I had occasion to carry a 100kg rider with me today, the rear bottomed out a few times on our B grade roads. Is there a heavier spring for the stock shockie? Or if not how would I go about getting a heavier spring. There is a place called Dumbrel Springs in Wallsend NSW about 40mins away, Would I just drop in with the shockie and say this bike now gets two riders over 100kg on it instead of the 2x75kg riders it was designed for? I need some heads ups so I can talk turkey with spring type people.

HI I take it that your normal setting is on the softest for solo riding. Did you reset to max before riding with your pillion rider. Having ridden 2 up loads of gear on board on rough roads without bottoming out. If you did set on MAX then i think your shock is more than a little tired and a new one is on the cards.

Any coil spring manufacturer worth their salt will be able to tell by measuring the spring diameter, wire diameter and number of turns and make one a bit heavier. It may only need one less turn in the same length or sumptin like that.

G'day Keith, Dumbrells at Wallsend have closed. I have no idea if they still exist or where they are. Cheers Tom

https://suspensionsecrets.co.uk/how-to-calculate-coil-or-leaf-spring-rates/

The clown(ess) and I had a conversation about this on here, but I can't find it.

Thanks Dai that will come in handy, OMG Tom! how could they disso when i need them, but thanks for the heads up. Rick Thanks I also thought they who wind springs did them with a greater pitch and same wire dia, We still have single stage damping on these bikes don't we. Moriati you are closer to the truth than even I expected. I come here cap in hand to advise that I'm on the 3rd of 4 notches for the spring, (oh dear) and 3/4 on the s/h of the shockies dampener. SO I have moved the spring up one more to the top and have adjusted the dampener to hard. Still we are both over the 100kg mark so surely I should get a heavier spring made for it. However I'm yet to read the site Dai put up and discover which works best with springs, but had it in mind that single stage dampening needed single stage springing with just the last quarter of a stiffer stance in springing (basically to handle our whumps mid corner that we especially install in corners here in Oz) to counter that lst little bit.

Lastly the flat bit on the spring wind that acts as a contact as the windings close up. That bits important isn't it? The old Koni I have doesn't have it. It is off the K75, just wondering possibly some spring engineers design these things to not tough when the shockie is bottoming out. Seems an odd thing to do.

You say you have a stock shock and spring on your bike.  If it was original then I would think the shock and the spring are both well past their "best by" dates and should probably be replaced.

There are several sources for aftermarket suspension parts.  I have replaced the shock on my 16V K100 with a YSS unit.  They're very reasonably priced, and the purchase process includes questions about rider and passenger weight, gear, and riding style.  Once you answer the questions they select the shock and spring.  The results were excellent.

Yes .75 that sounds like the path to take. Thanks.

All of this discussion reminds me of the the move from bench seats in cars to bucket seats. They were comfortable, but it depended on the size and weight of your bucket. Get the best combination for your bike.

G'Day Stan. Yes and this old girl handled the one bucket just fine. I'd probably not had an issue if I had upped the spring and dampener rate to highest setting, but I missed it by one setting. Still now it has me wondering about the spring and damper setup, The spring goes from 16mm gap between coils to 3mm over 13 coils and that's way more than the 100mm travel available on the shaft. Also noted no bump stop. Still measuring all the gaps so I can go have a yack with a suspension specialist about whether the coils are supposed to touch at the same time the body reaches the shaft stop. Don't think I'll mention buckets to the suspension bloke though.

It might help if you can post a photo of your shock and spring.  If it is an increasing rate spring the gaps between coils will get progressively smaller going from one end to the other. 

With a progressive spring, the smaller gaps will close before the wider ones gradually making the spring stiffer.

Piccies

On it's highest setting I have 102mm of available spring travel, and 98or100mm of shaft travel. So if everything compresses in a big whump of a bump, I seem to be 4mm out and I'm missing a bump stop. Maybe a 4-5mm spacer would have the springs and shocky closed at the same time. I'll have to check spacings with a proper gauge.

Are you sure the shock is not upside down?

That's an Original Showa and correct mounting.
Keith send it up to RAD shocks in Brizvegas, he will be able to reco it, last I heard $200 and $50 more for a shaft rechrome. Everybody I have heard says only good things about him.

Thanks Rick, yes It could do with a refurb. I am somewhat puzzled by the fact there are no witness marks on the shock body where we bottomed out. bearing in mind I cant find my callipers and am only eyeballing the measurements, The spring must be going spring bound before the shock body meets the nut under the top mount.
I had visions of it shagging the seal in there but without witness marks to suggest it has made contact, maybe the springs have taken the brunt of the fully compressed suspension.

You could try Chivo in Holroyd Sydney. He'd be a bit closer. I've found him to be reliable and reasonably priced.