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Antisquat & waste of energy

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Antisquat & waste of energy
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Posted: Aug 7, 2019 at 16:11 Quote
So, pedal bob is not good, sure, but, I wonder, doesn’t antisquat eat a part of your energy too ? Probably less than pedal bob, but some anyway ?

I mean, look at the Commencal Supreme DH with high pivot.
When it came out last year (or previous year) the high pivot cog (HPC) was concentric to the pivot.
They also released the Supreme SX, which was a short lived big enduro bike with the supreme DH kinematic.

Quickly, Commencal started trying some different position of the HPC, for a bit more antisquat IIRC.
And barely (not Barelli, hu) one year after its release the SX was discontinued.

Well, my point is not to talk about the SX, though there’s probably a reason if it got shelved (too bad it looked like a beast of a bike), but about the concentric pivot and that’s why I talk about the Supreme kinematic :

Because with the same plateforme (Supreme DH) you either have pedal bob or antisquat by just offsetting the HPC by a couple centimeter, so it's more scientifically sound as the only thing that changes is the HPC position, not the main pivot.
So basically you have a bike with pedal bob (=some of the rider energy getting wasted as heat dissipated by the shock) which turns into effective bike with antisquat by just moving the HPC.

But, in physics, nothing is « created » out of thin air, everything is transformed, right ?

So, if there's a force pushing the bike down and wasting energy as heat with pedal bob, antisquat is not magic and requires some energy to counter that force by tightening the chain and pulling on the suspension, right ?

So, instead of wasting energy as heat because of pedal bob, isn’t the same amount of energy wasted as heat right in the rider’s legs by a pedaling motion made harder because of the antisquat process ?

Well, I guess not, because if it were the case the whole antisquat thing would be a scam going on for years, but then where’s the difference ?

Does antisquat acts as some kind of « locking » mecanism, and, while you could say that the first pedal stroke after each sensible bump will indeed waste a bit of energy there won’t be anymore waste as soon as the chain is tight/suspension locked again and for as long as it keeps tight/locked ? Contrary to pedal bob which will waste energy at each pedal stroke ?

Or does antisquat use a bit of the rider’s energy to keep the chain tightened at each pedal stroke, but still not as much as pedal bob ?

I'm being a bit pernickety there but I want to get it right lol

O+
Posted: Apr 26, 2020 at 10:23 Quote
Wow, has nobody answered this question?! I was googling the exact same question and when I saw this in the search results I thought for sure I was going to get some kind of an answer, but nothing?

Here's the thing, my understanding is that anti-squat is actually countering movement caused by forward acceleration, meaning the movement it restricts has nothing to do with wasted pedal forces. If my understanding is correct, your question is even more important because it might be that anti-squat is wasting pedal forces combating something totally unrelated to efficiency.

Posted: Apr 26, 2020 at 12:07 Quote
If I have remembered correctly, the anti-squat uses the leverage of the chain from the rear triangle to front pivot. This is then supposed to counteract the bob force as you pedal heavily and the rear tries to dip down. In the dim and distant past the shock was often driven from both ends as well.

Now the fact that you are using the force in the chain to counteract the squat movement, it must use some energy but, it is all about efficiency. The amount of energy lost in counteracting the squat movement by using the chain should be significantly less than absorbing the same movement into the shock. The latter also simply converts the energy into heat ( as you surmised) but the former stops the shock from having to accommodate the additional rear movement due to the pedalling effort.

O+
Posted: Apr 26, 2020 at 18:10 Quote
To me it isn't at all clear that either the weight shift caused by forward acceleration (squat) or the bouncing movement from my poor pedaling technique (bob) have anything at all to do with energy that could otherwise go towards moving the bike forward. I mean, on a hardtail, squat is still happening, it's just harder to sense. On a hardtail, instead of visible suspension movement, squat is periodic weighting and un-weighting of the rear tire, no? Why would stealing energy from chain tension to resist rearward weight shift make you go faster with less effort then just ignoring it? Same thing with pedal bob. My crappy, bouncy pedaling still causes periodic bobbing on a fully-rigid road bike, only instead of visible suspension movement it's absorbed by my body and only measurable as frame flex and slight cyclic weighting and un-weighting of the tires, no? Why should I assume any of that force is magically routed through the chain to the rear wheel?

I'm 100% sure my complete lack of engineering knowledge is causing me to miss something obvious here, but it just seems to be we might be taking about anti-squat making things feel efficient instead actually being efficient.

Posted: Apr 28, 2020 at 15:42 Quote
I just noticed my solar-system-long question has been posted on the front page lol

It's late here so I'm not gonna think too much, I'll come back after a good sleep, I just want to point out that in the initial post I talk about the Supreme SX as a concentric high pivot but it isn't, the high idler is a bit lower and rearward than the main pivot. (So I don't know why it got shelved so quickly, I've seen comments saying that high pivot may be great for DH but not for freeride where you supposedly need a more playfull, more "poppy" bike).

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