Mono shockers

Tony Norton · Nova Slayer Joined: 30 Aug 2007 Karma :

Hi all,

didn't realise it's been so long since I was last on the forum.

However, I've just traded in my Eliminator in for a KTM Duke, the 390 A2 version. This is necessitated by the fact that, in my experience, pretty well every bike have had, has a fault. Which is - as they age they get heavier!

So I opted for the lighter KTM. I am in the process of sorting out how to lower the seat height to suit my shortness in the legs. I propose to do this by changing the rear mono shocker for a slightly shorter one. Please don't all leap up and down screaming about ruining the handling and or the balance. At my age (88) my predominate usage is the 3 mile round trip to the local shop to get my daily paper. A 'fun' ride is from Bournemouth to Lyndhurst, round the one-way system, and back home again. You won't catch me doing track days, or measuring my trips in 100s of miles.

My problem is that in doing the sums on this job I need to know all the dimensions of whatever shocker I choose. Most manufacturers give the overall length, spring overall size and diameter of the 'wire' used. What most of them don't give is a figure for the stroke. In my mind this figure is essential, as I don't want to land up with a unit that 'bottoms out'.

WP-suspension do a kit: -

"https://www.ktm.com/en-gb/parts---wear/powerparts/products.html?c1=1001509634&year=2025&segment=Naked%20Bike&model=F4302Y4L&product=1003856209"

but it is a bit more than was willing to spend and also involves one in dismantling the front forks, which is not something I wish to get involved in. This kit only renders a reduction of 25mm. Whilst this is probably enough, once I've removed the pillion seat (something I've done on practically every bike I've had) but I think I would prefer a bit more than that.

One supplier I contacted quoted "around 30mm" for the stroke. Even Apex, who do the standard fitment, only give an approximate figure of 55mm.

There must be going on for 50 or more Chinese manufacturers of mono shocks selling at prices as low as £30, which doesn't actually impress me. Particularly when reading feedbacks that include words "....like being on a pogostick....".

Does anybody know a UK/EU/US manufacturer who can come up with all the accurate figures on their product? Price guide, up to £200 or so.

Any advice on the project, or the product to be used, would be most appreciated.

Tony Norton

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

You know you can get a lowering kit for them for about £100?

https://shop.lustracing.com/products/ktm-390-duke-2024-on-lowering-kit

Or from KTM which also includes front springs which should minimise any changes in geometry. However, listed as "not in stock available soon". With KTM, the definition of "soon" can be somewhat variable.
https://ktmdirect.co.uk/products/duke-25mm-lowering-kit-93312955033
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A100man · World Chat Champion Joined: 19 Aug 2013 Karma :

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

A100man · World Chat Champion Joined: 19 Aug 2013 Karma :

Tony Norton · Nova Slayer Joined: 30 Aug 2007 Karma :

This is getting more complicated than I thought. Mainly because of the lack of engineering information from suppliers. For instance, I've found that there are at least 3 different 'eye' diameters. 10mm seems to be the most common, but there are 11mm and 12mm examples around.

I think I'm going to have to wait until Wednesday, when the bike is delivered, and I can get the shocker off to check it.

Making up a scale drawing from a side-on photo of the Duke it seems I'm going to have to go down from the stock 300mm to 260mm or even 250mm to get a worthwhile reduction in seat height. A shorter shock, however, will mean that the assembly will move upward into the recess in which it sits, which could mean interference with the 'bodywork'.

It's obviously not a matter of whipping out the standard one and whacking in a shorter one. There's nothing quite like having the hardware in your hands.
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Newbie in 2021 at 83. Now the proud holder of an A2 licence. That's far enough! Bikes: YSL 125, AJS Cadwell, Honda Rebel 500, Z300 (to get through A2 Mod 1), MT-07 (Restricted), Eliminator 500.