Enduro/AM - The Weight Game

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Enduro/AM - The Weight Game
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Posted: Nov 19, 2019 at 0:00 Quote
Arnoodles wrote:
Out of curiosity, have you ridden a pole or looked at the kinematics? Some of their early models in particular had some odd kinematics ideas if I remember right. Any thoughts on those vs new ones?

Unfortunately, I haven't ridden one. Very keen to. I can only refer to my simulations, though I find the simulations correlate well with the ride experiences on other bikes.

Note: My Evolink simulations are from calendar year 2017; if there have been updates to the kinematics since then, I haven't modeled these.

Motion ratio

The Evolink starts with a moderately rising motion ratio and ends with a sharp drop. This was a common curve shape when designers were trying to compensate for the rising rate of air shocks. The Machine and Stamina are both quite progressive, with just a little flattening of the curves at the end. This is in line with Mike Levy's comments that the Stamina felt supple off the top and very supportive near full bump.

Pedaling anti-squat

On all Pole models, the pedaling anti-squat drops quickly as they move through their travel. This is a popular technique to reduce pedal kickback. The difference is that the Evolink starts low and ends really low, while the anti-squat curves of the Machine and Stamina are typical of current bikes.

Posted: Nov 19, 2019 at 0:02 Quote
R-M-R wrote:
Arnoodles wrote:
Out of curiosity, have you ridden a pole or looked at the kinematics? Some of their early models in particular had some odd kinematics ideas if I remember right. Any thoughts on those vs new ones?

Unfortunately, I haven't ridden one. Very keen to. I can only refer to my simulations, though I find the simulations correlate well with the ride experiences on other bikes.

Note: My Evolink simulations are from calendar year 2017; if there have been updates to the kinematics since then, I haven't modeled these.

Motion ratio

The Evolink starts with a moderately rising motion ratio and ends with a sharp drop. This was a common curve shape when designers were trying to compensate for the rising rate of air shocks. The Machine and Stamina are both quite progressive, with just a little flattening of the curves at the end. This is in line with Mike Levy's comments that the Stamina felt supple off the top and very supportive near full bump.

Pedaling anti-squat

On all Pole models, the pedaling anti-squat drops quickly as they move through their travel. This is a popular technique to reduce pedal kickback. The difference is that the Evolink starts low and ends really low, while the anti-squat curves of the Machine and Stamina are typical of current bikes.
Fair enough. Am I correct in remembering you prefer higher anti squat? How does the efficiency weigh against suspension performance while pedaling?

Posted: Nov 19, 2019 at 0:21 Quote
R-M-R wrote:
It's not backwards. Perhaps I could've written it more clearly.

Imagine a person seeks to put out low power - let's say 50 watts, for example. If that's the ideal output for a given scenario, then it's best to pedal slowly. This isn't the cadence at which the rider can produce maximum power, but the metabolic cost of simply turning their legs would be unnecessarily high at higher cadence, so it's best to spin slowly. As the rider desires to put out more power, the rider's optimal cadence will increase - to some limit, of course, which is determined by physiology and duration.

It's too general to say "most riders are better off riding at 200 watts and 80 rpm than they would be at 150 watts and 100 rpm". The statement is almost certainly true for an athlete that can easily sustain 200 W. If a rider struggles to maintain 200 W, such that it's essentially a threshold output, then 150 W at almost any reasonable cadence will be easier for that person. This illustrates the more subtle point that an athlete may be able to sustain a less efficient cadence for longer, which makes for a faster overall ride.

I've also read about the reduced blood flow at extreme cadence. It depends on the individual and the situation. Sprints always involve high cadence because that's the optimum for the situation. Similarly, soft-pedaling at the back of a pack in a headwind is most efficient at low cadence. For most people, a one-hour time trial will favour the sub-100 cadence you've described. It varies by rider, by power output, and by duration required.
While your first point makes sense after you restating it, you seem to be ignoring the reality that the window of that "to some limit" is very narrow for the huge majority of riders; which is the 70-90 rpm range I've mentioned. Very few people can produce a higher threshold output above that range than they can within it and fewer still can produce higher power endurance efforts over extended periods above that level... which was the point of my pedal 25% softer but 25% faster example more than the specified wattage. Whether you're talking about a one hour TT or a 5 hour stage, most humans simply don't have the type of physiology that lends itself to such rapid spinning while maintaining any degree of efficiency in their overall energy output. Sprints really aren't reflective of the discussion as, by their nature, they eschew efficiency in favor of extremely high power over extremely short distance... that's like discussing fuel efficiency on the drag strip.

Posted: Nov 19, 2019 at 0:31 Quote
Arnoodles wrote:
Fair enough. Am I correct in remembering you prefer higher anti squat? How does the efficiency weigh against suspension performance while pedaling?

Yes, that's correct. Maybe I should be more general and say I've found very high anti-squat is necessary to keep the bike as stable as I want it to be. There's virtue in a bike with less kickback and many people prefer the feel.

Reducing pedal bob is actually quite complicated. The primary cause of squat is weight transfer due to acceleration, but there's a secondary cause from the inertial effects of the rider's leg and torso movement. The unexpected result is there's a zone of moderate anti-squat that actually feels less stable than higher and lower anti-squat.

I haven't been able to determine whether this region of low anti-squat that feels stable is more or less efficient than the "uncanny valley" of intermediate anti-squat and I don't think I'll ever be confident in the test results, as there are too many variables to easily pick out a subtle result. My current recommendation is high anti-squat for efficiency and low anti-squat for riders who strongly prefer smooth pedaling; intermediate anti-squat may be an unhappy medium.

The negative effects of anti-squat on suspension performance are minimal. I notice it only in the lowest ratios, when efficiency is more important than suspension. As speed increases and I use a higher ratio, bump forces overwhelm chain tension and kickback decreases, so the negative effects disappear.

The main problem with high anti-squat is the pedal kickback on rough terrain at low speed - the first couple of sprockets. If my legs are already tired and full of lactic acid, the "stalling" feeling of kickback doesn't feel good. Lower kickback may feel better, but it's also possible I would be even more tired if I had been pedaling a squishy bike for the whole ride until I encountered that slow, rough section.

Posted: Nov 19, 2019 at 0:35 Quote
badbadleroybrown wrote:
While your first point makes sense after you restating it, you seem to be ignoring the reality that the window of that "to some limit" is very narrow for the huge majority of riders; which is the 70-90 rpm range I've mentioned. Very few people can produce a higher threshold output above that range than they can within it and fewer still can produce higher power endurance efforts over extended periods above that level... which was the point of my pedal 25% softer but 25% faster example more than the specified wattage. Whether you're talking about a one hour TT or a 5 hour stage, most humans simply don't have the type of physiology that lends itself to such rapid spinning while maintaining any degree of efficiency in their overall energy output. Sprints really aren't reflective of the discussion as, by their nature, they eschew efficiency in favor of extremely high power over extremely short distance... that's like discussing fuel efficiency on the drag strip.

I didn't say you were wrong, just expanding the statements by adding scope and nuance.

Posted: Nov 19, 2019 at 0:47 Quote
badbadleroybrown wrote:
Fair enough Beer

Salute

Posted: Nov 19, 2019 at 2:59 Quote
R-M-R wrote:
Arnoodles wrote:
Fair enough. Am I correct in remembering you prefer higher anti squat? How does the efficiency weigh against suspension performance while pedaling?

Yes, that's correct. Maybe I should be more general and say I've found very high anti-squat is necessary to keep the bike as stable as I want it to be. There's virtue in a bike with less kickback and many people prefer the feel.

Reducing pedal bob is actually quite complicated. The primary cause of squat is weight transfer due to acceleration, but there's a secondary cause from the inertial effects of the rider's leg and torso movement. The unexpected result is there's a zone of moderate anti-squat that actually feels less stable than higher and lower anti-squat.

I haven't been able to determine whether this region of low anti-squat that feels stable is more or less efficient than the "uncanny valley" of intermediate anti-squat and I don't think I'll ever be confident in the test results, as there are too many variables to easily pick out a subtle result. My current recommendation is high anti-squat for efficiency and low anti-squat for riders who strongly prefer smooth pedaling; intermediate anti-squat may be an unhappy medium.

The negative effects of anti-squat on suspension performance are minimal. I notice it only in the lowest ratios, when efficiency is more important than suspension. As speed increases and I use a higher ratio, bump forces overwhelm chain tension and kickback decreases, so the negative effects disappear.

The main problem with high anti-squat is the pedal kickback on rough terrain at low speed - the first couple of sprockets. If my legs are already tired and full of lactic acid, the "stalling" feeling of kickback doesn't feel good. Lower kickback may feel better, but it's also possible I would be even more tired if I had been pedaling a squishy bike for the whole ride until I encountered that slow, rough section.
That makes a lot of sense actually and I never really thought about the unhappy medium thing but I can see it being a thing.

One hypothesis for this might be that some of the bob at medium antisquat might come from the dead point in the pedal stroke allowing the bike to "settle" back down. The antisquat being more effectively applied during the better powered part of the stroke would then pull the bike back up. With a higher antisquat the bike is held up better at the dead point since less pedaling torque is required to do so. With lower antisquat it never gets "held up high" in the first place to drop back down from.

Of course this bobbing from the dead point could still apply at a higher antisquat to an extent, but maybe there's a threshold below which the antisquat forces at the dead point torque are too low to have much effect. This way any antisquat value above this threshold by a reasonable margin would greatly reduce this unhappy medium effect.

Is this coherent enough? lol Is there any sense in that hypothesis at all or is that complete nonsense?

Also, do you have a rough range of antisquat percentage where you think this unhappy medium might materialize? Might be worth considering for my next footcycle.

Posted: Nov 19, 2019 at 3:16 Quote
Arnoodles wrote:
That makes a lot of sense actually and I never really thought about the unhappy medium thing but I can see it being a thing.

One hypothesis for this might be that some of the bob at medium antisquat might come from the dead point in the pedal stroke allowing the bike to "settle" back down. The antisquat being more effectively applied during the better powered part of the stroke would then pull the bike back up. With a higher antisquat the bike is held up better at the dead point since less pedaling torque is required to do so. With lower antisquat it never gets "held up high" in the first place to drop back down from.

Of course this bobbing from the dead point could still apply at a higher antisquat to an extent, but maybe there's a threshold below which the antisquat forces at the dead point torque are too low to have much effect. This way any antisquat value above this threshold by a reasonable margin would greatly reduce this unhappy medium effect.

Is this coherent enough? lol Is there any sense in that hypothesis at all or is that complete nonsense?

Also, do you have a rough range of antisquat percentage where you think this unhappy medium might materialize? Might be worth considering for my next footcycle.

This puts me in a difficult situation. I enjoy sharing knowledge and helping the community, as you can tell from the huge amount of typing I do - or maybe I just like standing on my e-soapbox! I'll let you judge that. Anyway, answering your questions would require specific insights and numbers that have taken me hundreds of hours to discover. I consider it proprietary information that can be provided to clients - or maybe my own project, which I'm currently considering. It would be fun to discuss and I would surely do so if we were chatting during a ride, but I'd prefer to not put it in the public domain at this time.

Speaking in general terms:

Chain tension only resists squat in varying degrees; it doesn't fully overcome it and cause the bike to rise. There were a few bikes that had this problem during the "Cambrian explosion" of suspension designs - made worse by 22T chainrings - but it's no longer an issue.

When anti-squat from chain tension perfectly balances squat from acceleration, it doesn't matter how much force is applied at the cranks because the forces are balanced.

Posted: Nov 19, 2019 at 4:29 Quote
R-M-R wrote:
MikeAzBS wrote:
What kind of manufacturing company allows prototype components to migrate into production? That's a major red flag and shouldn't be possible. Design and review components should always be CLEARLY labeled and segregated/confined to an isolated workspace. Imagine a snapped head tube during H2F. Not good. I'm not convinced it wasnt sent on purpose. Prototype's get marked up for future NDT if they are doing things the right way.

Yeah, I don't believe it, either. I insist on inspecting a bike myself before sending it out. Although it's not entirely fair to give extra QC to a test bike, relative to what a consumer would get, it's necessary when so much is at stake. I don't believe any company would send a bike to a major site without looking it over.

My guess is this was either a sneaky trick to save some weight or really bad QC due to poor marking and checking procedures.

Do they clear anodize their aluminum? I only ask because I cant imagine they would pay to ano a prototype. Any half decent machinest or assembly tech would spot that from across the room. Even if they use standard 8625 type 2, it wouldn't even be close. Especially after handling it for a few minutes. I guess they could do it in house.

Posted: Nov 19, 2019 at 4:38 Quote
R-M-R wrote:
Arnoodles wrote:
That makes a lot of sense actually and I never really thought about the unhappy medium thing but I can see it being a thing.

One hypothesis for this might be that some of the bob at medium antisquat might come from the dead point in the pedal stroke allowing the bike to "settle" back down. The antisquat being more effectively applied during the better powered part of the stroke would then pull the bike back up. With a higher antisquat the bike is held up better at the dead point since less pedaling torque is required to do so. With lower antisquat it never gets "held up high" in the first place to drop back down from.

Of course this bobbing from the dead point could still apply at a higher antisquat to an extent, but maybe there's a threshold below which the antisquat forces at the dead point torque are too low to have much effect. This way any antisquat value above this threshold by a reasonable margin would greatly reduce this unhappy medium effect.

Is this coherent enough? lol Is there any sense in that hypothesis at all or is that complete nonsense?

Also, do you have a rough range of antisquat percentage where you think this unhappy medium might materialize? Might be worth considering for my next footcycle.

This puts me in a difficult situation. I enjoy sharing knowledge and helping the community, as you can tell from the huge amount of typing I do - or maybe I just like standing on my e-soapbox! I'll let you judge that. Anyway, answering your questions would require specific insights and numbers that have taken me hundreds of hours to discover. I consider it proprietary information that can be provided to clients - or maybe my own project, which I'm currently considering. It would be fun to discuss and I would surely do so if we were chatting during a ride, but I'd prefer to not put it in the public domain at this time.

Speaking in general terms:

Chain tension only resists squat in varying degrees; it doesn't fully overcome it and cause the bike to rise. There were a few bikes that had this problem during the "Cambrian explosion" of suspension designs - made worse by 22T chainrings - but it's no longer an issue.

When anti-squat from chain tension perfectly balances squat from acceleration, it doesn't matter how much force is applied at the cranks because the forces are balanced.
That's fair enough. Thanks anyway for the responses. As they say, never do anything you're good at for free. Salute

Posted: Nov 19, 2019 at 7:03 Quote
R-M-R wrote:

The main problem with high anti-squat is the pedal kickback on rough terrain at low speed - the first couple of sprockets. If my legs are already tired and full of lactic acid, the "stalling" feeling of kickback doesn't feel good. Lower kickback may feel better, but it's also possible I would be even more tired if I had been pedaling a squishy bike for the whole ride until I encountered that slow, rough section.

I couldn't have said it better myself... Low pedal kickback so over played.. My bike has quite a bit of it, and many long day in the saddle experienced riders have ridden my bike, and afterwards said, "what pedal kickback"... One of my close buddies did a one day 40 mile 12,000' climbing day on it, at 33lbs, coil shock with no lockout, and said he'd do it again no problem. I think the high anti-squat is SO much more important than worrying about pedal kickback, if needing to choose one or the other.

Posted: Nov 19, 2019 at 7:20 Quote
Circe wrote:
My best bet is they sent an early production bike with a rev one swing arm. They called it “XC” because you know....

Lots of arm chair engineers in the review making claims about poor rear swing arm design. RMR, do you have any thoughts on that aspect?

R-M-R gave the proper technical detailed failure reason already, but if it was not broken down elsewhere in more simple terms...

Those struts that buckled are the only parts connecting the upper and lower stays in the rear triangle.The shock being driven off the upper stays/upper linkage means that the struts are in compression while actuating the suspension. Thin cross section material does fine in tension, but not compression. Think how a single spoke can take a lot of force before snapping when pulling, but it buckles with close to zero force under compression.... If the shock was driven off the lower linkage, even the XC struts would probably have been plenty strong for DH riding even!

Posted: Nov 19, 2019 at 7:25 Quote
thuren wrote:
R-M-R wrote:

The main problem with high anti-squat is the pedal kickback on rough terrain at low speed - the first couple of sprockets. If my legs are already tired and full of lactic acid, the "stalling" feeling of kickback doesn't feel good. Lower kickback may feel better, but it's also possible I would be even more tired if I had been pedaling a squishy bike for the whole ride until I encountered that slow, rough section.

I couldn't have said it better myself... Low pedal kickback so over played.. My bike has quite a bit of it, and many long day in the saddle experienced riders have ridden my bike, and afterwards said, "what pedal kickback"... One of my close buddies did a one day 40 mile 12,000' climbing day on it, at 33lbs, coil shock with no lockout, and said he'd do it again no problem. I think the high anti-squat is SO much more important than worrying about pedal kickback, if needing to choose one or the other.

I dont notice the kick back one bit.

Posted: Nov 19, 2019 at 7:34 Quote
Tsoxbhk wrote:

I dont notice the kick back one bit.


To be totally fair Tory I notice it, but I have to zone everything else out and really focus in on it go do so haha!


 
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