shovelhd

Try not to overshoot your target. That will make it more likely that you will hit them throughout.

valygrl

If you did a 20 minute test and AP was 279, your FTP would be 95% of 279 = 265.

Doge

Your power is decreasing likely because of lactate build up. Not going as hard, or longer rest between and you would not see the drop off. However you may be doing exactly what you want.

For hard 15-25 min TT like efforts on the road junior's NP is always higher than actual power. He does not do the interval training many do so can't comment on that.

jsk

NP being slightly lower than AP for shorter intervals is normal, I think. NP seems to use some sort of trailing/running average, so when you start an interval coming off a rest, NP will influenced at the beginning of the interval by the lower power at the end of the rest. At least, that's what it seems like to me.

echappist

correct. NP starts tabulating at the 31st second of an effort

Alaska Mike

Installed the SRM with 52/36 rings replacing the 50/34s. Didn't re-calibrate slope because the SRM FAQ said it wasn't required. Installed the SRM under-BB magnet for simplicity, and took it out for its maiden voyage this Sunday on an indoor track. While I can't do an accurate A/B with any of my other power meters, it did feel very close to the Quarqs in terms of PE for a given wattage, and the response profile to a short effort mirrored a similar Quarq profile. I'll play with it some more, but it looks like it will work well for me. I didn't notice a meaningful difference with the slightly longer crank arms (175 vs 172.5).

Alaska Mike

Quick question-
How does a SRM with a failing battery indicate the issue? I was riding on an indoor track today, and my power started dropping off as I was accelerating (significantly, but not a sprint effort). I backed off a bit, and then gradually increased the wattage, which seemed to hold fairly well for the remainder of the session.

I recently replaced the chainrings and torqued them to SRM's specs. Could it be them settling in? I noticed this while viewing a 10sec average wattage display, so I didn't think so.

Is there an easy way to check the battery's condition without sending it in?

Thanks for any help. Still figuring this thing out.

tetonrider

do you have an SRM head unit?

what happened when you phoned SRM to check on the service history of the used unit? (i think you said you were going to do that.)

you bought a unit that is (my guess) at least 6, maybe 8 years old. at that time, the battery life was quoted as 1 year (that hasn't been the case for ~4 years now).

how did you get the unit and what was the history?

SRMs don't really "settle in" in the way other meters can (Quarq and any new rings). if one has a unit it may (*may*) change slope a bit...but any further changes are VERY minor. changes in slope on an SRM are -- in my experience -- a sign something may be wrong. the units that have been in service for a while tend to be battle axes.

i've got a number of units in my garage that are 4 years old that have the same slope as when they were new.

just wondering if what you got was problematic before you got your hands on it.

Alaska Mike

I'm using a Garmin Edge 800. I don't have a SRM head unit.
I still haven't called on the service history. I'm not exactly sure how to get the serial number off of it, other than the ANT+ ID.

Looks like I may be sending this one in for service. Since I got it off eBay, the history of it is kinda murky. No documentation or anything else came with it.

I'm actually fairly well trained to repair electronics (an archaic skill-set, to be sure), so I could certainly replace the batteries myself. I'm just wondering if I should send it in for the other stuff that gets looked at.

tetonrider

no, you can't get the power status with that combination....well, not without opening it up for sure. soldering the battery is NBD, esp for you.

ANT+ ID = serial #.

just give SRM a call. you don't know the history and are experiencing issues--seems like exactly the time to at least ask about the service history, if not to send it in outright for check-up, recalibration, etc.

Alaska Mike

Thanks for the info. That was pretty much along the lines I was thinking. Better to have a good baseline to work with, especially given I don't know the history of the unit.

Edit- Called them today and it looks like the unit was last in for service in November of 2012. At least I know it was looked at sometime during its lifetime.

I did a little research and found the cheapest I could get the batteries (price/shipping) up here was $60, and that would take a few weeks because it would require ground shipping (HAZMAT). I have no problem swapping them, but I figure I'll just let SRM do it this time around. Again, all about the baseline.

gsteinb

LIMITS Responds: Says they aren?t a scam (but still lie) | DC Rainmaker

globecanvas

https://en.wikipedia.org/wiki/Hanlon%27s_razor

heppm01

I'm not familiar with the product and only know as much as what I read in the DCR response, but any time you need to rebut that you are not a scam it's almost a sure bet that your company is doomed.

cali_axela

I got my VO2max and LT tested for the first time last week, for free at a new fitness startup downtown. They did it by having me do 30s intervals with 30s rest in between, at increasing wattage by 25w at a time, until I couldn't hold the power level for the full 30s. I quit 20s into the 550w interval. Based on whatever formula they use, said my LT was at 214w. This is very close to what Strava estimated my average power as on longer hard training rides, before I trained with power.

This weekend, I used my new PowerTap rear wheel for the first time, climbing Mt Diablo: my actual average power on the 69 minute climb was 239w. I put it all out there... couldn't even stand up for 10 minutes at the top.

When setting up my training zones based on power, now that I have both a lab test for LT and the PowerTap known average wattage for a ~1 hr all out effort, what should I set my FTP as: somewhere between these two figures (214w lab-tested LT, and 239w recorded average for a 1 hour max effort)?

TheKillerPenguin

Assuming your powertap was properly calibrated, I'd go with the field test + a few watts since your diablo effort was longer than 60min. For the life of me I can't produce the same power indoors, and I think extrapolating ftp from 30sec on 30sec off relies on a bunch of assumptions about anaerobic capability.

Anyway, you've gone as hard as you can for 69 minutes, that number will be more accurate.

cali_axela

Thanks, that's exactly what I was thinking to. I'll set my zones based on an FTP of 240w and see how it goes.

globecanvas

I have a Stages that a friend gave me about a year ago because it didn't work. The pod was cracked when I got it, I super glued it together, it worked again, I put it on my cross bike. After a few months I hit the crankarm on a rock and it cracked in another place, super glued it together again, kept working. This morning I wailed a rock hard enough to take a chunk out of the aluminum crankarm and crack the pod in a third place. Super glued it again. It still works, more or less accurately as far as I can tell -- RPE offroad is not easy to calibrate to watts, but the numbers match my expectations, especially on climbs. I think it's mostly made of super glue at this point.

gsteinb

this is the kind of stuff that makes my head hurt, for real. Because I agree with your sentiment of 'it more or less works as far as I can tell (and that's ok)' and yet most of the time when I'm training day in and day out I'm fighting for single digit wattage improvements (often 1 digit).

globecanvas

Well, it is the cross bike, so that precludes scientifically accurate interval training anyway. I do Z4 type intervals on it but those are mostly in the category of "cilmb this 10-15 minute hill as hard as I can" or "a little less than as hard as I can" as opposed to targeting a specific wattage which would be impossible/dangerous anyway given that I'm grinding up a dirt trail.

shovelhd

I bet Stages would replace it for you.

Hermes

The above describes my training as well.

Hermes

I upgraded Vector to the new Vector 2. This past weekend, I had the Vector 2 on the track bike, time trial bike and road bike. It worked perfectly in all three cases. The head unit is a Garmin 810. The power data looked good and made sense based up efforts and pedal force.

The new pedal pods install in a much better manner and torquing the pedals is easy. The pedal swap is not much harder than changing pedals with the addition of attaching the pedal pods.

Sooooooo, we shall see over time if this system holds up.

spdntrxi

I had to go back to V1 pods.. I think I got a bum V2 pod.. need to get around to sending it back for a swap.

Hermes

Did you do the pedal spindle conversion and upgrade the firmware in the pedals? I took the V2 kit to my bike shop and they rebuilt the Vector pedals. And try new batteries versus the ones sent from Garmin.