jsk

Interesting thread. I recall originally reading about how finicky the Garmin Vectors were to set up, but it sounds like Powertap has solved that issue with the P1's. Glad to hear that some folks have been using the P1's on the track and are happy with them.

I'm ordering the parts to build my first track bike now and have decided to go with the P1's. I just couldn't justify the cost of an SRM that would be only used on the track. The P1's will get used for both track and road TT, and I can also put them on my trainer bike to check the accuracy of my smart trainer; so even though they're still pretty expensive I feel like I'll get enough use out of them to justify it.

ruudlaff

I use the P1s on my road bikes and once I'm back on the track I will have no hesitation in using them there too, they have been nothing but perfect

jsk

Glad to hear it. I think Saris/Powertap makes good stuff, I've been really happy with the Powertap hubs I've used in the past, very reliable.

Relik

since i first posted about the P1s, i got a cervelo T4 which has more BB drop than i think most track bikes.. right away i was clipping the pedals on the banking when i wasn't going all that slow.. this included a scratch race neutral roll-out lap.. thankfully i stayed upright but that put an end to using those pedals on that bike.. i found my vectors would be clipping at the same angle but i easily ground about a centimeter and a half chamfer (5/8" for you imperialists) off the bottom end of them and they have worked great.. i've never clipped the vectors with that chamfer added.. but when i used the P1s on my Fuji i never once clipped them so i think they are fine on most bikes but consider the BB drop if you're thinking about them..

jsk

Yeah the T4 has a pretty low bottom bracket as far as track bikes go from what I've read. I'll be riding a Dixie Flyer BTB, which only has 45mm BB drop so I think I should be OK especially on my home track which is 333m concrete (Alkek). Definitley something to keep in mind though.

jfiveeight

60mm BB drop on the T4. jsk, I have a BTB and have been on a 333m track with no issues even track standing and rolling up to the top at a few mph.

ruudlaff

Hmm, I may have to have a bit of a play with this then, I'm putting mine on a Planet X Pro Carbon Track with a 57mm drop. Relik, what length cranks are you using?

carleton

The PowerTap P1 is $1,200 without a head unit.
The SRM Track is $1,700 without a head unit.

I firmly believe that the SRM track is worth the extra $500.

The promise of "I can use this on all of my bikes!" is alluring, but if you are serious enough to consider having a power meter on your bike for track and plan on analyzing the files, then maybe just spring for the proven SRM. That way you can run whatever pedals you want and you don't have to wait 9s to get data from your ride.

Personally, I don't think most people either need a power meter or would actually analyze the data if they had one. I firmly believe that speed, cadence, distance, and heart rate tell enough of the story of the ride. Paying an extra $1,200 - $1,700 isn't worth it for what you get.

(I've owned 2 SRMs and 2 Powertaps on various bikes over the years and analyzed years worth of data.)

Power meters are only valuable if you use them, calibrate them, download all of the data, analyze it, and make changes based on the power data. If you make your changes based on speed, cadence, distance, and/or HR data, then you didn't need the power data. Your human body is the most sensitive instrument in the system.

I'm not saying that power meters are useless. The big questions are: Are they worth the added expense? Will I analyze the data and make changes based on it?

I can install a turbo boost and air/fuel mix gauges on my dashboard, but if I don't know what the numbers mean nor make any changes based on them, then why bother

jsk

I got the P1's for $1079 with DCR's discount code for CleverTraining.com, so it's a $600+ difference that - to me - isn't worth it for something I'd get less use out of.

I currently use PowerTap wheels on my road and TT bikes, and have been thinking about moving away from those to crank- or pedal-based power for a while now. So being able to use the pedals on multiple bikes makes a lot of sense for me. It also means I can sell my PowerTap Jet+ Disc and get a Zipp disc + track-conversion kit and that way have a disc I can use for both track and road-TT.

Not sure what this 9s nonsense is about. Sure, the P1 pedals go to sleep when not in use. In fact all power meters do this to preserve battery life, although the exact mechanism for waking them up may vary. My Powertap wheels do the same thing and it's a total non-issue. Give the rear wheel a spin and do the zero-offset calibration on the head-unit before you start your ride and you're good to go. IMHO this would especially be a nonissue on the track, since the simple act of rolling your bike to the start line and getting the cranks to the starting position will be enough to wake up the meter.

I find the second half of your post pretty condescending. I may be new to the track; but I've been racing and training with power on the road for a while now, and I am well aware of what it is and isn't good for. For me, it's a useful tool.

taras0000

What was so condescending about that post? It's a pretty generic post about the pros/cons of a PM. You have to remember that just because someone responds to a thread you started, doesn't mean that the info given will be only meant for you. Hell, he didn't even quote you, nor did you start the thread. For someone else who is pondering the purchase of a PM, but doesn't know what to do with the info, they can save themselves $1000+ that can be better spent on coaching or track time. Lot's of people can get caught up in acquiring gear just because they can afford it (sometimes they can't, but will purchase because they think they will benefit). If you know what to do with a PM, great. If the opinion offered is of no consequence to you, then what do you care. Someone else may benefit from it.

carleton

I don't know why you took offense to my post. I've said all of those things in the past here and none of it was directed to anyone in particular.

Unfortunately, many (most?) roadies-turned-trackies think that:

- Track racing is just a trimmed-down version of road racing.
- Anything great for the road is great for the track.
- "I know a lot about road riding/racing. How hard can track be?...lol"

Track racing isn't difficult...but it is different. If you hold any (or all 3) of the opinions above, it will hinder your growth as a track racer.

Saying that, "Not sure what this 9s nonsense is about. Sure, the P1 pedals go to sleep when not in use. In fact all power meters do this to preserve battery life, although the exact mechanism for waking them up may vary. My Powertap wheels do the same thing and it's a total non-issue." illustrates that you don't know how important the first few seconds of any standing start time trial event are. There is a reason that PowerTap power meters are not popular on the track If you asked, maybe you'd find out why

Saying, "I know a lot about road riding/racing. How hard can track be?...lol" is like saying, "I know how to play electric guitar. How hard can classical guitar be? There aren't even any pedals or amps to deal with...lol" Again...similar but very different.

Further, I'm very familiar with power meters and their pros and cons. I'm also very familiar with data collection and analysis. I wrote that post to possibly save people some money and help them understand that they aren't missing anything by not having a power meter.

Maybe you got mad because you've already done everything that I advised against for the reasons stated

jsk

Sorry, but if you're claiming that there's a 9s delay in getting data from the P1's, you need to back that up with facts. As far as I can determine it's just not true. As long as you ensure the pedals are awake, you won't be missing data from your standing start. Maybe you'd rather not have to deal with that step but for me it's a worthwhile trade-off for the other advantages of the pedals.

If you want to argue that SRM is the best option for measuring power on the track that's fine. I'll even agree with you.

But if you're arguing that anything less than an SRM you might as well just use HR and speed, we'll have to agree to disagree.

Except that I didn't say that. I said I understood the benefits of training and racing with power. I still have plenty to learn about the track, but my focus on the track will still be the endurance side of things, not sprint. So when it comes to using power to pace and judge interval workouts, or analyze race results, yes I expect there's some carryover even if there are differences.

OK, but the topic under discussion wasn't whether a power meter is worth it or not. The topic was whether there are any track-specific limitations of the P1 pedals and if so what are they. You seem to feel there are, but haven't given any compelling arguments to back up that position.

Relik

172.5

ruudlaff

I don't know if there's been a misunderstanding or not, but one thing I will point out about my use of powertaps...there isn't missing information, but there is a definite lag between whats going through the pedals and whats shown on the screen. I would be surprised if it was as much as 9 seconds, but anywhere between 1-5 wouldn't surprise me.

carleton

I'm trying to avoid arguing with JSK.

It's not about what's on the screen. Actually (having used 2 PowerTap systems and 2 SRM systems) what shows on the screen can be (and is probably being) smoothed (averaged) anyway.

What's most important is what is in the file when you are at home analyzing the data. That's where the "gains" happen.

For all intents and purposes, the only thing that's important to view when on the bike is steady-state stuff way after the start. It's also key to review max values after the effort (especially for sprinters).

But, again, the most important thing is to review later at home. If we aren't doing that, then we wasted our money.

That being said, ANY being missing from your effort is bad. One of the biggest mistakes that newbie pursuiters make is going out too hard at the beginning...especially during a big event when adrenaline is pumping. As the saying goes, "The first 3 rules of Pursuiting are: 1) Don't start too fast. 2) Don't start too fast. 3) Don't start too fast."

Why? Because dumping too much glycogen in the first few seconds of the event will have a measurable negative affect on the end of the event.

If your power meter misses your standing start, how will you know if you started out too hard?

This is why I wonder if this power meter is good for track.

This is a road power meter. The first few seconds of a road ride/race are inconsequential in terms of data analysis. They are key for track events.

jsk

Depending on which field you're using on the head unit, there will be smoothing in the displayed value which can affect how quickly the number updates. I usually prefer to use 3s and/or 10s on the display because they're more useful for pacing efforts. But even the 'instantaneous' power is a 1s average, because that's the the maximum resolution that the ANT+ protocol supports. Just to be clear, this is true for all power meters if you're using an ANT+ head-unit such as a Garmin. SRM gets around this by using a private protocol with the PCX head units, but even SRM meters can only report 1s data to a Garmin or other ANT+ device. There may also be a bit of display lag on some Garmins depending on which model/CPU, how many sensors you have connected, whether you're using routing, etc. But again that's a display issue, doesn't affect the recorded data.

That doesn't mean the power meter is only measuring power once per second; in the case of the P1 pedals, 40 measurements are taken per pedal stroke. That data gets averaged to 1s for transmission over ANT+, but I believe the high-resolution data is available over bluetooth when using their PowerTap mobile application (which is iOS only at this point, so I can't try it until they release for Android).

I think in the future we're going to see more head units using BLE instead of (or in addition to) ANT+, in which case higher resolution data should be available.

Having used PowerTap hubs for a while now, my experience is that they just work. The P1 pedals have been out for a while now and the feedback seems pretty good in this regard also. Very reliable and accurate. As far as missing data, in my experience it's just not an issue. As long as the meter is awake when you start your effort, you won't miss anything. Waking up the meter is a trivial step, and it's impossible to forget if you're in the habit of performing a zero-offset calibration on the head unit (always a good idea if you care about the highest accuracy).

My initial impressions after installing the P1 pedals is positive. Installing them is a breeze. As far as track usage I don't see any downsides except for the possible clearance issue if you have a lower bottom bracket and/or longer crank arms. On my bike (45mm BB drop, 170mm crank length) it's not at all an issue. And if you pedal with any toe-down/ankling it's even less of an issue since the lowest part of the pedal is behind the spindle. Too soon for me to say whether the left/right data will be useful, but it could be interesting. WKO+ 4 has lots of charts for analyzing L/R balance, I'll watch the training video they have on the subject once I get some time.

ruudlaff

Used the PowerTap P1s last night on the track with 165 cranks on a Planet X frame - absolutely no problem with clearance. Data seems ok too, although I didn't do any standing start work