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IanC

Cannot set sag on rear?

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thetyrant
32 minutes ago, Julian said:

For sag you need 3 measurements, A B and C. The measurements should always be taken between the same two points, one being the rear axle and the other one a fixed point on the tail of the bike directly above the rear axle. You can put a piece of tape on the tail to make sure you are measuring to the same point, and the same person should take the 3 measurements for consistency.

For measurement A you need to grab the bike under the tail or from the pillion pegs and lift it until the rear tyre is in the air and there is no weight on it at all. You need two people to lift the bike and a third one to measure, unless you are very strong. 

Measurement B is done between the same points with the rear wheel on the ground and the bike unsupported.

Measurement C is done between the same points with the rider on the bike in the normal riding position and the feet on the pegs.

A-B is your static or free sag, and it will not be 0 because the bike does not weigh 0 and the suspension is elastic. 

A-C is your rider sag. 

You are aiming for 5-10 mm free sag and 30-40 mm rider sag but on a street bike with stock suspension you will never get the ideal numbers that you see in the videos. I have 6-7mm free sag and 34 rider sag which is very acceptable.

For some reason your not getting what im saying :(  to put it into your terms my measurement A and B are the same give or take maybe 1mm max (too little to measure really).

So the spring rate with minimal preload setting  is great enough to lift the bike to top of its suspension travel when there is no rider onboard, only just but it is...

I agree your numbers are good and what i would like to see, however with preload on minimum i cant get the 5-10mm static sag i would like, same as the original post starter found.

 

Hopefully this makes sense :)

 

Edited by thetyrant

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Julian
3 minutes ago, thetyrant said:

For some reason your not getting what im saying :(  to put it into your terms my measurement A and B are the same give or take maybe 1mm max (too little to measure really).

So the spring rate with minimal preload setting  is great enough to lift the bike to top of its suspension travel when there is no rider onboard, only just but it is...

I agree your numbers are good and what i would like to see, however with preload on minimum i cant get the 5-10mm static sag i would like.

 

For the sake of clarity, measurement A is taken while the tail of the bike (NOT the swingarm) is lifted and the wheel is hanging underneath it without touching the ground. After you put the bike down, I refuse to believe that the measurement is the same, that would only happen if the wheel was welded to the frame basically. Maybe you don't realize how little 4-5mm is, it is tiny but not zero.

Also are you sure that you are minimum preload (1), and not maximum (7)? You can take pictures or a video and post it because you must be doing something wrong. We have the same suspension so your free sag should be about the same as mine.

 

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Triple Jim
42 minutes ago, Julian said:

After you put the bike down, I refuse to believe that the measurement is the same, that would only happen if the wheel was welded to the frame basically.

What you're saying is true only if there is little or no preload.  It could happen if the preload of the spring is more than the load from the weight of the motorcycle. 

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thetyrant
39 minutes ago, Julian said:

For the sake of clarity, measurement A is taken while the tail of the bike (NOT the swingarm) is lifted and the wheel is hanging underneath it without touching the ground. After you put the bike down, I refuse to believe that the measurement is the same, that would only happen if the wheel was welded to the frame basically. Maybe you don't realize how little 4-5mm is, it is tiny but not zero.

Also are you sure that you are minimum preload (1), and not maximum (7)? You can take pictures or a video and post it because you must be doing something wrong. We have the same suspension so your free sag should be about the same as mine.

 

Ok well its upto you what you believe but ive seen it with my own eyes, as has the guy who started this thread :) 

Just to confirm again when the bike is sat upright with me holding tail section and i bounce the suspension then allow to settle i can not lift the tail section up to top the suspension out... as its already there!, there is a tiny tiny amount of movement maybe 1mm maximim if im generous and will try and take an exact measurement later if i can,  i work in fractions of mm in my day job so i know a small amount when i see one :))  

Im 100% sure im on minimal preload yes and ive checked that again today to be 200% sure.

 

 

 

 

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Julian
18 minutes ago, thetyrant said:

 

Just to confirm again when the bike is sat upright with me holding tail section and i bounce the suspension then allow to settle i can not lift the tail section up to top the suspension out... 

 

 

 

 

At this point I feel like I'm talking to a wall 😂. From your own words you are not doing what I described. You bouncing the suspension has nothing to do with it. That is not how you measure it! I described very clearly how it needs to be done and you need 3 people and you need to take actual measurements with a tape measure. Until you do that there is nothing more to talk about...

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Julian
31 minutes ago, Triple Jim said:

What you're saying is true only if there is little or no preload.  It could happen if the preload of the spring is more than the load from the weight of the motorcycle. 

 

1 hour ago, M. Hausknecht said:

Julian, all correct except for your assertion there cannot be zero static sag. To have zero static sag all you need is sufficient preload on the spring, such that the preload on the spring (for example, one inch of preload on a 7oo inch/lb spring, so 700 pounds) is a higher weight than the force placed on the spring by the unladen weight of the motorcycle (of course, because of linkages and the angles of the linkages and the spring assembly itself, the relationship between spring preload and load on a tire is not one-to-one). You are correct that a spring without installed preload will always collapse a bit when a load is placed on it; installed preload can reduce or eliminate that collapse (that is why we add preload to get the laden sag where we want it).  Finally, to get the correct static sag and the correct laden sag, you need the right spring(s) and preload.

You are both correct, but only in theory. Here we are talking about a concrete bike that we are familiar with and about the stock shock. In that context zero is impossible. 

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Triple Jim
2 minutes ago, Julian said:

You are both correct, but only in theory. Here we are talking about a concrete bike that we are familiar with and about the stock shock. In that context zero is impossible. 

Ha, well my MT-07's rear suspension is set at  the preload setting that it came with from the dealer.  Without my weight on it, the rear suspension is topped out firmly.

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Julian
2 minutes ago, Triple Jim said:

Ha, well my MT-07's rear suspension is set at  the preload setting that it came with from the dealer.  Without my weight on it, the rear suspension is topped out firmly.

You have a 2018 right? From my measurements there are 4mm free sag at the preload setting. It's not a lot but it's something.

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Triple Jim

It's a 2020, so probably the same as a 2018.  There is absolutely zero sag without a rider on it.  In fact if I sit on it and then raise myself off the seat slowly, I can feel the "clunk" when it tops out.

Edited by Triple Jim
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2019_MT07_Owner

I'm with thetyrant and Triple Jim on this issue.

I have a 2019 MT07 and it has zero static sag - if there is any static sag its too small to measure with a tape measure that has 1mm increments.

We just have to accept that there is zero static sag and its not too much of a problem.

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Triple Jim
26 minutes ago, 2019_MT07_Owner said:

We just have to accept that there is zero static sag and its not too much of a problem.

Well, sag without a rider is nearly meaningless so I pay no attention to it.  Sag with the rider is what I'm concerned with.

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thetyrant
13 hours ago, Julian said:

At this point I feel like I'm talking to a wall 😂. From your own words you are not doing what I described. You bouncing the suspension has nothing to do with it. That is not how you measure it! I described very clearly how it needs to be done and you need 3 people and you need to take actual measurements with a tape measure. Until you do that there is nothing more to talk about...

I feel the same regards the wall lol   ive done exactly what you said as well as using the bounce/settle method and if you dont understand why i do that we will just have to agree to disagree,  as you can see above im not the only one and just because your bike is different doesnt mean others are the same ;) ive been riding for 35+ years and learnt you can only go with what you have in front of you :D

 

 

Edited by thetyrant

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thetyrant
37 minutes ago, 2019_MT07_Owner said:

I'm with thetyrant and Triple Jim on this issue.

I have a 2019 MT07 and it has zero static sag - if there is any static sag its too small to measure with a tape measure that has 1mm increments.

We just have to accept that there is zero static sag and its not too much of a problem.

Yes same as mine, i agree the zero static is not end of world and i guess it depends how heavy you are and type of roads you ride as to if its a problem, im fairly light and ride bad roads on occasion without choice so i do get the top out/seat kick on bad sections, its not terrible ive had much much  worse but would like to improve it if i can, Nitron or similar will probably be coming for next season :D

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