SRAM Force
spindle (crankshaft) type
power meter
battery replacement.
A while back, when starting up my cycle computer,
I started getting occasional warnings that the
power meter battery was LOW,
and when I connected it to my smartphone app,
it showed there was still about 25% charge,
so I ignored it and kept using it,
but recently I've been getting the warning
almost every time I start up, so
I replaced the battery.
When I first started using the power meter,
it came with a monitor battery, and
based on my usage frequency (←which honestly is meaningless information),
it lasted about 15 months.
But the real value of this post is
as another reminder that "you need to be careful about battery type."
For details, check out (this article).
Anyway, with this spindle-type power meter,
when I do single-leg pedaling with just my right foot,
the power reading shows nothing at all.
When I pedal with just my left foot,
roughly double the power shows up
on the cycle computer.
SRAM's spindle-type power meter
replaces a standard crankset
with a component where the left crank arm
and crankshaft are integrated as one piece,
and if the power measurement is based on
spindle deflection,
you'd think the right crank pedal stroke would also
show a power reading.
So I thought maybe
the spindle-type power meter actually has
the strain gauge in the left crank arm?
In that case, "spindle-type" might not mean
"because the strain gauge is in the spindle"
but rather "because the battery is located there."
With a spider-type power meter,
you replace just the right spider section
of a standard crankset (which has nothing built into either crank arm)
with a strain gauge + battery case component,
so there's no doubt the strain gauge is in the spider.
I did more experimenting with the spindle-type power meter,
(after shifting to a straight chainline)
and found that even when I pedal backward,
power isn't being measured.
Even if I coast on flat ground and forcefully backpedal
from top dead center on the left pedal,
it doesn't show even 1 watt.
It seems to be detecting the crank rotation direction.
So the strain gauge isn't in the crank arm,
but rather in the spindle itself, as the name suggests.
Moreover, the recently updated
Rival E1 crankset has
large holes drilled in the crank arms—
a somewhatridiculous design—
and the spindle-type power meter uses
the same shaped left crank arm, which makes it unlikely
they're hiding a strain gauge in the crank arm section.
So after all, the power meter they call "spindle-type"
does seem to have
the strain gauge in the spindle portion.
When I'm connecting the power meter right after
starting the cycle computer (when it's not yet detected)
and I pedal to get it to connect,
backpedaling works too, so
they're not completely ignoring all reverse rotation.
spindle (crankshaft) type
power meter
battery replacement.
A while back, when starting up my cycle computer,
I started getting occasional warnings that the
power meter battery was LOW,
and when I connected it to my smartphone app,
it showed there was still about 25% charge,
so I ignored it and kept using it,
but recently I've been getting the warning
almost every time I start up, so
I replaced the battery.
When I first started using the power meter,
it came with a monitor battery, and
based on my usage frequency (←which honestly is meaningless information),
it lasted about 15 months.
But the real value of this post is
as another reminder that "you need to be careful about battery type."
For details, check out (this article).
Anyway, with this spindle-type power meter,
when I do single-leg pedaling with just my right foot,
the power reading shows nothing at all.
When I pedal with just my left foot,
roughly double the power shows up
on the cycle computer.
SRAM's spindle-type power meter
replaces a standard crankset
with a component where the left crank arm
and crankshaft are integrated as one piece,
and if the power measurement is based on
spindle deflection,
you'd think the right crank pedal stroke would also
show a power reading.
So I thought maybe
the spindle-type power meter actually has
the strain gauge in the left crank arm?
In that case, "spindle-type" might not mean
"because the strain gauge is in the spindle"
but rather "because the battery is located there."
With a spider-type power meter,
you replace just the right spider section
of a standard crankset (which has nothing built into either crank arm)
with a strain gauge + battery case component,
so there's no doubt the strain gauge is in the spider.
I did more experimenting with the spindle-type power meter,
(after shifting to a straight chainline)
and found that even when I pedal backward,
power isn't being measured.
Even if I coast on flat ground and forcefully backpedal
from top dead center on the left pedal,
it doesn't show even 1 watt.
It seems to be detecting the crank rotation direction.
So the strain gauge isn't in the crank arm,
but rather in the spindle itself, as the name suggests.
Moreover, the recently updated
Rival E1 crankset has
large holes drilled in the crank arms—
a somewhat
and the spindle-type power meter uses
the same shaped left crank arm, which makes it unlikely
they're hiding a strain gauge in the crank arm section.
So after all, the power meter they call "spindle-type"
does seem to have
the strain gauge in the spindle portion.
When I'm connecting the power meter right after
starting the cycle computer (when it's not yet detected)
and I pedal to get it to connect,
backpedaling works too, so
they're not completely ignoring all reverse rotation.