Lowering rear suspension

[Old Steve]

OK, I'm seriously considering lowering the bike.  Front forks seems straight foward, loosen, raise the forks in the head and re-tighten.  Probably go down 40 mm

On the rear coil, there are a couple of different ways and this raises the questions:

Should I clamp one turn of the spring to shorten the spring?

Should I cut the existing spring - is the spring clamped in at the top and bottom?

Should I have a new spring made?

What difference in reduction will make no noticeable change in handling - eg. can I lower the front forks more than the rear, say lower the front forks 40 mm yet only lower the rear 25 mm, or 30 mm?

Has anyone done this already?

Photos would be taken during the process and an update posted here, whichever path I take.

[Chatty]

I wouldn't be lowering the front forks through the triple clamps - by doing that you change the front geometry quite substantially which will in turn seriously affect the handling of the bike.

This bloke gives a pretty good explanation:  http://sportbike.natkd.com/motorcycle_geometry_101.htm

Rear spring - I wouldn't be clamping the spring as that will affect the spring rate and then the bike's response to bumps and once again handling.  There is also the risk of the clamp coming off unexpectedly (Murphy's Law says mid-corner) and seriously upsetting the bike.
Cutting springs yourself is not something I would do - they are made from a special steel that doesn't cut easily and if you overheat the spring in cutting it you will affect its properties.  There is also the problem of getting a flat seat again.

My advice would be, unless you are an absolute expert on motorcycle suspension then don't try this at home - take the bike to an expert who can do the changes and still leave the bike safe to ride.  Keep in mind that if you make these sorts of changes yourself and don't have them approved by an engineer (or suspension expert) then your insurance company will more than likely disown you when you have an accident.

Either that, or if the ST is simply too tall, get a bike that is the right height for you.  I have in the past had to walk away from buying a bike that I really liked simply because it wasn't the right height for me.

Chatty

[Old Steve]

Thanks for the advice Chatty.  I love my ST, but the seat is just a little high so that only the balls of my feet reach the ground.  It's OK while I'm riding solo, but now my wife has agreed to ride pillion I wanted to be able to put my feet flat on the ground so the bike is more stable while she clambers on the back.

I'm getting a back rest made to attach to the front of the top box, so I've gone back to the upholsterer and got a quote for taking the seat down a little.  So I'll try that.  The upholsterer rides a Ducati, and seems to know what he's doing.

[Chatty]

Thanks for the advice Chatty.  I love my ST, but the seat is just a little high so that only the balls of my feet reach the ground.  It's OK while I'm riding solo, but now my wife has agreed to ride pillion I wanted to be able to put my feet flat on the ground so the bike is more stable while she clambers on the back.

I'm getting a back rest made to attach to the front of the top box, so I've gone back to the upholsterer and got a quote for taking the seat down a little.  So I'll try that.  The upholsterer rides a Ducati, and seems to know what he's doing.

Got the first problem fixed here - Trish has her own bike, so no worries about pillions clambering on or off.      I've seen some who leave the bike on the side stand while their pillion gets on or off - not sure I would want to be putting that much load on it though.

I think you might be on the money with having a slice taken out of the seat - others on here have done the same thing.  Did your top box not come with a back rest?  I thought the back rest was standard on the ST top box... 

[Old Steve]

Mines a cheap aftermarket top box, functional but not aesthetically in keeping with the rest of the bike.  If what I plan on doing works then I might be looking for a genuine white ST1100 top box.

[Chatty]

Mines a cheap aftermarket top box, functional but not aesthetically in keeping with the rest of the bike.  If what I plan on doing works then I might be looking for a genuine white ST1100 top box.

No probs - I got mine through David Silver Spares - at the time the price including freight to Oz was about half the price of a genuine Honda one sourced from a dealer, and still cheaper than an aftermarket Givi or similar sourced locally.  And David Silver Spares are just so good to deal with.

[Greencan]

Evenin' Steve et al...

Something you might want to keep in mind is the total swing arm travel is 120mm, now subtract 20mm to 30mm for un-loaded sag once any shock/spring combination is attached to frame and final drive, then when your sitting on it you take off another 10mm to 30mm, which will leave you about 70mm to 90mm of remaining travel for the shock/spring combination to work with. This is before you begin messing with spring lengths. Not really a practical solution is it.

The only practical (& l am using that word very loosely), way l have seen a modern bike lowered on the back end (Triumph GT Sprint), had plates made to fix to the swing arm attach / pivot points, thus lowering the frame about 25-30mm. Steve I cant see how this is mod could be used on a shaft drive ST.

Also the Trump owner could no longer use the centre stand as the lowering had shifted its fulcrum point rendering it inop. Ground clearence both vertical and turning became a big issue too.

As for extending the front stanchions up through the top an bottom triple clamps, well others have correctly addressed the pitfalls with that.

Just a thought.

Ciao the can:-)