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Ashley

Do you find the NC750X suspension hard?

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SteveThackery

Oh, one last thing:  I recommend you forget the calculations entirely.  Just stick the suspension unit on the bike, then adjust the preload collar until the static loaded sag is around 50mm.*  Job done.  :)

 

*You'll need some way of getting the back wheel off the ground - a centre stand, or jack under the engine, but not a paddock stand of course! - so you can measure from the axle up to the seat when the suspension unit is topped out.  Then measure again when it's on the ground and you're sitting on the bike.  It helps greatly to have an assistant.

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larryblag
On 03/03/2018 at 19:03, djsb said:

The stiffness of the spring is NOT altered by the spring preload. All the spring preload does is compensate for the STATIC weight of the bike. So, if the free length of the spring is compressed by say 9mm due to the weight of the bike then 9mm of preload can be put onto the spring to maintain the same height. That's how I understand it anyway. Could be wrong though.

Hooks law again I presume, which applies to extension or compression of springs (assuming a linear coil of course - dual rate springs will affect the physics in a way that is far above my 'O' level physics) :cry:

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trisaki
On 09/08/2018 at 22:56, SteveThackery said:

Oh, one last thing:  I recommend you forget the calculations entirely.  Just stick the suspension unit on the bike, then adjust the preload collar until the static loaded sag is around 50mm.*  Job done.  :)

 

*You'll need some way of getting the back wheel off the ground - a centre stand, or jack under the engine, but not a paddock stand of course! - so you can measure from the axle up to the seat when the suspension unit is topped out.  Then measure again when it's on the ground and you're sitting on the bike.  It helps greatly to have an assistant.

Rider sag not static sag 

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Graham NZ

So much has been posted on this forum about suspension and so much seems to have been forgotten.

Unladen sag is how much the suspension settles with the bike on it's wheels with no fuel, rider, any pillion or luggage added.

Laden sag is with fuel, rider, any pillion and luggage added.

Adjusting spring preload alters the ride height not the spring strength.

The forks on the NC bikes are old fashioned technology and virtually impossible to improve enough to match modern standards.

The rear suspension can be made very good with a change to a better quality suspension unit.

It's easy to spend a lot of money when improving suspension, so beware.

For bikes like the NC models it's compliance (comfort over bumpy surfaces) rather than road-holding (wheels not leaving the ground) which is worth pursuing. (Road race bikes have very firm suspension.)

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SteveThackery
On 8/15/2018 at 07:19, trisaki said:

Rider sag not static sag 

 

You are mixing up two different concepts.  There is loaded/laden and unloaded/unladen sag.  I don't think the term "rider sag" is widely used, but I assume it's just another term for loaded sag.  ("Laden/unladen" is grammatically correct, but loads of people use "loaded/unloaded" these days.)

 

And then there is static sag and dynamic sag.  Static sag is when the bike is stationary, dynamic sag is when the bike is being ridden on the anticipated terrain (roads, off-road).  They are sometimes different because asymmetrical damping can "pump" the bike away from its static laden sag height.

 

So there are actually four terms to consider:  static laden, static unladen, dynamic laden and (in theory) dynamic unladen.  The last one isn't real, of course, because you don't see a bike going around a track without a rider.

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Mark8arker

Read this discussion about pre-load twice ( sad i know). Adjust my preload yesterday for carrying a passenger. Was led to be leave the pre-load was for keeking the bike inside its standard opereating ride height. Ie standard ride weight say 13 stone. If you are heaver or increasing wieght of the bike with luggage you increase the pre-load. Placing  the spring back into middle of operating  spec.  After playing around with pre-load setting last couple of weeks. My conculsion are from very nono technical person. More pre load makes the bike feel harder. Less pre load makes feel softer. Very small amouts thou.  It also effects the bike handling.   

Riden my NC750X dct  for 11000 miles now 13months . By far the best commuter bike i have ever had. Buying the bike out right and keeping it.  So going to change the suspenstion with YSS upgrade kit. Will strip and services all the linkage before fitting. After couple of months will do write up. 

 

 

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SteveThackery
20 minutes ago, Mark8arker said:

Read this discussion about pre-load twice ( sad i know). Adjust my preload yesterday for carrying a passenger. Was led to be leave the pre-load was for keeking the bike inside its standard opereating ride height. Ie standard ride weight say 13 stone. If you are heaver or increasing wieght of the bike with luggage you increase the pre-load. Placing  the spring back into middle of operating  spec.  

 

Yes, exactly.

 

20 minutes ago, Mark8arker said:

More pre load makes the bike feel harder. Less pre load makes feel softer. Very small amouts thou.

 

It shouldn't (in fact, can't) make the ride harder of softer (although how something "feels" is entirely subjective and includes psychological elements).  There is one person on this forum who insists it does, but he hasn't given us any evidence or explanation yet.  ;)

 

20 minutes ago, Mark8arker said:

 It also effects the bike handling.

 

Yes, anything that affects the ride height at the back alters the rake angle on the front forks, which affects the handling.

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Tex

Blimey! I thought this thread was dead and buried. Cremation would have been kinder.. :) 

 

Look forward to your findings on the YSS upgrade. But maybe start a new thread? :D 

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SteveThackery

I knew Tex would have to respond.......  :lol:

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Tex
3 minutes ago, SteveThackery said:

 

It shouldn't (in fact, can't) make the ride harder of softer (although how something "feels" is entirely subjective and includes psychological elements).  There is one person on this forum who insists it does, but he hasn't given us any evidence or explanation yet.  ;)

 

As the ‘one person ‘ I thought it was you who were going to provide the evidence to prove me wrong? Something about your Enfield? A challenge you resolutely refuse to accept?! :D:D 

 

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SteveThackery
Posted (edited)
2 minutes ago, Tex said:

 

As the ‘one person ‘ I thought it was you who were going to provide the evidence to prove me wrong? Something about your Enfield? A challenge you resolutely refuse to accept?! :D:D 

 

 

Actually I'd forgotten all about it!  I'm studying for my Master's now, so that gives me a great excuse to say "too busy"!  :)  

Having said that, it would be good to get some actual data one day.  My interest is piqued again.....

 

Edited by SteveThackery
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Tex
1 minute ago, SteveThackery said:

 

Actually I'd forgotten all about it!  I'm studying for my Master's now, so that gives me a great excuse to say "too busy"!  :)  

 

Excellent! That way we can both claim to be right. Or, to put it another way, neither of us can be proved wrong. Perfect!  :niceone: 

 

Although (and strictly in the interests of having the last word ;) ) it’s interesting that you respond to Mark’s statement that increasing preload makes the rider harder by denying what he just said! :D 

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Mark8arker
10 minutes ago, Tex said:

 

As the ‘one person ‘ I thought it was you who were going to provide the evidence to prove me wrong? Something about your Enfield? A challenge you resolutely refuse to accept?! :D:D 

 

My suspension knowledge /experience is from 30 years riding Mountain bikes only lol

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SteveThackery
3 hours ago, Tex said:

Although (and strictly in the interests of having the last word ;) ) it’s interesting that you respond to Mark’s statement that increasing preload makes the rider harder by denying what he just said! :D 

 

I feel guilty now, because you'll have to reply in order to maintain your last word status.  :)

 

My position on the effect of pre-load is based upon what I was taught in my degree, where we looked into suspension operation in some detail.  Two things came out of it: firstly, the lecturer said it didn't make the ride harder; secondly, I don't think there is any mechanism by which it can make the ride harder.*

 

However, in the spirit of good science (to which I adhere vigorously), I absolutely will change my mind if someone can do the scientific thing: propose a rigorous theory of how more pre-load makes the suspension stiffer; and provide some data to back up the theory.  This is just basic science.  Once those are in place then of course I'd change my position - that's how science works.  Meanwhile, I've given extensive explanations of how rear suspension works and shown there is no apparent mechanism by which "more pre-load" can give rise to "stiffer".  So I do feel I've done my bit.  I think it's down to those who assert something for which there is no known explanation to come up with a theory which can be tested.

Nevertheless, some real data might be really useful.  If it does show a stiffening with pre-load, then I'll eat my hat and search out an explanation.  

 

*On bikes with a progressive suspension linkage, raising the ride height by increasing the pre-load actually makes the ride softer.

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Tex

You don’t get away with that! You can’t be so busy you can’t spare five minutes to do the simple test I have been asking (nay, begging!) you to do. Get your Enfield out, wind all the preload off the rear shocks and take a five minute ride. Then, wind them to max preload and ride home. Tell me I’m wrong AFTER you have tried what donkey’s years of experience tells me. Not after doing a bloody degree. I don’t doubt your lecturer was a clever man - but could he even ride a motorcycle? :) 

 

If you really want the last word you will only come back AFTER doing as I ask..  :niceone::D:D 

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SteveThackery
Posted (edited)
10 minutes ago, Tex said:

You don’t get away with that! You can’t be so busy you can’t spare five minutes to do the simple test I have been asking (nay, begging!) you to do. Get your Enfield out, wind all the preload off the rear shocks and take a five minute ride. Then, wind them to max preload and ride home. Tell me I’m wrong AFTER you have tried what donkey’s years of experience tells me. Not after doing a bloody degree. I don’t doubt your lecturer was a clever man - but could he even ride a motorcycle? :) 

 

If you really want the last word you will only come back AFTER doing as I ask..  :niceone::D:D 

 

Immensely clever, and been riding, racing and teaching motorcycle technology for his entire career.  Not always an easy guy to get on with, but incredibly knowledgeable.

I don't mind doing what you ask, apart from one thing: I can't and won't come to any conclusion based on subjective data, because I know it is totally unreliable.  The only way to do this is to instrument up a bike with one or more accelerometers, so we get some proper, scientific data that we can both peruse and discuss.  Like I say, I'm happy to do that in principle, but it will have to wait until my summer break.

 

The only reason I mention the degree is that it requires you to learn some of the theory behind motorcycle dynamics.  This theory is derived entirely from Newtonian physics, so it's totally solid.  I trust Newton far more than my own backside.  :)

Edited by SteveThackery
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Tex

Cool. I await the results of our testing. ‘Our’ testing? Damn right! Just tell me when and where..  :niceone:

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Wedgepilot

What a fascinating thread! 🙂

 

I find myself agreeing with both sides - the theory is solid and I get it, but can so many experienced racers be wrong? 

 

And most importantly, did Ashley ever try adjusting her preload?!? People need to know!

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Dave H

I’ve been riding bikes for over 50 years and I’ve never adjusted the suspension (if adjustments were possible). 

If my bike had poor suspension I would buy a better item in the case of rear shocks or fit better springs and oil in the case of the front. 

This, generally, solved the problem with no further input from me. The rationale being that cheap suspension would not work as well as a quality item. 

Ive listened to friends who raced going on about millimetre adjustments making big differences but I’ve been happy with my methodology so far. 

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Tex
Posted (edited)

 

Quote

And most importantly, did Ashley ever try adjusting her preload?!? People need to know!

 

Alas, we never heard back from Ashley (on this subject) I guess we frightened her off.. :( 

 

She’s still posting though. :) 

Edited by Tex
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Mark8arker

After doing my own  research. I think Tex first answer was correct for the question asked. Having said that. The suspestion on the NC for me is harsh. And no amount change to the preload will improve it lol 

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SteveThackery
7 hours ago, Wedgepilot said:

 

I find myself agreeing with both sides - the theory is solid and I get it, but can so many experienced racers be wrong? 

 

 

Actually, I don't think they are.  Racers care only about sag (which they adjust with the preload) and ride height (which they usually have a separate adjustment for, but the sag adjustment obviously affects it).  If they want a stiffer or softer ride they change the springs and the damping.  I don't think any racer says "Oh, the ride is too harsh, I'll reduce the preload."

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wingrider.steve
On 3/1/2018 at 15:37, Ashley said:

Hiya

 

After the lovely, considered and friendly responses I got to my last daft question, I thought I'd pose another ...

 

I've been spoilt riding pillion on my hubbies GS1200 which seems to float over bumps and potholes, so I'm finding the NC750X's suspension quite hard.  Is this a general opinion, or is it just me being "precious"?  

 

I recently read an article about an NC750 which had had the suspension upgraded (Rally Raid) and it apparently made quite a difference. Is upgrading the suspension a common tweak, or am I just finding it harsh as I'm not that experienced a rider and it feels harder and bumpier than the hubbies BMW?  If this is a common occurrence, what seems to be the favoured option please?

 

Many thanks - you guys are lovely and it's refreshing to find a forum where posts don't quickly become nasty.

 

Ashley

I have the Rally Raid kit (front and rear) on my 2016 NC750X and it has made a big difference to the way the way the bike rides. It has got rid of that harshness and is a lot more compliant over bumps but still very controlled with far better damping than the OEM stuff.

Yes it was expensive and I agonised for some time before purchase whether or not do get it but I do not regret it one bit, it does make a big difference.

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Mike5100
16 hours ago, Mark8arker said:

After doing my own  research. I think Tex first answer was correct for the question asked. Having said that. The suspestion on the NC for me is harsh. And no amount change to the preload will improve it lol 

If you look back in the countless posts on the subject of the harshness, you may find a post by me and I remember at least one other where contrary to all the theories, racking the preload up to maximum on the shock produced a much nicer ride (one-up).  At the time two possibilities were advanced for this effect (if it was real).  One is that on the suspension geometry that Honda use, altering the ride height via preload does more than that (I think they said it alters the effective spring rate - but not by much).  the other possible explanation advanced was that jacking up the rear end altered the weight balance of the bike putting more load on the forks which maybe made them work better.

Mike

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shiggsy
16 hours ago, Mark8arker said:

The suspestion on the NC for me is harsh. And no amount change to the preload will improve it lol 

 

Take a look a the tyre pressures thread, I run my rear tyre at 36 instead of 42 as it helps enormously with the harshness of the roads I drive on.

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