110 miles on MT09SP

[SV650rules]

As an engineer I am having trouble getting my head around static sag ( bike with no rider ) this is a condition the bike is never going to be in when it is moving ( except if rider has fallen off ), but articles I have seen on static sag set it at 5mm or so. I can understand rider sag as this is the position where you really are checking if springs / preload are correct. This article never mentions static sag at all.

https://www.motorcyclenews.com/advic...d-compression/

[Seeker]

A question: if you have a maximum front suspension travel of 140mm and the suspension is correctly set up - how much of that travel would typically be used on an uneven road surface/occasional pothole/ sunken sewer cover (assuming no heavy/panic braking) in, say, 70 miles?

[Bibio]

Originally Posted by Red Herring

stuff.

you are sort of correct in the sense that the spring rate is correct for the rider and bike.

the whole problem arrives when you put a too heavy rider on and then proceed to wind the preload up to get the correct preload.

lets take a rear shock, what the above does is lift the valve on the end of the damper higher within the cartridge which can lead to topping out early say 10mm so you are not using the full amount of (sag) shock travel in rebound situations.

the easy way to tell is when the rider is off the bike and you measure the sag (forget about bike and rider sag) if the sag is less than what you set the rider sag too then you have top out. the difference of rider and no rider is the top out (lets say 10mm) which equals less suspension travel when entering such things as pot holes or braking or acceleration out of a corner due to the suspension topping out early.

if on the other hand you have the same sag when the rider is off the bike then its a bit better and less likely to top out. if you then lift the tail of the bike and it also gives a sag reading then you are even less likely to top out.


as i said earlier, if you have the correct spring rates then you only need to set bike sag as the rider sag will fall into the specified range. this is why we use calculators to work these out.


but people can do what they like and listen to who they like.

Originally Posted by Seeker

A question: if you have a maximum front suspension travel of 140mm and the suspension is correctly set up - how much of that travel would typically be used on an uneven road surface/occasional pothole/ sunken sewer cover (assuming no heavy/panic braking) in, say, 70 miles?

15-20mm from very end of travel. this is fully dependant on rider skill. some riders even with fully set up springs and sag will never use all the travel and the smoother more predictive a rider the less travel they use. smooth progressive and predictive riders can jump on pretty much any bike and not give a shizz. more aggressive riders require the suspension to wok harder so need better set up suspension.

[Seeker]

Originally Posted by Bibio

15-20mm from very end of travel. this is fully dependant on rider skill. some riders even with fully set up springs and sag will never use all the travel and the smoother more predictive a rider the less travel they use. smooth progressive and predictive riders can jump on pretty much any bike and not give a shizz. more aggressive riders require the suspension to wok harder so need better set up suspension.

That's interesting, on my last ride I noticed two things:
1) I started with a full tank of fuel and as the fuel got used the ride quality got steadily more harsh (10 litres of fuel is approx 7.5kg)
2) I wiped the stanchions with a smear of oil before riding and after the ride only about 30mm had been cleaned off which is about 1/3 of the total available travel. There were a couple of occasions when I was bounced off the seat and one "oof" moment as it dropped suddenly knocking the wind out of me.

I normally steer around road patches, sunken drains and all the rest of the obstacles that make up our roads but this time I didn't, instead I let the suspension do its job.

[Bibio]

Originally Posted by Seeker

That's interesting, on my last ride I noticed two things:
1) I started with a full tank of fuel and as the fuel got used the ride quality got steadily more harsh (10 litres of fuel is approx 7.5kg)
2) I wiped the stanchions with a smear of oil before riding and after the ride only about 30mm had been cleaned off which is about 1/3 of the total available travel. There were a couple of occasions when I was bounced off the seat and one "oof" moment as it dropped suddenly knocking the wind out of me.

I normally steer around road patches, sunken drains and all the rest of the obstacles that make up our roads but this time I didn't, instead I let the suspension do its job.

and the above is why race setup settings dont work on road going bikes. could you imagine what would have happened if you hit that pothole mid corner.. with properly set up suspension you dont need to dodge the pot holes.

you need proper spring rates e.g. new springs all round for your weight. along with the rebound and compression set up properly.

[SV650rules]

Originally Posted by Bibio

with properly set up suspension you dont need to dodge the pot holes.

I can't believe you said that, it is always a good idea to keep away from potholes even in a car, but on a bike it is even more important... ( unless it is an off-road bike ).

[Seeker]

Originally Posted by Bibio

you need proper spring rates e.g. new springs all round for your weight. along with the rebound and compression set up properly.

therein lies another problem. The local tuning/suspension place is telling me he is having difficulty in finding springs for my weight for the forks. I find this hard to believe so I've emailed a dedicated suspension agent to see if he knows if they are available.
I think the problem is not that the springs are not available - it's that nobody (yet contacted) is sure what size springs are in the fork.

I have also emailed the KYB UK office to see if they offer softer springs - I don't know which KYB fork model is fitted to the bike, it may be unique to Yamaha although that sounds unlikely.

The 600 mile service is scheduled for mid August and I'm ramping up the miles as quickly as possible so I can go back to riding the SV. Riding the Yam is not a pleasant experience. I've now done 320 miles and on the last 2 tankfuls 60mpg which surprised me since I'm giving it varying loads.

[shiftin_gear98]

Seeker,

I think you need to bolster this company's sales, I'm sure they must be struggling like all companies at the moment. The more you spend, the less of a problem you'll have with your suspension.
You're MPG might suffer though.

https://www.pukkapies.co.uk/

[Adam Ef]

A quick way to find out is fit a load of weighted down luggage to the bike. Ideally a tank bag and tail pack with 8kg or so in each and see if adding weight helps.

[Seeker]

Originally Posted by shiftin_gear98

The more you spend, the less of a problem you'll have with your suspension.

https://www.pukkapies.co.uk/

but then my gear won't fit... and Boris wants us all to be trim...

I phoned Yamaha which didn't really help, they told me the bike had progressive springs in the forks (6.86Nm to 9Nm) but also told me there was an Ohlins kit for heavier riders (I know that's the opposite of what I want but I thought some specs might be teased out). As it turns out the kit they suggested was for the Tracer anyway. Yamaha couldn't tell me spring length and I'm unsure whether I believe their spring rates, they didn't radiate confidence.
KYB UK pointed me to a Belgian company that handle KYB bike forks, only they specialise in off road and don't service 41mm forks.

Originally Posted by Adam Ef

A quick way to find out is fit a load of weighted down luggage to the bike. Ideally a tank bag and tail pack with 8kg or so in each and see if adding weight helps.

I did consider this, I'd have to use a backpack and I was a bit concerned about stability. Fill my boots with water?