[Frankenthe3rd]

Extend your forks completely and measure from the bottom of the fork tube to the top of the seal. Then check against the listed Max fork travel in the manual. That'll let you know where bottom is.

 

[Frankenthe3rd]

Well, as I said Zip-tie in front fork should be banned, because it causes much more problems than bottoming out...

Incorrect: Zip tie actually gives you two bits of info: A) if it actually bottomed out; or B) How much shock you actually used since the last time you changed it - which is it's only purpose. And it does that well - and cheaply. ANYTHING after that belongs in the purview of the suspension tech with the proper tools and training, and the rider's individual skill level.

But to each his own. I'll keep using a ziptie. There is NO situation where bottoming out the suspension while riding is a good thing. EVER.

Yes, front suspension should always use 100% of its suspension travel, that 100% includes also bottoming out. In ideal situation that bottoming out happens every time when you hit your brake mark and start braking. And depending on how much your bikes front end can carry load (weight shifting + braking force), it gives you a limit how much your maximum brake force can be when you start braking.
If you are using too much braking force compaired to the front end load handling capacity, front end will bottom out too much/ too long and front wheel starts to act like a snake, and goes from side to side.

Alright, I'll bite, seeing as Dave Moss was mentioned earlier. For the record, I'd not be surprised if he had worked on more bikes than day's you've been alive...

Firstly, using a zip-tie is a tried and tested method of determining how much fork travel you are using. To suggest that it be 'banned' because some people may interpret that incorrectly is dangerous advice.

Secondly, for someone that has measured where bottom is on their fork travel, and is using a zip-tie, they will very easily be able to see if they have reached bottom and "THEREFORE" need to adjust their spring / compression or riding style to ensure that it is working optimally.... which leads me onto...

Thirdly, front suspension that is bottoming out is not working correctly! If you have bottomed the forks at any point then the suspension is not doing it's job and all forces are being pushed through the tire - this is a recipe for a crash. Even if you have only bottomed the forks at a single point on the track, then it is likely to be the hardest braking zone of the track, which means you need the suspension to be working. If the corner requires trail braking and you haven't removed enough braking pressure from the fork bottoming out, expect to crash.

Fourth, it is incorrect to be using 100% of your fork travel "every time you hit your brake mark and start braking". Without even discussing the issue of weight transfer, cornering geometry and the tires ability to cope with doing the suspension work, what happens when you suddenly gain a bit of speed and need to brake harder???

And lastly... can one of the mods here change speedfinn's name to Zoo2, just so everyone else has some kind of heads-up?....

 

[Frankenthe3rd]

Sounds like you're trying to get us to sort out your own suspension issues..

Let me know when you find some wsbk or MotoGP with the riders fully bottoming.

You keep riding with your 100% use of the fork travel mate...

 

[Frankenthe3rd]

Wow.



Just wow.





Brilliant!

People wonder why all of the intelligent people tend to leave forums. Threads like this push us over the edge


Sent from my iPhone using Tapatalk

Someone else needs to take the reins on this one....... Anyone?

 

[Frankenthe3rd]

Sounds like you're trying to get us to sort out your own suspension issues..
Let me know when you find some wsbk or MotoGP with the riders fully bottoming.
You keep riding with your 100% use of the fork travel mate...

Well, the only issue/ problem is that you do not understand suspension basics regarding a track only bike. That is why you can not answer to a simple question about a real life situation.

And that is why you do not understand that any fast bike/ rider is always using 100% of the fork travel. And that 100% includes also bottoming out.

The real problem is that your suspension God has told you that bottoming out is not normal behaviour of suspension, bottoming out is dangerous, and you will crash if front end bottoms out. And you believe him, and your faith is very strong. That is why you do not understand that your God has given you bad info.

If you think about some random wsbk or MotoGP bike; why would they not be using 100% of the fork travel? Why would they like to loose in lap time because of that?

Alright now I'm convinced you're just trolling.

Please, provide one "credible" piece of information that states that what you're saying is true... Just one...

 

[Frankenthe3rd]

Lateral grip is not needed when the bike is upright. That is why it does not matter if the front end uses 100% of the suspension travel and bottoms out, when you start braking.

And as you can see from the data, that is normal behaviour for track only bikes front end. And you can also see from the data, that everywhere else suspension is not close to bottom out. So when lateral grip is needed, suspension has travel left to react to unexpected bumps.

Take any fast bike/rider; their front end will bottom out a few times per lap/ as you can see from the data.

If they would try to prevent that, they would either have to brake much less, and lose at least a couple of seconds per lap.

Or they would have to stiffen up front end so much, that they would loose too much front end traction, and again they would loose at least a couple of seconds per lap.

That is why Dave Moss 80/20% rules are not a problem for slow riders, or street riders, or for people who do not understand suspension basics.

"Take any fast bike rider, their front end will bottom out a few times per lap"....

Like I said, take the fastest riders from WSBK and MotoGP and try to tell me they're bottoming their forks. You can make huge generalisations but keep in mind that this encompasses all the "fast" riders that still have an incorrect spring or damping in their forks.

"As you can see from the data"....

Well I can't see anything from the 'data'. All you've provided us is some graph with no indication of what is being measured against what, and then you've added your own red line which is meant to mean something, for some fast rider.

You are still yet to provide any credible information to support your idea.

Lets see if you can explain to the folks here how exactly a bike under hard braking that uses 90-95% of it's fork travel will have less grip than a bike that has used 100% of it's travel and has bottomed out?

I have added a graph that provides a clearer picture for our viewers...

 

[Frankenthe3rd]

"Take any fast bike rider, their front end will bottom out a few times per lap"....

Like I said, take the fastest riders from WSBK and MotoGP and try to tell me they're bottoming their forks. You can make huge generalisations but keep in mind that this encompasses all the "fast" riders that still have an incorrect spring or damping in their forks.

"As you can see from the data"....

Well I can't see anything from the 'data'. All you've provided us is some graph with no indication of what is being measured against what, and then you've added your own red line which is meant to mean something, for some fast rider.

You are still yet to provide any credible information to support your idea.

Lets see if you can explain to the folks here how exactly a bike under hard braking that uses 90-95% of it's fork travel will have less grip than a bike that has used 100% of it's travel and has bottomed out?

I have added a graph that provides a clearer picture for our viewers...

As everybody has already noticed, only our own suspension God can give you credible info that your ego approves. He is the only credible source for you, everything else is just blasbhemy in our eyes.

So next time you meet Him, ask Him is the fastest riders from WSBK and MotoGP are bottoming their forks, and how often that occurs per one lap. Do not be suprised if the answer is something totally unexpected/ against your current "truths".

Because you do not understand suspension basics, I also assumed that you do not have any experiense on suspension data logging and analysing. That is why I tried to make the data as simple as possible for you to understand. But no luck...


For other thread readers:
If you have any kind of questions about track only bike front end bottoming out and/or suspension data regarding that, just ask. I'm happy to share the knowledge what I have gained in past ~11 years.

And as I said previously, Dave Moss has some good info and some bad info. Most of hes clients are riding street bikes with stock suspension on road or on track, and that is totally different situation than track only bike. That is why you should always put the info to correct context, and if you do not now suspension basics, it is hard for you to know what would be the correct context.

https://youtu.be/UEqzjKrWhAk

Motegi Circuit... I think these guys are some fairly accomplished riders and it doesn't look like they're bottoming.

 

[Frankenthe3rd]

Zero-budget? Well, in that case it is quite simple: You just need to always keep in mind that when the front end bottoms out at the start of the braking; there is your front ends limit, it can not cope with any stronger stress than that. So, front end might feel a bit weak, but that is the result of the zero-buget.

It does not matter if you hit the brakes hard, or if you slowly increase the squeez; your front end will bottom out, because in either case it has to carry the load you are pushing on top of it.

And it does not matter if you feel that the deceleration is only 70-80% when the front end starts to squirm a little bit. There is the limit.

If you want to get in to the trouble, just think once "I am braking so softly..." ,"How about..." or "Just a little bit..." while riding on the track, and you will try to do something what your bike is not capable to. You have to first change te bikes capability before you can "Just a little bit more..."

So, know the (zero-buget) limit, and drive according to it. It is very easy to forget it.

This thread has now gone officially "FULL RETARD". You never want to go full retard. Only good thing is this is almost as entertaining as reading a zoo post, but people are going to read this **** and actually believe it and are going to get hurt.

I tried... But that is exactly the point. I don't want to see anyone misinformed.

 

[Frankenthe3rd]

Seriously sounds like Shervin

http://blog.motorcycle.com/2010/05/...n-exhaust-and-cutting-holes-in-the-frame/amp/

 

[Frankenthe3rd]

I’m going to buy new springs for forks you think 11.5 will be good?

For your (220lbs) weight 11.5 springs are good. For your current braking ability; too stiff. If you use zip tie, you probably will end up to a situation where you are stairing at the zip tie, which indicates that you are using only a part of the compression travel. The only reasonable cure for that is to consentrate on your driving line, and your speed will increase, and you will brake harder, and you will use more of the compression travel. And I assume that your target is to go faster, so no problems with 11.5 springs.

Usually people mix up spring stiffness and compression damping stiffness. Because right side of the brain feels that front end is stiff, and left side of the brain says that:"Hey! We now have stiffer springs." So, if you feel that front end is too stiff/ does not use 100% travel, and you really must do something just to feel better, then loosen up compression damping. Then front end does not feel so stiff, even though you still have the same "stiff" springs in it.

Also, after service/ front spring change, you will have stiffer oil (when compaired to old oil) in front forks, and also that makes front end feel stiffer. Yet again, compression damping.

If you compaire for example 11.0 and 11.5 springs, the compression travel difference at 1.0G decelration is about 4.4 mm. Thats about the same as zip tie width. Can you notice that difference while braking? Or can you notice 5% difference in spring constant when pumping the font end in pit box? But if you add or decrease compression damping a couple or few clicks, you will definitely notice the difference in front end stiffness, and it does not matter whether you have 11.0 or 11.5 springs.

Pretty sure all these spring rates and maths are irrelevant, it doesn't matter if you use 100% travel so it doesn't matter when you get there - just hit that hydraulic/mechanical bottom as soon as you can... Run 3.0—3.5 springs.... That'll work a treat... Lol

 

[Frankenthe3rd]

Here is some more (popcorn!) bottom out approximations.

Why would you like to have a front end which can carry the braking force? Well, let's take a random apex to apex section (388 meters) from a track. With 11.0 springs you will have the first brake mark, and with 11.5 springs you will have the second brake mark.

So, with 11.0 and 11.5 front ends, you will have about the same speed in apex1, and about the same acceleration from apex, and about the same speed on the straight when you hit the first brake mark. But after that, with 11.5 front end, your speed will still increase a bit, before you hit the second brake mark. And because you are braking later and harder from higher speed, towards the same apex2 speed, your speed will be greater during the whole braking distance.

There are a lot variables, but if we simplify a bit, and assume that front end load carrying capacity is the limiting factor, then for example:

With 11.5 springs, apex1 speed is 126 kmh, acceleration distance 185 m (time 4.136 sec), speed at brake mark; 196 kmh, deceleration distance 203 m (time 5.754 sec), apex2 speed is 58 kmh. Total apex1 to apex2 time is 9.890 seconds.

With 11.0 springs, you have to brake 8.39 meters earlier (acc time 3.981 sec) because front end bottoms out with 0.092G less deceleration, and straight speed drops to 193.37 kmh. Deceleration distance 211.39 m (time 6.054 sec). Total apex1 to apex2 time 10.035, that is 0.145 seconds more than with 11.5 front end.

Right... so you're saying here that having a spring that 'doesn't' bottom out allows you to brake later and harder...

Yet a few pages ago you were saying that bottoming is a good and acceptable thing...

wtf...

 

[Frankenthe3rd]

If you have DDC then you don’t even bottom out before the front starts pushing!

Stupid IMU attempts to keep chassis level by closing valving in forks!!!!! No wonder I’m pushing my front end everywhere!!!

I ordered gp25mm carts and ttx gp, done farting around with DDC I want to race!!!

https://ultimatemotorcycling.com/20...s-stock-bmw-s-1000-rr-claims-wera-sbk-podium/

 

[Frankenthe3rd]

Yeah, I wonder how Nate feels about bottoming out the forks...doubt it..

There is, however, one comment made in that article that does bring into mind "what did they do?"

-----------
With Kerns’ feedback and the information gathered from the datalogger, we decided on a geometry change that would help Kern flick the bike from side to side and corner with better front end feedback.
----------

Front end feedback, corner entry and flickability is what I've felt, and heard from others (Disalvo) is a downside to the S1000RR, so I'm wondering exactly what they did to 'change the geometry'....only thing I can think of on a stock bike would be to raise (or lower) the front forks..and I'm betting lower to make the tail higher than the nose....

Based on the excerpt, it could have been a number of things - raising the rear, raising the front and the rear more (raising the entire bike) or lowering the front by raising the forks through the triple tree. With that said, even a 1mm change can make a big difference. Even just dropping your front preload will create a geometry change because it will sit lower in the stroke.

 

[Frankenthe3rd]

yea I saw that, pretty impressive even in the rain!

"the track dried out for the race"

2017 @ Road Atlanta
QT:
SBK 1:24.555
STK1 1:25.503
SSP 1:27.917
STK6 1:30.067
KTM RC 1:48.295
WERA 1:29.987

Nate Kern: QT 1:32.523/ race best lap 1:31.567
7 sec slower than sbk and 6 sec slower than stk1.

Well, the story is much much better than the lap times...

The point, is that the bike was stock and was competing against bikes that are not stock, and despite its (alleged) limitations for race duties, was still competitive.

Additionally, a lot of people have stated
that the DDC is not suitable for track work, but putting in a 3rd at a decent level of competition with minimal setup time would suggest otherwise.

With that said, they did have the RCK which provides higher levels of adjustability. I get the impression that the difference in feel is what pushes people towards conventional suspension, not necessarily the ability of the suspension to work.

Admittedly, we don't see WSBK teams using the electronic suspension and with the likes of Ohlins kit with years and years of experience and data, I don't see it making inroads any time soon.

 

[Frankenthe3rd]

Admittedly, we don't see WSBK teams using the electronic suspension and with the likes of Ohlins kit with years and years of experience and data, I don't see it making inroads any time soon.

AFAIK, WSBK bikes can only use systems which are in stock bike AND approved by all (major) WSBK manufactures. So, if one stock make/model is missing electronic suspension, it can not be approved/allowed to be used by other make/models. And it must be removed from a WSBK bike, even if it is in stock model.

2017:
f) Electronic suspension:
i) No aftermarket or prototype electronically-controlled suspensions maybe used. Electronically-controlled suspension may only be used if already present on the production model of the homologated motorcycle.
ii) The electronically-controlled valves must remain as homologated. The shims, spacers and fork/shock springs not connected with these valves can be changed.
iii) The ECU for the electronic suspension must remain as homologated and cannot receive any motorcycle track position or sector information; the suspension cannot be adjusted relative to track position.
iv) The electronic interface between the rider and the suspension must remain as on the homologated motorcycle. It is allowed to remove or disable this rider interface.
v) The original suspension system must work safely in the event of an electronic failure.
vi) Electro-magnetic fuid systems which change the viscosity of the suspension fuid(s) during operation are not permitted.

2018:
f. Electronic suspension cannot be used:

Up until this season coming the DDC has been permitted.

 

[Frankenthe3rd]

I guess that he is not applying max braking (and not bottoming out), because of the lean angle.

Pretty sure with that rear wheel off the deck he couldn't be braking much harder.... champ.

 

[Frankenthe3rd]

A bit related to fork oil change.

How many of you who are riding on a track with stock front suspension know what is hydraulic bottom out locks and what it does to front end functionality?
Have you checked if your stock front end has hydraulic bottom out locks or not?

Or are you just staring the (maybe even the very expensive Ohlins one!) zip tie, and smiling, because it always stays "20% off from the bottom out"...
And in reality you might already be in a situation which is almost the same as mechanical bottoming out, and you just dont understand it.

BTW, I have a K-Tech "zip tie" in my front fork. Maybe that is why my front fork is bottomig out? Should a switch to Ohlins zip tie, would that help? Or how about if add Ohlins zip tie to the other front fork? Win-Win!?

You might have seen this one in Ohlins(!) guide:

Well that's all from me...

https://media.giphy.com/media/13aE3Nj8HxO0us/giphy.gif