Pedal stack

Discuss light weight issues concerning road bikes & parts.
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hlvd
Posts: 161
Joined: Sat Mar 05, 2016 4:54 pm

by hlvd

Hi, I've two bikes, both same frames but one has Look Blades and the other has Garmin Vectors.

The stack on these is 13mm and 17mm and have measured from the pedal plate up to the saddle so both measurements take into account the difference, one being 4mm less.

Now, is this the correct way to do this as the distance from BB to saddle top will be the same and if I've done it correctly, distance to pedal spindle will also be the same.

Hope I've made that understandable, thanks.

sungod
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Location: it's raining, it must be uk

by sungod

pedal stack is measured from spindle axis to the sole of the shoe (at closest point)

all else being equal, you'd set the saddle on the garmin equipped bike a bit higher wrt to bb axis to compensate, this has a slight knock-on effect on saddle fore-aft position, but unlikely to be enough to matter

by Weenie


hlvd
Posts: 161
Joined: Sat Mar 05, 2016 4:54 pm

by hlvd

sungod wrote:pedal stack is measured from spindle axis to the sole of the shoe (at closest point)

all else being equal, you'd set the saddle on the garmin equipped bike a bit higher wrt to bb axis to compensate, this has a slight knock-on effect on saddle fore-aft position, but unlikely to be enough to matter


So you're saying distance from BB to saddle should be the same on both bike's and distance to pedal plate different due to 4mm difference?

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wheelsONfire
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by wheelsONfire

I would love to see how i would end up on a bike fitted by five fitters compared to how i sit.
Just looking at saddle height, setback and cleat position.

Does cleat position differ anyway for setback?
I see many team riders start to sit more forward, ladies seems to have more setback for some reason?
Bikes:

Ax Lightness Vial EVO D
Paduano Racing Fidia
Open *UP*
https://opencycle.com/showcase/the-xplo ... eelsonfire

sungod
Posts: 1662
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

hlvd wrote:
sungod wrote:pedal stack is measured from spindle axis to the sole of the shoe (at closest point)

all else being equal, you'd set the saddle on the garmin equipped bike a bit higher wrt to bb axis to compensate, this has a slight knock-on effect on saddle fore-aft position, but unlikely to be enough to matter


So you're saying distance from BB to saddle should be the same on both bike's and distance to pedal plate different due to 4mm difference?


no

i said "set the saddle on the garmin equipped bike a bit higher wrt to bb axis to compensate"

that's if you want same leg extension at the bottom of the stroke

i also said "all else being equal", if there's any variation in geometry/size between the two bikes, the effects of that also need to be taken into account

hlvd
Posts: 161
Joined: Sat Mar 05, 2016 4:54 pm

by hlvd

hlvd wrote:
sungod wrote:pedal stack is measured from spindle axis to the sole of the shoe (at closest point)

all else being equal, you'd set the saddle on the garmin equipped bike a bit higher wrt to bb axis to compensate, this has a slight knock-on effect on saddle fore-aft position, but unlikely to be enough to matter


So you're saying distance from BB to saddle should be the same on both bike's and distance to pedal plate different due to 4mm difference?


Haha, which is exactly what I've written in my initial post, in a very roundabout way :D

hlvd
Posts: 161
Joined: Sat Mar 05, 2016 4:54 pm

by hlvd

sungod wrote:
hlvd wrote:
sungod wrote:pedal stack is measured from spindle axis to the sole of the shoe (at closest point)

all else being equal, you'd set the saddle on the garmin equipped bike a bit higher wrt to bb axis to compensate, this has a slight knock-on effect on saddle fore-aft position, but unlikely to be enough to matter


So you're saying distance from BB to saddle should be the same on both bike's and distance to pedal plate different due to 4mm difference?


no

i said "set the saddle on the garmin equipped bike a bit higher wrt to bb axis to compensate"

that's if you want same leg extension at the bottom of the stroke

i also said "all else being equal", if there's any variation in geometry/size between the two bikes, the effects of that also need to be taken into account


Ok, sorry if I sound confused, I am, but all my fault.

Top of saddle to pedal axle is same on both at the moment, but difference in 4mm less on the Vectors from saddle to pedal plate to account for higher stack.

Both frames exactly the same.

Thanks for your patience.

sungod
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Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

it's ok :)

the point is this: the increase in garmin pedal stack raises your foot by 4mm with respect to the bb axis

therefore you need to raise the saddle if you want the same maximum leg extension at the bottom of the stroke as what you have with the look pedals

if you imagine a stupidly extreme case where you had not 4, but 400mm pedal stack, see what it does to your leg extension? you would need to raise the saddle a lot to compensate (of course it'd be a terrible ride due to the long lever connecting your feet to the pedals!)

by Weenie


hlvd
Posts: 161
Joined: Sat Mar 05, 2016 4:54 pm

by hlvd

sungod wrote:it's ok :)

the point is this: the increase in garmin pedal stack raises your foot by 4mm with respect to the bb axis

therefore you need to raise the saddle if you want the same maximum leg extension at the bottom of the stroke as what you have with the look pedals

if you imagine a stupidly extreme case where you had not 4, but 400mm pedal stack, see what it does to your leg extension? you would need to raise the saddle a lot to compensate (of course it'd be a terrible ride due to the long lever connecting your feet to the pedals!)


Thanks for your patience, I'll adjust one later.

Many thanks

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