to sort out the set up and look at some of the links you posted.
I was not really surprised to find the power differences between doing 20mph on flat which takes less than 150w as compared to accelerating out of bends taking up to 600w.
As I ride track a lot I am used to smoothing out my effort so would expect smoother power output, except of course for climbs, corners etc.
As for the Marmotte, I am still to be convinced of the use of it due to the fluctuautions I guess some people would find it useful, others not.
For me personally I used hrm as guide. When I race I usually hit around 155 av hr with a max of 170. (On track I hit 170 more easily then road due to higher cadence, very rarely hit 170 on road) so when I did the Marmotte I just made sure I did not go over 155 on any climbs, especially the first couple. For me this worked and I was ok for entire ride, no cramps, no bonking. The most difficult aspect I found of the Marmotte was not trying not to over cook the ride but the psychological effort required to get over the Gallibier.After what seems like an eternity spent climbing up Gallibier and seeing you have 10km of increasing gradient ahead of you I found the Alp at the end relatively easy compared to the 2 hour slog up the Galibier.
If I ever rode it again I would not stop at that feed station half way up

The Marmotte is pretty wild. I have coached for that and provided pacing advice by modelling the course in advance.

Altitude factors also play a role.

Just can't let go of that HR strap eh?

Give it some time and it'll begin to make sense.

Here's a few tips
- get to know how to estimate (soundly) your 1-hour power (FTP)
- understand what Normalised Power is and what it tells you
- begin to appreciate the tremendous benefits that the Performance Manager brings to all that data. You'll need about 3-months of data for it to start to make sense. Once you have a season or two's worth of data, then the info is unbelieveably valuable. It really is a truth meter.

Honestly, the Performance Manager (impulse-response model) is THE killer ap for power meter data.

guinea

I'm just back from holiday and there's even more good info here.

Re whether to get other upgrades rather than the PT, I did think about that, but to be honest, short of replacing the frame at huge cost there's nothing going to increase the performance of my bike. The carbon bike with shamals and chorus are already too good for me

Thanks all.

guinea

I've got the PT now, a couple of weeks early. I ended up getting the Garmin from amazon and the wheel from a local shop.

I got it home last night, stuck a cassette on it and am now looking forward to getting out and hammering for an hour, or five.

What's the best software for analysing the data?

James_London

guinea wrote:

What's the best software for analysing the data?

WKO+, no question
http://home.trainingpeaks.com/wko-deskt ... files.aspx

guinea

Thanks for that James, it looks the business.

Had my first blast around Richmond Park last night with the PT on. It's quite interesing looking at the figures. Gave it everything for an hour and the avg power was 285watts. I've been told that the Garmin over estimates the wattage, but whatever the real figure it I think I more or less performed at my peak.

It's crazy to see it at over 600 watts when stomping up hills and then below 200 on descents when you're still trying hard.

I'll be having a play with WKO+ tonight

James_London

Nice Watts, guinea!

It takes a while to get into WKO+ but it's well worth persevering with. NP, TSS and CTL in particular are very useful measured for understanding and managing your riding.

What did you get for Normalised Power (NP) in WKO+ for the hour and what was 3-lap time? Garmin average is NZAP (non-zero average power) so impacted by coasting though I'm guessing you didn't do a lot of that ;-)

I rarely do a hard Richmond Park hour so am curious what time average power equates to (though obviously it varies hugely with conditions).

[Deleted User]

The user and all related content has been deleted.

guinea

James_London wrote:

Nice Watts, guinea!
What did you get for Normalised Power (NP) in WKO+ for the hour and what was 3-lap time? Garmin average is NZAP (non-zero average power) so impacted by coasting though I'm guessing you didn't do a lot of that ;-)

The time was a 58.44.

I had a couple of slow junctions and held up a little on Broom hill, but otherwise fairly clear.

What will be interesting is to see how the lap times change depending on wind conditions with the same effort.

I'll get my NP tonight.

liversedge

I think James mean't to say that NZAP (non-zero average power) is not affected by coasting. Its the average for all the time you were pedalling. Any stops or freewheeling are not accounted for.

Still, nice watts!

guinea

Yeah, I understood.

However, there is a bit of coasting involved. The descent from Broom Hill and the slow junctions and pedal free moments. The rest is all out pain

Alex_Simmons/RST

guinea wrote:

Thanks for that James, it looks the business.

Had my first blast around Richmond Park last night with the PT on. It's quite interesing looking at the figures. Gave it everything for an hour and the avg power was 285watts. I've been told that the Garmin over estimates the wattage, but whatever the real figure it I think I more or less performed at my peak.

It's crazy to see it at over 600 watts when stomping up hills and then below 200 on descents when you're still trying hard.

I'll be having a play with WKO+ tonight

8)

Yes, you learn very quickly how much of your normal riding can be pretty slack. Wait til you do a normal endurance or bunch ride, instead of trying to hammer like you were. It'll open your eyes.

James_London wrote:

Garmin average is NZAP (non-zero average power)

That's a pretty bad oversight by Garmin and one they appear not to be all that interested in fixing.