5mm rear ride height spacer

[8541Hawk]

Well I haven't posted anything in a while, so why not stir the pot a bit...lol

Adding a 5mm ride height spacer has been a common mod on a VTR for many years. IMHO this has now become too much of an increase and the bike can handle better with less of a change.

I know this, once again, goes against the "common knowledge" of the board but I have my reasons for this belief.

This all started while doing maintenance on my rear shock. I had it out to clean everything and noticed the ride height adjuster was 1\4 turn too far out.
So I had 5.25mm of added height instead of 5mm. Shouldn't make a difference for street riding was the thought and went for a test spin when all was back together.

What was amazing was the bike was totally different. Much more stable and planted but the side to side transition felt the same.
So same quick handling but more planted. I really couldn't believe a .25mm change would make that much difference.

Since I have a ride height adjustment on my Ohlins (on a side note Ohlins has 2 different adjusters available. One is -3 to +3 and the other is +3 to +10. So if you happen to acquire an Ohlins with ride height adjustment, check to see which one is installed ) I started to drop it down more.
It just kept getting better. I am now running at +3 and am more than happy. Would try even less but that is as low as I can go.

After that it was time to sit down and figure out why? The old set up had always worked fine and I had even run more that +5mm in the rear with no issues.
Took a minute but the light finally turned on and, again in my opinion, the answer is that rear tires have changed.
Over the last 20 yrs the rears have become much taller. This changes the rear suspension geometry and IMHO make the +5mm spacer too big.

Again this is just my recent experience and the last VTR I set up I ran a 2mm spacer and was more than happen with the way the bike turned in.
YMMV but it is just something to think about and swapping the spacer is an easy thing to try out if bored one weekend

[MacV2]

Interesting...

Good point re the tyres...

[sirch345]

An interesting post Mike.

Slightly off topic I know, as you reduced the ride height did you need to adjust the rear static-sag as well each time to keep it at your preferred setting

Chris.

[fabiostar]

good points indeed. it comes down to personal feel i suppose? i actually like mine with the 6mm spacer and the blade forks because it tips it on its nose. that probably comes from my background in supermoto racing with bikes that steered like lightning lol .

plus at ten stone soaking wet i find the sharper steering makes it flop into corners for me instead of having to wrestle it as much.

its near at the point of being unstable on faster corners but,its upto but not across the unstable line. horses for courses i suppose

[popkat]

On the standard shock I think 3mm spacer is enough, but on an aftermarket shock you can go more, reason being you can set proper sag where the std shock doesn't have much at all (and the spring is too hard) this means that for the same length shock you may well be sitting the bike lower at the back with an aftermarket shock.
The storm is a bit rear biased as standard so to lower even more doesn't make sense to your feeling but if it works for you that's ok, watch for bars slapping over bumps if you have no damper as the front goes light.
There's more, when you do fork mods it alters the weight distribution, the std forks sag a lot, when putting the correct rate springs in and bringing sag to a good 25-27mm your raising the front by 10mm of more, it's common to then raise the forks in the clamps which is needed but if you raise 5mm your still higher at the front making the bike more rear biased. but to lower the front but 10-12mm no one does. in theory you could lower that front and raise the rear by probably 10-15mm and have a sweet handling bike, I have not tried this. the most I did was 10mm front drop, rear Ohlins with 3mm spacer and 8mm sag, this was for track running race tyres and it worked well enough to win (needed the steering damper though). on the road mine have always been more conservative, but these days I find the storm a very lazy handling bike which makes it feel heavier than it is (very planted in long fast corners where it excels). I may well have a play with mine and go a bit more radical, it currently has forks at 5mm, rear shock (WP) slightly longer than stock and a 3mm spacer, about 12mm sag. bike is stable unless you hit bad bumps, when it can go into a slapper (that'll be the rear bias)
If altering the weight bias doesn't work then it must be in the geometry of the chassis itself ?
Just as a comparison (maybe not the best one) My VFR race bike steers and turns faster than my storm, it's weight is 51% front 49% rear, and it started as a sports tourer similar to the storm, it has a damper but it's always on minimum setting so maybe not needed.


Re tyres a 180/55 is a 180/55, they are no taller now than they were then, the industry has regulations about size variations within a stated size.

Ohlins over here do not have ride height. suspension shops can alter them though, maybe US importer does this.





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[eamonn]

.25 of a mm WOW , who would of thought that ?

[sirch345]

There's more, when you do fork mods it alters the weight distribution, the std forks sag a lot, when putting the correct rate springs in and bringing sag to a good 25-27mm your raising the front by 10mm of more, it's common to then raise the forks in the clamps which is needed but if you raise 5mm your still higher at the front making the bike more rear biased. but to lower the front but 10-12mm no one does. in theory you could lower that front and raise the rear by probably 10-15mm and have a sweet handling bike, I have not tried this. the most I did was 10mm front drop, rear Ohlins with 3mm spacer and 8mm sag, this was for track running race tyres and it worked well enough to win (needed the steering damper though). on the road mine have always been more conservative, but these days I find the storm a very lazy handling bike which makes it feel heavier than it is (very planted in long fast corners where it excels). I may well have a play with mine and go a bit more radical, it currently has forks at 5mm, rear shock (WP) slightly longer than stock and a 3mm spacer, about 12mm sag. bike is stable unless you hit bad bumps, when it can go into a slapper (that'll be the rear bias.

From memory there was one guy on here who used to run his Firestorm forks 30mm of more above the top yoke
I'm not sure I'd be brave enough to try that myself, but it worked for him. I think his forks had been reworked by Roger D. and he had an after market shock if I rememeber correctly, he may have had a steering damper too

Chris.

[Chris58]

Mine is all stock with a 10mm spacer over the rear shock. I didnt notice much difference at all... maybe it corners a little quicker, but it is still very stable.

[E.Marquez]

Re tyres a 180/55 is a 180/55, they are no taller now than they were then, the industry has regulations about size variations within a stated size.

No, not really.
Its a guide line more then a "standard" because it is not regulated at all and even if two tires are the exact same size 180/55 the tire shape or profile is likely different one tire brand/ model to another all meaning 180/55 is not always 180/55

Stolen to say what Im trying to illustrate

How can tires of the same nominal size designation vary in diameter and width?

One reason is that the Tire & Rim Association's voluntary guidelines, which most manufacturers follow, afford designers considerable latitude in determining tire section width and outer diameter—provided the sum of these two dimensions meets or exceeds the ``minimum size factor'' established by the TRA.

[popkat]

Re tyres a 180/55 is a 180/55, they are no taller now than they were then, the industry has regulations about size variations within a stated size.

No, not really.
Its a guide line more then a "standard" because it is not regulated at all and even if two tires are the exact same size 180/55 the tire shape or profile is likely different one tire brand/ model to another all meaning 180/55 is not always 180/55

Stolen to say what Im trying to illustrate

How can tires of the same nominal size designation vary in diameter and width?

One reason is that the Tire & Rim Association's voluntary guidelines, which most manufacturers follow, afford designers considerable latitude in determining tire section width and outer diameter—provided the sum of these two dimensions meets or exceeds the ``minimum size factor'' established by the TRA.

My point was a 180/55 tyre was the same back in the early 90's as it is now. not getting into different manufacturers variations in sizes, just the size is the size. The original post implies that an older 180 is a different size (not as tall) to one you can purchase now which as far as I'm concerned is not the case.



.

[E.Marquez]

My point was a 180/55 tyre was the same back in the early 90's as it is now. not getting into different manufacturers variations in sizes, just the size is the size. The original post implies that an older 180 is a different size (not as tall) to one you can purchase now which as far as I'm concerned is not the case.

Ahhhh, got ya, I missed that part.

Agree I can find no information at all that points to older tires being of a physically different size.
Since at least 1964 European Tyre and Rim Technical Organization (ETRTO) and the Tire and Rim Association (TRA) are the two organizations that influence national tire standards, and the standards we have today are the same as they were in the 70's and on. As I said earlier as the standards are not regulated and enforced its possible some manufacture in the past decided to make a tire that when mounted was taller that the standard laid out for the size marked on the tire. But that same possibility exists today as well.

[Beef]

I was told that the reason why two tyre manufacturers of the same tyre size may differ in width and height is because the carcass is set by the size and not the wearing surface!! Dunno how true it is, but I have always stuck to manufacturers tyre sizes on my bikes and been surprised how some tyres look so much wider than others!