Power Meter Recomendation

nrhorwitz said:

Alot of differences.

The only one huge difference you want to keep in your mind is the reliability factor. SRM is more reliable than the Powertap plus you may have to make few changes to the powertap to withstand rain.

If you are talking about the Powertap standard or pro, would you mind letting me know what mods can be done to improve water resistance? Sounds interesting...

daveryanwyoming said:

Well not with a dynamometer🙂

I got hooked on power meters by riding a friend's PT equipped bike and did the standard 20 minute tests, sprints and such. My best efforts on the Ergomo match very closely allowing for drive train power losses. For instance my best 20 on the Ergomo was 9 watts higher than my best 20 on the PT with the efforts less than a week apart from each other. I also ride ergs at the gym and my current intervals match very well in terms of RPE and ability to complete a given set at a given power level. Nope, it's not calibrated in a bureau of standards sense but I trust the numbers and I don't notice any variability from ride to ride. So as far as I'm concerned the calibration seems quite good. Whether 300W on mine matches 300W on someone else's isn't a big concern, that's what races are for.

Well...at least that's a little better than I was expecting. Any chance your friend will let you borrow the PT?

Or, for a quick check, just put the PT wheel on your bike and mount the bike on a trainer. Then, you don't even need to transfer the harness, just place your friend's bike "back-to-back" so that the reciever is close enough to your rear wheel to recieve the hub signals. Run through a couple of gears and effort levels and "voila!", you'll have some files to check the ergomo against. Oh yeah...don't forget to "stomp test" the PT to check it's cal and also remember to zero it. 😉

Tom Anhalt said:

.... Then, you don't even need to transfer the harness, just place your friend's bike "back-to-back" so that the reciever is close enough to your rear wheel to recieve the hub signals.

Great idea, I'm sure I could borrow a wheel but was balking at asking for the complete harness. Thanks.

RapDaddyo said:

Are you making this statement based on your personal experience? Because I have >10K miles on my PT SL and have never had any moisture problems. I'm aware of a few who have had moisture problems with pre-SL2.4 PTs, but I know many other PT users who have never had such problems. In fact, the only problem I have had is with frame vibration and that was easily and permanently solved. I really don't know that I would label reliability as a "huge difference." But, hey man, if you've got the hard evidence to back up your assertion, go for it.

I used to have a PT and it went out one time. I've had 2 friends who experienced the same thing.

In my cycling club, Alto Velo has had few members who has experienced the same thing.

BUT I should say, we're in about 10-15% of the whole group of PT owners. I'm not saying that you WILL have problems with it. It's just that the chances are much less if you own a SRM.

Oh yes, the PT's sampling rate is 1.26 versus SRM's 0.1. That may be helpful if you are a sprinter.

Robin

Max358 said:

One post in the string mentioned the altitude function in the Ergomo. I noticed several riders in my area using Ergomos in the last few months. While the OP was torn between the SRM and PT, why avoid the Ergomo? Any beefs from anyone?

I think it's a great powermeter. The only downside I'm seeing (Actually two) are:

1. It measures the power on the left side (your left leg).
2. Its sampling rate is 1.0 second (not good if you're a trackie)

Other than that, it is a GREAT powermeter. The sweet thing about this is that you can see your TSS score while cycling.

Robin

nrhorwitz said:

the PT's sampling rate is 1.26 versus SRM's 0.1. That may be helpful if you are a sprinter.

The SRM PCIV allows you to record data as frequently as every 0.1 s - with the newer PCV, you're limited to either 1.0 (earlier PCVs) or 0.5 (later PCVs) s.

So basically if you are coaching someone, would you tell them to get an SRM?

Roadie_scum said:

If you are talking about the Powertap standard or pro, would you mind letting me know what mods can be done to improve water resistance? Sounds interesting...

From [email hidden] (I'm copying and pasting here) from a guy who really knows his stuff about Powertap (Chris Cleeland)

Quoted message said:

Here is a tip that seems to work. Fairly often the PT stops working in
heavy rain. Many times it is water in the contacts between the CPU and
the cradle (a problem that occurs with many computers, not just PT's).
When I take it out of the cradle and blow off the excess water from the
contacts in the cradle it works again.

If that's the case, then get to the nearest auto parts store (e.g.,
AutoZone in the US) and ask for "Tuneup grease" or "Dielectric grease".
This is the stuff that's supposed to be smeared on the inside of spark
plug wire boots to insure that they can be removed, but won't conduct
electricity.
Squeeze a liberal portion of this on to your finger, then smear it all
over the contacts both on the cradle and on the back of the CPU. This
will keep water and moisture out of the contacts, but it will allow the
physical connection btw. nub on the back of the CPU and the leaf in the
cradle/shoe.

Quoted message said:

The other issue is water in the hub itself. That is more rare and
happens to me probably 1/3 of the time in rain. It also happens in heavy
fog occasionally. When it does a simple overnight period where you take
the cover off is enough to dry it out and get things working again.

I'd suggest using tuneup grease here, too. It's a little thicker than
Pedro's syngrease, and doesn't break down in heat as much. Plus, if it
does break down, it won't affect electrical connections.
Here's a link describing Permatex's product:

permatex.comprodidx.aspOpen ↗

And a link to some place selling it online:

shop.store.yahoo.comdigr.htmlOpen ↗

-cj

acoggan said:

The SRM PCIV allows you to record data as frequently as every 0.1 s - with the newer PCV, you're limited to either 1.0 (earlier PCVs) or 0.5 (later PCVs) s.

Isn't that like a regression with the newer generations of PCV's?

kopride said:

So basically if you are coaching someone, would you tell them to get an SRM?

No. If you're a trackie, I'd recommed SRM (but the one with 0.1 sampling rate, that's only available with PCIV)

If you're a road cyclist, Ergomo or power tap is fine. Just keep this in mind, If you're going to use Ergomo for years to come, then you make the decision to switch to SRM or Powertap, there may be a chance you'll see a slight difference between your Ergomo data and others.

For instance, there was a rider who came by home last May with all the gizmos on his handlebars (SRM, Ergomo, Garmin, etc). He was showing about 280 watts average on his SRM but about 308 on his Ergomo. It's because his left leg is much more powerful than his right leg.

So if you're going to stick with a powermeter for a long time, It's fine to go with Ergomo or Powertap which is certainly a much cheaper option.

nrhorwitz said:

I think it's a great powermeter. The only downside I'm seeing (Actually two) are:

1. It measures the power on the left side (your left leg).
2. Its sampling rate is 1.0 second (not good if you're a trackie)

Other than that, it is a GREAT powermeter. The sweet thing about this is that you can see your TSS score while cycling.

Robin

That really is sweet! It'd make it so much the easier to know when I've gotten the desired amount of stress in. Now if only the Ergomo guys would do independent power sampling for each leg.

nrhorwitz said:

No. If you're a trackie, I'd recommed SRM (but the one with 0.1 sampling rate, that's only available with PCIV)

Are you a trackie or do you coach trackies? I am and I do. I suppose the five of us trackie PT owners at my local track training group are getting next to no use from our PTs then?🙄

There are some very specific applications of data analysis that the faster recording rate will be useful for, but even then you'll have to try and get your hands on a PCIV and they are not always readily available.

The PT does a fine job on the track. For 1/3rd the price of a track SRM.

Would I use an SRM? Of course. Am I happy with the PT on my track bike? Of course.

Alex Simmons said:

Are you a trackie or do you coach trackies? I am and I do. I suppose the five of us trackie PT owners at my local track training group are getting next to no use from our PTs then?🙄

There are some very specific applications of data analysis that the faster recording rate will be useful for, but even then you'll have to try and get your hands on a PCIV and they are not always readily available.

The PT does a fine job on the track. For 1/3rd the price of a track SRM.

Would I use an SRM? Of course. Am I happy with the PT on my track bike? Of course.

If I made it sound as if Powertap is worthless on the track, That wasn't my intention. What I am trying to do with my message is that I would recommend SRM (Clearly you're right, with PCIV) over Powertap because of its sampling rate and especially with the 200m.

If SRM was not an option, I would definitely recommend to any athlete that they get at least a powermeter over nothing at the Track. It's my personal belief and what I've seen with all the trackies' power data: Powermeter is extremely valuable to trackies when analyzing their track data. A good example is Doug Northcott who I just did a case study on (http://www.thresholdpower.com/cs_dougnorthcott.html).

Clearly it boils down to the fact that winners win by milliseconds.

nrhorwitz said:

If I made it sound as if Powertap is worthless on the track, That wasn't my intention. What I am trying to do with my message is that I would recommend SRM (Clearly you're right, with PCIV) over Powertap because of its sampling rate and especially with the 200m.

If SRM was not an option, I would definitely recommend to any athlete that they get at least a powermeter over nothing at the Track. It's my personal belief and what I've seen with all the trackies' power data: Powermeter is extremely valuable to trackies when analyzing their track data. A good example is Doug Northcott who I just did a case study on (thresholdpower.comcs dougnorthcott.htmlOpen ↗).

Clearly it boils down to the fact that winners win by milliseconds.

I remember reading that one a while back. Nice report.

Sorry, bit frustrated lately with some who are not willing to share their real identities but make all sort of statments and/or engage in duplicitous behaviour. Clearly that doesn't apply to you.

Alex Simmons said:

I remember reading that one a while back. Nice report.

Sorry, bit frustrated lately with some who are not willing to share their real identities but make all sort of statments and/or engage in duplicitous behaviour. Clearly that doesn't apply to you.

No worries, I appreciate the fact you guys are making this powermeter situation into a valuable discussion.