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[Kernow]

Just came across this , amazing to see the stresses a bike and its suspension goes through in slow motion

 

[Shinn]

Says a lot about todays materials and engineering. Looks like fun too.

 

[urastus]

Looks like a tendency to under inflate rear tyres

 

[Kernow]

Looks like a tendency to under inflate rear tyres

I agree , looks Like suspension and Tyres have all been a bit under inflated to get the most extreme compression for the pics .

 

[Zimmerframe]

In anticipation for bambam's arrival and disappointment that the thread wasn't what he imagined ..

 

[Tim1023]

In anticipation for bambam's arrival and disappointment that the thread wasn't what he imagined ..

View attachment 50395

That's one helluva builder's cleavage!

I wonder if there is any connection between this and the "What's this hole for?" thread

 

[Zimmerframe]

Just came across this , amazing to see the stresses a bike and its suspension goes through in slow motion

It's actually interesting to see how the different bikes geometries and wheel bases change as they go through the suspension range.

And REALLY interesting to see the interaction between suspension/tyres/suspension. On a lot of the clips you see the tyre compress, then the suspension compressing, then the tyre re-bounds increasing the speed of suspension compression - so the suspension compression slows due to damping. The tyre then compresses again and the suspension then continues it's compression. It's not a linear movement through the compression stroke due to the tyre and suspension both acting under compression, but the tyre having no rebound control.

 

[maynard]

On

It's actually interesting to see how the different bikes geometries and wheel bases change as they go through the suspension range.

And REALLY interesting to see the interaction between suspension/tyres/suspension. On a lot of the clips you see the tyre compress, then the suspension compressing, then the tyre re-bounds increasing the speed of suspension compression - so the suspension compression slows due to damping. The tyre then compresses again and the suspension then continues it's compression. It's not a linear movement through the compression stroke due to the tyre and suspension both acting under compression, but the tyre having no rebound control.

Uhhhh my head hurts WTF are you talking about zim . Ok that's enough intelligence like talking stuff now . Its a bike going bouncy ok .

 

[slippery pete]

@Zimmerframe has got it spot on.

?... I know.

A lot of that will be underinflated tyres. If the tyre resonant frequency and the spring damper resonant frequency are close to the same, the energy will resonate between them for sure which is what you're seeing here Undamped tyre energy transferring into the spring/damper is exactly how tyre energy gets dissipated. It isn't necessary for the tyre to have a damper. However, you get more damping of tyre energy if you can avoid resonance between the two... as long as you're not compromising other parameters... and remembering that the rider is a rubbery collection of flesh and bone that eludes accurate scientific description.

 

[Shinn]

In anticipation for bambam's arrival and disappointment that the thread wasn't what he imagined ..

View attachment 50395

Horrible saddle position for a ride around town.

 

[Kernow]

Would be good to see a comparison using tyres with inserts . I noticed quite a different feel with inserts which was more damping from the tyre but never put a connection to how that could react with suspension ,
thinking about with an insert in the tyre the compression and rebound from the tyre is more controlled and it’s damped both in compression and rebound by the insert with less effect on suspension . Depends on different inserts I guess but Iam thinking the ones that fill the tyre rather than just rim space will be more effective .

 

[Zimmerframe]

the rider is a rubbery collection of flesh and bone that eludes accurate scientific description

You should start a special thread with that. It only needs one post. "Description of the average e-biker !"

 

[Zimmerframe]

@Zimmerframe has got it spot on.

?... I know.

A lot of that will be underinflated tyres. If the tyre resonant frequency and the spring damper resonant frequency are close to the same, the energy will resonate between them for sure which is what you're seeing here Undamped tyre energy transferring into the spring/damper is exactly how tyre energy gets dissipated. It isn't necessary for the tyre to have a damper. However, you get more damping of tyre energy if you can avoid resonance between the two... as long as you're not compromising other parameters... and remembering that the rider is a rubbery collection of flesh and bone that eludes accurate scientific description.

I know in the past I've been guilty of sometimes running tyre pressures too low thinking it gives me better small bump compliance. Earlier last year I had a couple of DH sections where I would actually lose focus (physically) from eyeshock/wobble/vibration. Eventually sorted with compression/rebound and pressure changes - but my first instinct was oooh, less tyre pressure - wrong !

For me it's a good demonstration of how running too low a tyre pressure can really mess up your bikes handling/suspension response. €1000's of euro's of suspension with countless hours spent setting up how it will respond, only for an e-muppet with a €50-€100 tyre to be run at a pressure which throws a completely random spring element into the equation.

And .. just for @maynard so we keep this thread interesting for everyone ..

 

[steve_sordy]

I could not take my eyes from how far the chain was moving about! In some it hit the floor, in others I am astonished that the chain stayed on the ring. Most of the mechs were really lively too. How many of those mechs had a clutch?

 

[RickBullotta]

"Huck to flat". Avoid.

 

[Zimmerframe]

 

[Zimmerframe]

Some other bikes .. and a bit of intro on the test ..

 

[urastus]

I could not take my eyes from how far the chain was moving about! In some it hit the floor, in others I am astonished that the chain stayed on the ring. Most of the mechs were really lively too. How many of those mechs had a clutch?

I wouldn't be surprised if they were all clutched. I always see that in still shots too.

On my older analogue bikes (2 x 10) they are not clutched, but I have chain keepers which do a better job where it is needed. One of the downsides of 1x systems is that these are no longer viable with the existing designs. It probably wouldn't be hard to design one that does work with 1x systems.

 

[Mikerb]

I think a lot of the video is done purely for effect. Most are 2 wheel landing...you dont have to land flat even if the landing is flat. The tyres are clearly underinflated and the rider does little to absorb the landing. Even the forks look to be at a low pressure let alone the shock.

 

[Gary]

Your ability to describe the entire point of the video and yet still not understand it is really quite a gift Mike

 

[Mikerb]

Yes I understand the "point". As stated..."viewer pleasure". In other words completely meaningless in terms of function which, predictably, is what people respond and comment about.

 

[Gary]

meaningless in terms of function

Really?


?

 

[Mikerb]

Yes!! All suspension set at the biggest Sag setting..30%...regardless of actual rider weight or frame/suspension design, derailleur in the highest gear/slackest chain......landing 2 wheels flat....no attempt to absorb the landing.....dubious claim of 30 psi plus tyre pressures. So just done to emphasise effect for the benefit of a slow mo camera and video views. Fine for a bit of fun, but as I said, it is predictable that many will interpret it as a technical review.

 

[Gary]

wow.

You really have missed the point entirely in terms of function haven't you?
So you somehow don't believe extremely similar forces go through suspension and frame components under normal riding senarios with a half decent rider onboard?
if you want to see the exact same thing in a non "staged" setting watch any of the Vital mtb G-out project videos from the racing season. Which incidentally Pinkbike clearly got their inspiration from.

It's simply an interesting well shot video that clearly shows component and structure flex and suspension binding because of exterior force.
Contrary to your belief the harshest landings/forces actually do happen when the bike is in the smallest cassette sprockets and riders do run tyre pressure that are bordering the limit of support in the quest for ultimate grip.
30psi is actually below the limit of good support in a lot of condition for a rear tyre for me.

I honestly didn't have you down as so naive. but every day's a school day. eh?

Don't lose any sleep over it though

 

[Mikerb]

"but every day's a school day. eh?"
Seems it is for you Gary. Here is today's lesson........the video has a target audience, and that is not pro downhill riders....or extreme amateurs...neither of whom need instruction from these guys. I know you wish it were not the case, but the vast majority on this forum are every day MTBers, some pretty proficient, but some just setting out. The video would be a great deal more useful to most if it was prefixed with....."this is what could happen if you fail to set you bike up properly, ride off a fair sized drop to a flat landing and land on 2 wheels at the same time without absorbing the load on your bike ....chances are you could damage your suspension, tyres, rims......and body!".

ps...no sleep lost mate. I way to old and experienced to dwell on words on a forum.

 

[Gary]

I personally do know professional DH riders who have watched this video. So I'm not sure what point you are trying to make there,
You don't know anything about what I "wish" so please don't speculate wildly. The vast majority of ALL cyclists are just every day folk with jobs, families and bills to pay and a common interest. I've been biking all my life and ridden with pretty much every type of rider from complete beginner/non cyclist/kids to full time professionals and still do.

The video posted is smply an interesting video, Stop overthinking it and trying to second guess other peoples reaction to it.

It doesn't need any prefix of the sort. it actually is what happens to your bike while you ride it. Dude. when younger I did 15ft drops and 50ft jumps on hardtails with 100mm of travel, 28mm stanchions and QR wheels often not landing the smoothest. I'd absloutely love to have had high quality slowmo footage of that to look back on today. But just looking back in my mind gives me tremendous confidence in todays far superior bikes and components. We're spoilt for choice really and most of those beginners you mention are able to buy suspension, frames and components vastly more capable than were even dreamed of back in the early days. When riders were also doing big drops, jumps and riding fast over technical terrain. If these videos are interpreted by anyone as a "technical review" they simply have very little understanding of what they are watching and are (like you) overthinking it massively.

 

[Kernow]

Yes!! All suspension set at the biggest Sag setting..30%...regardless of actual rider weight or frame/suspension design, derailleur in the highest gear/slackest chain......landing 2 wheels flat....no attempt to absorb the landing.....dubious claim of 30 psi plus tyre pressures. So just done to emphasise effect for the benefit of a slow mo camera and video views. Fine for a bit of fun, but as I said, it is predictable that many will interpret it as a technical review.

Mike you seem to have misunderstood this in every way , watch it again especially the info on set up sag setting etc they Are talking about 30%sag with rider aboard which is about normal for most of us I’ve never heard of a static (unloaded ) sag setting used on a bicycle

and then the landings . The slow mo does indeed at first look make the rider appear to be not absorbing the shock but they really are , otherwise there Would be injuries . It just illustrates how far behind the first impact our body reaction is , I had to watch that twice .

flat landing , well almost flat on some onto a Fiat surface , how else would you want them to land, looking at the set up of the jump and the bikes trajectory , even if it wasn’t a test there aren’t many who could turn that landing into a manual or stoppey ?
they are in smaller cogs faster gears because that reflects the speed they needed to pedal at on the run up , jumping off Ramps requires a bit of speed remember they are enduro or trail bikes not downhill bikes so have wide spread of gears longer chains softer lighter Tyres and suspension

 

[Tim1023]

That's one helluva builder's cleavage!

I wonder if there is any connection between this and the "What's this hole for?" thread

There's another thread that has just reactivated that would seem to fit here: Breathable waterproof shorts?

 

[whiterabbit]

Looks like a tendency to under inflate rear tyres

man, but the grip is SO good when doing that..

 

[kendo]

Just came across this , amazing to see the stresses a bike and its suspension goes through in slow motion

Should be some criminal charges made against those riders wearing lycra....no excuse.?