Lowering Seat of TS250/1

[Daniel_I]

I've solved most of the little niggles on my 1978 TS250/1. It rides very nicely now. There is now only one major outstanding problem. I am in my later years now and not as flexible as I used to be PLUS I am of short stature (5'0") with shortish legs. I like the bike and want to keep it... but I'd like to lower the seat a couple of inches. The engineer in me reckons it can be done. Change battery height to a flatter wider model. Change Battery holder frame height. Change air intake chamber to a lower but same volume unit... and then reweld frame to suit. Any of your thoughts on this would be appreciated. Many thanks.

[Puffs]

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[Daniel_I]

Thanks 'Puffs'. I could fashion a sheet metal base and cover it with 10mm neoprene. The voltage regulator was replaced when I added the electronic ignition kit about 20 years ago. In addition do you know of any way to lower the rear suspension. Could I just get shorter springs?

[Puffs]

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[Daniel_I]

rotated pic dave

AMZ_rear_suspension-springdamper.jpg (59.1 KiB) Viewed 63335 times

Rear shock length of current spring (unloaded - on centre stand) is 250mm.
Maybe replacing the existing spring with one of the same length but with a thinner wire diameter. This would result in lowering the suspension when under load.

[Jay Bee]

Sorry to be a wet blanket here......
Re the rear suspensiom, the only way to lower the bike effectively would be to use shorter shocks (with appropriate spring and damping rates), although there would be a limit on how much shorter before you rum into mudguard clearance problems, etc. You could work this out by measuring with both shocks removed.
If you followed Puffs' suggestion with spacers in the shocks you will shorten shock travel. With your idea of same length, weaker springs you will likely create a spring rate/damping rate mismatch.
Either way would result in a bike with seriously compromised r. suspension travel - effectively a near-rigid rear end with the shocks spending the majority of their time on the bumpstops.
If you were to carry out the major changes mooted in your first post - and they didn't work - you will end up with a bike that's no use to you or anyone else.

[Puffs]

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[Daniel_I]

I measured eye to eye length of the spring damper and it measured 355mm (as you, Puffs, correctly suggested). The rear tyre is a Michelin M45 16" (as you pointed out) but 3.25 width rather than 3.00. I would think (1) a reduction in tyre profile (if you know of a suitable replacement) coupled with (2)a lowering of the spring dampers would get me an inch or 2 lowering without doing anything too drastic to the bike. I take on board Jay Bee's points about comprehensively stuffing it up if a major frame alteration doesn't work out... so I think changing tyres and rear shocks would be a rather conservative risk free affair which could always be reversed if required. Many thanks Puffs and Jay Bee.

[Puffs]

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[Jay Bee]

Daniel -
There is very little choice (of any profile) of tyres in 16" size.........this makes changing tyres for the only reason of lowering the rear of the bike a non-starter.

I think your best bet is shortening the stroke of the ones you have, as outlined earlier. I'm not sure it would seriously compromise the suspension, but it would rather tailor the suspension to your preferences (which I always do too). Furthermore, it would also be a good opportunity to change the oil in the shocks.

Firstly of course, you have to get them apart......and in view of the age of the bike you'll probably find worn-out components. As far as I know none of these are available as spare parts.
Shortening the working stroke of the shocks effectively also increases the spring preload - this could present a problem if you are quite a light weight.

[Puffs]

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[Daniel_I]

Thanks for all your help, Puffs.
Would it be possible just to replace the rear suspension with something like the one shown in the image? It's just a generic 3rd party suspension unit which measures 300mm. They seem to be available in just about any size (310mm, 320mm, 330mm etc) and I'd pick the one that ensures a reasonable bump gap remains. And they are damping coefficient and stiffness adjustable. Might this be a solution?
Your help is really much appreciated (as is Jay Bee's input also).

[Puffs]

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[parrbd]

You could always heat up the subframe and bend it upwards.