Do pedals consume watts?

pbassred

Alternative titles : Will my pedals get easier?, Can I adjust my pedals' friction?

I just fitted new pedals 'cos the guy at work was nagging me about weight (ok, he's right). So I fitted some Boardman SPDs (its a CX bike but the point is the same). I noticed that they don't spin very freely so I wondered if this is wasteful. I know that the accepted advice is that; if they spin freely its time to re grease, but how many watt does it consume? It won't matter to me, ever, but what do top teams with consultant rheologists do?

imposter2.0

You're over-thinking it.

ugo.santalucia

I can assure you top teams don't do rheology.

As above, you are overthinking it

ayjaycee

Methinks someone is trying to extract the urine (at least, I hope so!).

Man Of Lard

Every mechanical interface introduces frictional losses...

Pedal/pedal axle
Crank axle/bottom bracket
Chainring/chain
Chain links
Chain/rear sprocket
Derailleur jockey wheels
Wheel axle/frame
Tyre deformation
Tyre/road

So where will you start?

pbassred

Only idle speculation on a lazy public holiday morning, I can assure you. I suppose I should have written "tribology", but I was thinking about how grease moves out of the way.
So, top teams not interested in lubricants or bearing friction losses. Surprising, considering that Team Sky stock stems in 1mm steps. Good opportunity for someone.

Man Of Lard

Of course they're interested​. They're trying to win races. If they can minimise the losses then conversely that maximises the output of their riders - especially compared to their rivals.

I think we're all assuming that you are not planning on imminently challenging for GC in the Giro here?

trivial_poursuivant

It has been thoroughly researched and it has been concluded that pedals do indeed waste watts. But it was found that be removing them from the system the bike doesn't go very far.

ugo.santalucia

pbassred wrote:

Only idle speculation on a lazy public holiday morning, I can assure you. I suppose I should have written "tribology", but I was thinking about how grease moves out of the way.
So, top teams not interested in lubricants or bearing friction losses. Surprising, considering that Team Sky stock stems in 1mm steps. Good opportunity for someone.

That's different...

AFAIK all top teams including Sky use fairly standard components, as supplied by Shimano, Sram etc... they might test them

There is an interest in minimising friction on the track, where the difference between a win and a loss can be in the order of tenths or even cents of a second.

On the road, such small margins can only be appreciated in a photofinish sprint, where you look at centimeters and therefore cents of a second. Problem is there are far bigger factors that influence those centimeters, like at which point the sprinter gets exposed to the wind, or which line he choses for the sprint and how clean that line turns out to be.

Such close wins (or losses) are pretty much a lottery and having better bearings is unlikely to increase the number of wins statistically

Joshgav

I got a new set of Shimano pedals and was surprised at how sticky the spindles seemed. Reckon there's a bedding in period where they loosen up.

imafatman

I suspect pedals need to warm up before they spin free, thinking they probably have some pretty thick grease in there.

pbassred

having better bearings is unlikely to increase the number of wins statistically

Seriously though, you'll have it if it was free? If it gave you a wheel length over 40Km? I see people talk about ceramic wheel bearings and ceramic BB bearings. Well, the pedals turn around the same amount of times, and there are 2 of them.

Pedal/pedal axle
Crank axle/bottom bracket
Chainring/chain
Chain links
Chain/rear sprocket
Derailleur jockey wheels
Wheel axle/frame
Tyre deformation
Tyre/road

all of these thing are studied in minute detail (except jockey wheels - thank you) even aerodynamic shoes, but not the first point in the power train.

Like I say, It doesn't matter to me personally, but as an engineer, I just think its odd.

sungod

when new pedals are packed with grease, some will squish out, they'll ease a bit

when friction facts tested pedals the spread most/least efficient was c. 1.2 watts, however most of that was an outlier, the rest were well below 0.5w (you can find this as 'public' info on their site, the details are in the paid-for test report, no i did not buy it!)

ugo.santalucia

pbassred wrote:

Seriously though, you'll have it if it was free? If it gave you a wheel length over 40Km?

I don't think anyone would be interested in a wheel over 40 km... not even someone attempting the hour record. They probably give you more than that... maybe 4 metres over 40 km or so, which could be of interest to someone doing the hour record.

The downside of looser pedals or bearing in general is that typically they last less. Tight seals and thick grease are there to prevent damage

crankycrank

Most parts with seals including pedals will be a little tight when new. They loosen up with time as well as expel excessive grease.