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What the hell? Is the front spring tapped out 7th gen?


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  • Forum CEO

So I got an ohlins from a 5th gen that I put on her a couple of years ago - but the front end is stock. Finally got around to measuring sag, I put a zip tie on the fork tube and went about measuring the distance between the zip tie and the top of the fork leg where the oil seal is. 50 mm? OK so I crank on some more preload, put the zip tie snug, sit on the bike carefully then put my phillips head stand on and lift the suspension off the ground and still 50mm? WTF? Brain fart maybe so I crank the preload all the freaking way full hard and then do it all over again 50mm? JEBUS what the hell? So I crank it all off and and got about 5 lines showing? 50mm? so this thing is really that under sprung? Is the stock spring tapped out for a 220 lb guy like me? What am I doing wrong? I just set it where I had it to start with and start wondering if the veefalo is too softly sprung on the forks that preload adjustments make no difference? I tested the zip tie it was snug it wasnt just falling off?

The ohlins I was able to adjust from 50mm to 35mm sag but the front is just 50mm no matter what? I think I need stiffer springs? I got the rebound set at 6clicks from full hard (stock) and like it there. Just trying to get it to behave a bit quicker in the tight stuff. I got the rear shock just about full preload too, I am thinking I need stiffer springs all around?

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  • Member Contributer

Sure looks that way doesn't it? Measurements don't lie. Stock bikes are notoriously undersprung for guys like us. Upped the spring rates on my 5th gen considerably once already, and while it's much better my finding is I need to go a bit more to have them optimal.

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Measuring sag by yourself is notoriously inaccurate as any added movement shifts the position of the tie. The best method is having 2 assistants, one to hold your bike vertical as you sit, the other makes the measurements. But beyond measurement method, in principle the pre-load position has nothing to do with hardness or softness of the spring. Preload is nothing more than a ride height adjustment. This is counter to most peoples intuition because so much disinformation is spread about preload.

Put on your engineering hat for a moment. For a given constant mass, the preload is merely a displacement offset which raises or lowers the mass sitting on TOP of the spring. The bottom position of the spring is fixed relative to the ground and the mass compressing the spring (you plus bike) is constant in this case, therefore the spring length is constant under compression (this assumes small angle changes to the height of the front end of the bike i.e. cosine[angle] ). From this, one can deduce that the top position of the spring is constant with respect to the ground. Therefore the preload spacer which sits at the top of the spring is doing nothing more than displacing the height of the mass above the spring, in other words the ride height.

This principle has nothing to do with the spring rate whether soft or stiff. Preload does not alter the spring rate in any way by the argument just stated. That said, the VFR does seem to have relatively soft springs. When my front end was reworked by Lindemann, he replaced the stock progressive with linear at 1.0kg/mm rate which is moderately stiffer than stock. 1.1kg/mm may even be better for the weight of the VFR. He also added more internal pre-load offset (i.e. fixed spacer) to set my front sag at 40mm with the pre-load adjuster in the middle position.

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  • Forum CEO

I will skip the engineering lecture since I am on record here saying all that before myself, hard our soft was used to explain the direction I took in regards to the preload adjustments I made, just simply the quickest way to get the point across. Not a belief in making a spring harder or, I think that speak is pretty common really.

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I am on record here saying all that before myself,

I know, and also that you know that adjusting the preload adjuster should translate 1:1 to sag. Weird, it is as if the spring seat washers are missing makeing the adjusters inoperable.

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Since I dont know your entire history of statements on this board, I could not have assumed otherwise. Your description of the problem offered no clarity of understanding the issue at face value, hence the "lecture".

Sent from my DROID BIONIC using Tapatalk 2

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Since I dont know your entire history of statements on this board, I could not have assumed otherwise. Your description of the problem offered no clarity of understanding the issue at face value, hence the "lecture".

Sent from my DROID BIONIC using Tapatalk 2

:lurk:

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Here's my observations, and it does seem odd.

Running on the assumption that sag should be aprox. 1/3 of total fork travel (33%), and the 1200 front fork total travel is 4.7 inches. This means I want 1.5 inches of sag from full extension.

I set my tie around the fork tube and slide it up to the fork seal. Straddle the bike and then lower myself onto the seat, with a bit of force to compensate for fork stiction, and be sure my feet aren't taking any weight. I then get off the bike and put it on the center stand. This operation does not compress the forks more than when I sat on it so my tie remains accurate. I jack the front tire off the ground (jack under sump) to top out the fork.

I measure from the seal to the top edge of the tie and get 2 1/8 inches. Obviously more sag than I want, this is close to half of the fork travel (stock preload setting, 2 lines, I'm 190 lbs).

I turn the adjusters down 4 turns and re-measure. Now I get 2 inches of sag, reducing it by only 1/8 inch. Which makes sense as the adjuster only screwed in about 1/8 inch in those 4 turns. I need another half inch of preload and the adjuster isn't going to give me that.

I thought the adjuster would have a multiplying mechanism inside but it doesn't appear so. This would explain why your adjuster didn't seem to make any difference, because it simply doesn't have the travel to do so. Proper sag on this fork is going to require internal spacers as far as I can tell.

Or be happy with 45% sag

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I'm not an engineer & I don't bother with formulas or complexity when something doesn't happen, that you expect to happen, the bottom line is just fix it :-)

Suspension as said many times is a black art & I'm sure Hispanicslammer knows his way around suspension better than most going from some of his write ups. At a guess the sag isn't changing much because the minimal amount of preload your inputting to existing springs isn't enough to make a change & the hydraulic lock is simply negating that small amount of preload adjustment. Any bike when you set sag you can achieve different measurements when bike is cold hasn't been ridden so fork components/oil cold to being hot & even the amount you bounce front end before taking measurements, it's not an exact measurement it's ball park & an individual should always fine tune preload on how the bike rides.

Fact is all bikes released don't have spring rates etc to suit everyone & the VFR1200 in my view from factory has been set up a certain way to cater for the shaft drive & is even more plush that any VFR released before it. As mentioned by AB above we have a good friend who has the VFR1200 & he hates it even with Penske rear shock & adapted CBR1000RR Ohlins cartridge kit forks. Now part of why he hates it is expecting to ride it like a sportsbike or past VFR'S which it will never be like & he simply made a mistake buying for that requirement. But he is a big lad & just to try to find a happy balance between fork/shock has been a major effort with rear shock spring changed out 3 times going heavier & heavier much more than any data suggests & the forks also having constant internal changes. All this plus the fact the suspension components he has have major external adjustments & it's still not close to what he would like even taking away he thinks it should handle like a sportsbike. I have added above not as a lecture but as an example of a problem one individual has had setting up the 1200 to his liking.

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Miguel-

I've ordered new springs from the local shop due to the same issue...

Being a fat guy, EVERY bike I've owned has been undersprung, and I've got the same issue with sag/preload.

Depending on the difference in feel I might go for a valve changeup too... we'll see.

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Miguel-

I've ordered new springs from the local shop due to the same issue...

Being a fat guy, EVERY bike I've owned has been undersprung, and I've got the same issue with sag/preload.

Depending on the difference in feel I might go for a valve changeup too... we'll see.

Please report back on your results. I'm also "on the large side" and I'm very interested on how this works out for you.

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Miguel-

I've ordered new springs from the local shop due to the same issue...

Being a fat guy, EVERY bike I've owned has been undersprung, and I've got the same issue with sag/preload.

Depending on the difference in feel I might go for a valve changeup too... we'll see.

Please report back on your results. I'm also "on the large side" and I'm very interested on how this works out for you.

I will... Finding time to get the work done is the trick... Bike's my only transport and I'm working 6 day weeks.

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  • Forum CEO

Solo, no offense taken just trying to get to the root of my problem - why there is no adjustment in the forks! I pretty much followed what tamworth was doing, since I dont have an assistant to help with the measurements the zip tie trick is the best option. Taking it very easy not to slam the forks getting on and off the bike sitting on it and raising my feet off the ground for full weight had no effect on the final measurement, leading me to believe I have the forks compressed as far as it will go - or you could be correct in that the zip tie method introduces too much shock into the placement of the zip tie and I am getting a false reading? I just set it back to where I had it to begin with - at least I know what I am getting there but I am thinking I need stiffer springs

so Tamworth you are saying its 4.7 inches travel on the forks what about the swingarm? its not like older vfrs the travel is different front and back, the older bikes had the same travel on the front and back - not the vfr1200! I usually go for 1/4 -1/3 total travel since getting it perfect is difficult this gives me a range to get the measurements in, 1/4 if I am riding more aggressive like a track day.

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  • Forum CEO

I am hovering around 215 lbs now after losing 35lbs since last year, so I was perplexed as to why I am getting 55mm of sag when thats what I got last year when I measured it before I took my calif trip. Then cranking the preload so no lines were showing, starting from three showing, I thought I should at least get to around 50mm, since well thats the aprox distance I cranked the forks up to? three lines 5mm?

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  • Forum CEO

I might just take the forks apart, figure out the spring rate and cut them, and grind the ends flat, to make a stiffer spring then cut appropriate length spacers to get the sag into the correct range. I have a spring rate calculator I just need to figure out how many coils to cut off to get the best spring rate.

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Just a though, not knowing the design of the internals but if top out spring used it could be masking the preload adjustment as far as measuring sag in static environment.

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Yep the stock springs are useless for guys > 100K. I myself bought a set of the racetech 1.2K springs along with the G2-R gold valves. My bandit also has the Ohlins rear SU-714 and it was under sprung at 170 N/M so I got the 180N/M spring and had that same issue you did. Now my preload is all the way out and my bike is a bit taller but it fits me fine and does not dive as much under hard braking. I was also told that once you springs "bed in" you will loose some preload ability, talking about your last trip and now.

Mark

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+1 You must have some internal shock problem, at the least there should been some change with the adjustments you made .

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snip

so Tamworth you are saying its 4.7 inches travel on the forks what about the swingarm? its not like older vfrs the travel is different front and back, the older bikes had the same travel on the front and back - not the vfr1200! I usually go for 1/4 -1/3 total travel since getting it perfect is difficult this gives me a range to get the measurements in, 1/4 if I am riding more aggressive like a track day.

Rear suspension has 5.1 inches travel (at the wheel center). These front and rear travel specs I found on-line, couldn't find it in the workshop manual.

I have successfully set the rear sag to 1/3rd of total travel (1.7 inch), it has required me to set the knob from the recommended 11 clicks from soft to 4 clicks from soft. In other words barely any preload. At least when I sit down both ends of the bike settle evenly, but my front is still around 45% sag with the adjusters cranked in full (but for a half turn). Not sure I personally need stiffer springs but certainly a spacer is in order to get around 33% sag.

As you likely know, it's almost essential to dismount the rear shock preload adjuster to get enough grip to actually turn it.

I'm happy to just get the sag close as it is so far off at stock settings, even with my 190 lbs which should be pretty average.

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why there is no adjustment in the forks!

Well that's easy, your forks are on upside down! :tongue:

Actually I seem to remember something different about setting/adjusting Inverted forks, can't remember what it is but.... :huh:

BR

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