tetonrider

when i got power on my MTBs, i was super curious to see how hrTSS corresponded with actually TSS. for me (and for other riders' files i've seen) it is often off by a large margin. the riding for these files tends to be filled with surges due to terrain, though. for more steady riding it might be closer to reality.

globecanvas

For MTB rides I calculate TSS by using HR for the baseline number, then increasing it arbitrarily based on perceived effort. In other words, making a number up.

tetonrider

yeah, but if you're experienced riding with power and you know your body well, you can do a pretty good estimate--possibly better than hrTSS for MTB.

for me, estimates of TSS are far easier on the road--so much less variability.

Andy STi

I can see that, hrTSS often seems low for my ride. Which way was it off for you? Maybe I should bump it up kinda like @globecanvas does. Often thought about doing that.

Andy STi

Also when I nordic ski I have a big difference in my hrTSS based on whether my Garmin 405 is set on run or cycling. I can do a 50km ski with a high z3 low z4 HR and have a TSS vary from 200-500. Have never know what is best. These are workouts that have huge stress so I want to record them but they are kind of in between running and cycling.

Ideas?

tetonrider

in my own experience and from observations of others, i find it varies according to terrain and fitness. what i mean is that some terrain lends itself to riding that is full gas or off (e.g., short ramps followed by descents), so those efforts are more similar to crit riding in a pack. other terrain is smoother. hrTSS seems to underestimate TSS of the former.

also, a well-trained athlete tends to have their HR drop faster after hard efforts vs a lesser-trained athlete. the slower HR drops after an effort the higher hrTSS tends to be--meaning more experienced athletes tend to see lower values from hrTSS than the effort would otherwise indicate.

for my rides and riding, hrTSS most often underestimated TSS when actual power was recorded.

long way of saying "it depends", but i hope that gives you enough info to apply to your own rides & terrain.

globecanvas

For nordic ski I use the HR TSS number directly, figuring that two effects cancel out: on the one hand, it usually feels a godawful lot harder than the TSS number indicates, but on the other hand, it's not bike-specific training.

tetonrider

don't know anything about the algorithm the 405 uses, but here is a guess: does it report higher values if set to run vs cycling? wondering if it somehow attempts to account for coasting. (that's a problem with using HR with most cycling efforts other than ones that are constant power/constant pedaling.)

skiing's a tough one. you could probably just give an activity a swag and it will be good enough. for something like nordic, i would tend to look at my overall HR to see what zone i was mostly in, then manually assign a TSS rather than doing hrTSS. you know what a 100TSS session is like.

my philosophy is that one should either attempt to record all these other activities (skiing, a weight session, running...but where does it end? walking the dog? chasing the kids around the soccer field?), or just record the cycling-related stuff. i generally fall in the latter camp for my own stuff, because the rest of it falls into my general life stuff and is fairly constant throughout the year, on top of cycling.

Andy STi

Good stuff! Some great thoughts and ideas. Thanks guys.

pecos

Need to replace my power meter.
On a budget, and not really concerned about absolute accuracy, but rather consistency, lightness and price.
Has anyone here been racing / training on ibike's Newton? any comments on the ease of use, durability? I understand you have to buy a HR sensor/strap that is either ANT+ compatible or one from ibike. Can you display HR, power, cadence at the same time? I train a lot a night, so how's the display in dim light? do you get a lot of abnormal readings? Another must have for me is the ability to upload workouts to trainingpeaks.

echappist

consistency without accuracy isn't worth much, especially since you are switching between brands

favoring weight over accuracy is the tail wagging the dog. 200 grams at most (powertap pro over a regular rear hub), and 100 grams at the very least (vector). So all in all 100 gram worth of difference

That IBike thing is a CdA estimator, not a strain-gauge based powermeter. if you want to play semantics i guess you could say strain-gauge also doesn't measure power. fair enough, but the associated accuracy with a strain gauge is a few orders of magnitude better than what you get for the IBike.

waterrockets 

Yeah, stay away from iBike for power training. You can find a used PowerTap under $500 pretty easily.

furiousferret

Pecos, I'd look into either Stages or Powertap.

pecos

Few orders of magnitude?

https://www.ibikesports.com/wp-conten...wton-vs-PT.png

echappist

fair enough, 1 or more orders of magnitude.

with any strain gauge, you get down to 1-2% accuracy. now try riding in the wind, or within a group, or when the barometric pressure changes quite a bit, and see how things change.

you want to be an apologist for the CdA estimator, be my guest. But the objective of power measurement is accuracy, and for that, the ibike is sorely lacking in all but the most controlled of environments.

pecos

Yes, I see them on ebay, but $500 is only the tip of the iceberg, right? you have to install them on your wheel, perhaps end up buying new spokes, ANT+ head unit plus other sensors.

The ibike is not bike or wheel specific, which means one PM can be used across many bikes, with only the speed and cadence sensors needed on each bike. You can store up to 3 bikes' configurations.

The Stages is one I'd consider were it not for the fact they don't have a carbon option (I have SRAM RED on all my bikes, replacing the cranks would be too expensive)

echappist

i sold an ant+ powertap 2+ years ago for $530 shipped. they are out there. a casual glance on ebay shows many wheelSETS being sold for ~$400. an ant+ computer is another $100 or so (the Joule)

The "faults" you are pointing out for the other systems are all red herrings as far as training is concerned, whereas the ibike is woefully lacking in the thing it's supposed to do well: providing accurate and consistent power data. It's obvious you've got your mind set on the ibike, which is fine; but at least you could be honest about it and admit that you are seeking hand-wringing reassurance that the ibike is a good tool for training with power. Unfortunately, whether or not you admit it, the ibike fails at the most important thing that a powermeter should do as it doesn't work for many circumstances, including riding indoors, riding in changing conditions, riding in a group, etc.

Dunbar

I wouldn't bother with older used Powertaps at that price. If it fails (remember it's used) it's going to cost you $350 plus shipping to have it upgraded to G3 internals. HOOPS will build you a Powertap G3 rear wheel laced to a Pacenti SL23 or Kinlin XC-279 rim starting at ~$800. So the math doesn't really work out for me on used Powertaps unless they're priced well below $500.

shovelhd

I like the new Chappy. Good advice.

I paid $600 for my used SL+ wheel with Kinlin rim and Sapim spokes, but that was from a friend and it was a while ago. I wouldn't pay more than $400 now.

globecanvas

iBike is not going to fulfill your needs. Or even if it does at first, if you actually use the data you will soon want to upgrade. Simply put, it's not a power meter; it's a power estimating system.

You can run the Rival Stages on Red with no problems or downsides. The Rival crankarm with power meter is about 50g heavier than the Red crankarm, which is still less of a weight penalty than other options. It sounds like price is your main consideration, in which case I would recommend the Stages.

thechemist

stages IS an issue in poor weather. I have had local teammates with issues of stages in the rain and I recall some members hear as well?

I have also seen some pictures of sky training with SRM not stages...not that it matters

globecanvas

I was the one posting about that problem. It was an issue with their first iteration. They have since upgraded the battery compartment seal. For redundancy I also tape up my Stages crankarms. I've had no problems for about 8,000 miles, including riding consistently through the northeast winter. But, I would certainly say a Powertap is more durable/reliable than a Stages.

For full disclosure, I own 3 stages, one quarq, and formerly a powertap. There have been many discussions of pros and cons for all of the systems. Various factors are price, accuracy, durability, and portability. Stages scores well on price and portability. Powertap is slightly worse on price and portability, but better on accuracy and durability. Other options are significantly higher priced.

rankin116

My PT wheel was $400 on Ebay. It's a bit older, Pro+ maybe? A little beat up, but it works.

waterrockets 

Both of mine are from ~2006 and work great.

oespinoza83

My Stages input regarding weather:

I decided to ride yesterday through a route I normally do near my house during the week. It flooded bad in Houston early last week and apparently some of the water was still flooding part of the park. Long story short, I had to ride through water before I was smart enough to turn around and do another route. First water trench was about 2-3 inches so it wasn't horrible. Second section was about 6 inches at least. I didn't want to submerge the Stages in the water so had the left arm straight up as my right foot/pedal were entirely submerged. It sucked and it was stupid. Rode for 90 minutes after doing some tempo/SST work and Stages had no problems whatsoever. True, it wasn't submerged, but it was pretty wet from the splashing.