Road Cycling

Roady · 6 Feb 2017 at 10:54

BennyC said:
Gloves stayed on though

Benny with the granny gloves! Retro!

BennyC said:
Staaaaahhhppp.

Lead times are pap at the moment, as ever

If it's in stock you might get it before Friday. Or possibly end February. February 2018.

SoliD said:
Ive never ridden on the road in proper waterproof trousers but have proper waterproofs.

I've got 'full' waterproofs I wear in real rain in when commuting. They actually got used a couple of times the last few weeks when I hadn't worn them for probably 9-10 months!

They're ok for commuting/base effort z1/z2 kinda stuff. Anything more than that it's better to wear tights/warmers with some basic resistance, so just dry out rather than boil in the bag trousers (which tend to stay damp!).

SoliD said:
Have you still got cadence attached with the PWM? If so Garmin will ignore this and use your PWM cadence. so not sure why you're still getting spikes.

I've not disconnected any sensors, just scanned for 'new' and added the power sensor, it didn't list any others. Had speed & Cadence sensors previously (and still attached) so just assumed they were still being used.

The Powertap site says 'Motion-based electronics eliminates additional sensors.' so it could be replacing my cadence pod. I'll do a rescan tomorrow and see if I have multiple cadence sensors shown.

SoliD · 6 Feb 2017 at 11:26

Roady said:
The Powertap site says 'Motion-based electronics eliminates additional sensors.' so it could be replacing my cadence pod. I'll do a rescan tomorrow and see if I have multiple cadence sensors shown.

You can pair up your cadence but the garmin will ignore it. There is a hierarchy to the way it reads data.

Roady · 6 Feb 2017 at 11:35

But a 'Power sensor' couldn't/shouldn't also contain cadence data could it? Especially when a dedicated 'Cadence sensor' is already selected and providing data.

Head unit is an ELEMNT, I'm not 100% convinced with it's methodology as I don't know the unit inside out (like I knew my 810). I'll clear all sensors and re add them. I know it'll pick up multiple sensors as it picks up two of my HRM (ANT+ & BTLE) and has picked up multiple speed/cadence before when in my garage (where multiple sensors were present).

xdcx · 6 Feb 2017 at 11:37

My 810 uses cadence readings from my Vector pedals even if I pair up the cadence specific Garmin sensor. Not sure how the ELEMNT handles things but in the world of Garmin to Garmin SoliD is correct.

Roady · 6 Feb 2017 at 11:51

Does it list a 'different' cadence sensor (so lists 2)?

SoliD · 6 Feb 2017 at 11:54

Roady said:
But a 'Power sensor' couldn't/shouldn't also contain cadence data could it? Especially when a dedicated 'Cadence sensor' is already selected and providing data.

Head unit is an ELEMNT, I'm not 100% convinced with it's methodology as I don't know the unit inside out (like I knew my 810). I'll clear all sensors and re add them. I know it'll pick up multiple sensors as it picks up two of my HRM (ANT+ & BTLE) and has picked up multiple speed/cadence before when in my garage (where multiple sensors were present).

A Power Meter should absolutely read/produce/write cadence data for crank/pedal based meters, how else do you think power is measured?

Given that power = force x distance (or displacement) / time
And, displacement / time = velocity
A simplified equation is:
power = force x velocity

And that is the key to understanding how a power meter works. It’s essentially applying that equation to a given part of the bike – be that BB axle, crank, hub, pedal axle etc.

whereby, the speed of the movement, or angular velocity is measured and multiplied by the size of the force – force having been calculated by strain gauges. With those figures in hand the energy cost is therefore quantifiable as power (watts).

touch · 6 Feb 2017 at 11:59

SoliD said:
A Power Meter should absolutely read/produce/write cadence data, how else do you think power is measured?

How would a power meter measure cadence? Surely it's just an estimate based on power input?

Maybe a pedal-based system could detect rotation of the pedal but I dont know if they do that?

SoliD · 6 Feb 2017 at 12:11

touch said:
How would a power meter measure cadence? Surely it's just an estimate based on power input?

Maybe a pedal-based system could detect rotation of the pedal but I dont know if they do that?

Power = ForcexDistance, so in the case of crank or pedal based, the strain gauges know how far the force has gone (ie Force x Cadence) which is why you have to enter your crank length for these systems in your headunit to give accurate power, so it can work out the circumference and give you the distance that force has actually travelled over. not sure if that makes sense, it does in my head

DCRainmaker explained it better

Roady · 6 Feb 2017 at 12:17

SoliD said:
A Power Meter should absolutely read/produce/write cadence data for crank/pedal based meters, how else do you think power is measured?

I had thought that strain gauges measured the deflection of a known solid in a known state due to torque, which is why they were temperature influenced and generally self contained/sealed units.

I wasn't aware they also measured velocity! :eek:

Thinking about it now, the % of error would be so high if a strain gauge was only measuring 0.0001mm of deflection for the total power calculation. :rolleyes:

BennyC · 6 Feb 2017 at 12:18

touch said:
How would a power meter measure cadence? Surely it's just an estimate based on power input?

Maybe a pedal-based system could detect rotation of the pedal but I dont know if they do that?

Accelerometers?

Bear · 6 Feb 2017 at 12:19

touch said:
How would a power meter measure cadence? Surely it's just an estimate based on power input?

Maybe a pedal-based system could detect rotation of the pedal but I dont know if they do that?

Older crank based systems used to have a magnet, but newer ones now use an accelerometer. Would guess most of them have moved to accelerometers now.

Bear · 6 Feb 2017 at 12:26

Roady said:
I had thought that strain gauges measured the deflection of a known solid in a known state due to torque, which is why they were temperature influenced and generally self contained/sealed units.

I wasn't aware they also measured velocity!

They dont, they only measure force. The velocity comes from the use of a magnet or via an accelerometer which measures cadence.

touch · 6 Feb 2017 at 12:42

SoliD said:
Power = ForcexDistance, so in the case of crank or pedal based, the strain gauges know how far the force has gone (ie Force x Cadence) which is why you have to enter your crank length for these systems in your headunit to give accurate power, so it can work out the circumference and give you the distance that force has actually travelled over. not sure if that makes sense, it does in my head DCRainmaker explained it better

I'm not arguing with your physics - I can see why a value for cadence is required to calculate power. I just didnt know how it could measure cadence.

I guess, as others have now said, it uses accelerometers. That would work for everything except hub-based systems.

SDK^ · 6 Feb 2017 at 12:47

Stages PM's use accelerometers to measure cadence.

Lethal` · 6 Feb 2017 at 13:06

I don't have a power meter but I got one of the new Garmin Speed/Cadence sets. Both use accelerometers. No lining up magnets required and no random 225RPM that I was getting from my Giant cadence sensor.

Roady · 6 Feb 2017 at 14:33

Lethal` said:
I don't have a power meter but I got one of the new Garmin Speed/Cadence sets. Both use accelerometers. No lining up magnets required and no random 225RPM that I was getting from my Giant cadence sensor.

Yeah I'm using the newer ones (with the older GSC10 on my turbo bike), battery life seems incredible on them!

Hmmm... Interesting final comment! I'm seeing 250rpm cadence spikes now, which I wasn't seeing before (which is why I mentioned it)! :rolleyes:

Will remove my cadence sensor tomorrow from the equation completely.

All good info re: PWM's and accelerometers guys :cool:

kiteloopy · 6 Feb 2017 at 14:58

So, out if front mounts.
Anyone aware of a mount that can have three items on it? for example;

Garmin 800...Go-pro session & Garmin Varia bike light?

most 'multi' mounts are one up one down. Just mount one would be so much cleaner on the bike.

touch · 6 Feb 2017 at 15:20

Maybe something like this?
http://www.chainreactioncycles.com/...gclid=CIaYiMri-9ECFWm-7QodFZsF_w&gclsrc=aw.ds

Roady · 6 Feb 2017 at 16:29

touch said:
Maybe something like this?
http://www.chainreactioncycles.com/...gclid=CIaYiMri-9ECFWm-7QodFZsF_w&gclsrc=aw.ds

Good find, hadn't seen one of those before!

kiteloopy said:
Just mount one would be so much cleaner on the bike.

Part of the problem is the vibration along the mount. I had lots of vibration through mine (Superstar combo) with an Edge 810 & VIRB.

Roady · 7 Feb 2017 at 09:03

Quite enjoyed that, my first ride on The Sufferfest app.

It operates very similar to the old videos, with only an added overlay at the top showing current/target Cadence, Heartrate and current/target Power. I expected a little more from it, like it telling you when cadence/power dropped to 'HTFU' and slowing the video if you slowed, but nothing, it does pause a few seconds after you stop pedalling though. Maybe some of the other newer sessions are more 'interactive'. There were times when the old video in the centre is telling you one thing and the overlay at the top is telling you another! :rolleyes:

I had lots of problems setting up sensors, for some reason the app wouldn't pick up anything until I'd rebooted and changed the USB port my Suunto ANT+ adaptor was in to reinstall it. Even then it wouldn't 'see' my GSC10 speed/cadence so could only use the crazy inaccurate cadence from my Vortex Smart. You can see it all over the place, my garmin was a constant 88-94 rpm (S&C to headunit) for the majority of 'The Long Scream' (a TT) yet the app shows 82-122 rpm.

Set my FTP as 270, started the session and noticed 'warmup' efforts at 60W which seemed very low, stopped and looked and my FTP had been changed to 150W in the app. I set it again to 270, exited & reopened, 200W. Weird. Set it as 250W saved & exited and that seemed to save it! Did the session, easily hitting the power levels, checked after finishing and the FTP was back to 235! :rolleyes:

Anyone who's used it for any FTP test kinda stuff? Maybe I need to do one with the app?

EDIT: Noticed my data 'irregularities' (cadence & speed) are similar to Chris', so it could just be the app itself?