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Old 11-12-2007, 03:11 PM   #1
BirtDike OP
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Joined: Feb 2007
Location: A Kiwi Living in London
Oddometer: 52
Question Progressive rear spring on 640 Adv???

Next year I'm doing what is probably all of our dream trip, and riding London to Cape Town. I will be riding badly corrugated roads loaded with the usual junk on the back including TTech boxes, cooker, tent, the little carpet I'll pick up in the Moroccan markets etc etc...

Anyway, I rang a suspension expert here today, and asked what he'd recommend in the way of back springs. I figured he'd probably advise something like an upgrade from the 70/260 to an 80/260 - instead, after he'd rung the WP Suspension importer, he suggested that I go for a 70-90 progressive spring.

Firstly, anyone know how the 640 would go with a progressive spring? Does the linkage already make the spring rate progressive with a linear spring?

I figure that the loaded sag of the bike is going to be pretty high with a spring starting at 70 (sorry, I've got no idea what units the 70 is . 70kgs/cm???), and would probably need a fair amount of preload to set it up right - would this create spring bind like it can on a mountain bike? Any other negative effects?

Anyone with any knowlegeable advice as to what I should put on will be really appreciated. I don't want to go fast, I just don't want my shock to blow up in in Timbuktu (literally). FYI - I probably weigh close to 100kgs fully kitted for riding (220 for those who think in old school).

One more thing - is is possible to change the spring from the shock body yourself, just by backing off the preload, or do you need the special spring compressor tool?

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