Rear Spring Rate for 2010 FE390 and 98kg rider suited up

fizz · Jan 2, 2011

I weigh 98kg with all my riding gear on, and ride predominately rutted single track.
At 16 hrs on the bike, today I checked static and rider sag:
Static Sag was exactly per manual at 35mm. This is spot on.
Rider Sag is 116mm (11mm over 105mm recommended ) standing up and 128mm sitting down (23mm over 105mm recommended). The manual says rider sag should be 105mm.

The manual says if:
weight of rider 75-85kg ---> 72 N/mm spring required and this is supplied with the bike.
weight of rider 85-95 kg ---> 76N/mm rear spring required.

Question:

As I am 98kg with all bike gear on, do I just buy the 76N/mm spring that has an upper range of 95kg rider as it is 'near enough to my 98kg weight', or should I go for the next level of spring up as I exceed the weight range by 3kg over the 95 upper spring limit- but this spring isnt specified in the manual - what is it?

Thanx in advance
Fizz

Taffy · Jan 2, 2011

i weigh 95 plus kit so a bit more.

was 76 now 84. preload is 8mm and evev then I haven't made the 105 and still 107mm. so i reckon you can't be far off at 84. jMHO

regards

Taffy

fizz · Jan 4, 2011

I have removed the rear shock before. How easy is it to fit a new rear spring to the shock, can I do it at home or is it definitely take to a shop job?
If I can do it in my garage, what are the steps?

Thanx in advance
fizz

bowser · Jan 4, 2011

do it at home, it will take you all of 10 minutes.
remove the shock, wind all the preload off the spring plus some to allow the sping to move up around 1cm or more. pull the bottom spring seat up and you will find a circlip, remove it and the bottom spring seat then the spring. Reinstall in the opposite order.

I would say either a 8.4 linear spring or P20 racetech progressive spring (that's what i'm now using)

fizz · Jan 10, 2011

I have just fitted a new 80nm\250 rear spring (stock is 72nm\250) and tested it weighted up as if going for a ride (98kgs).

Spring Preload : approx 8mm
Static Sag : 35mm <======= as per manual

Rider Sag (sitting on seat) : 114mm <======= 9mm over the majic 105mm per manual
Rider Sag (standing up) : 112mm <======= 7mm over the majic 105mm per manual

So what do I do now? If I tighten the spring preload colar, static sag will be reduced but will get a better rider sag near 105. It seems to be a see-saw, changing one for the better changes another for the worse. If I increase preload I reduce rear travel I assume so that would be a bad thing?

What do I change if anything? - typically I ride slow ,rutted, rocky single track.

Regards
fizz

bowser · Jan 10, 2011

leave it at that and try it before you change anything.Then try 5mm rider sag changes to 90 or 95mm and take notes on which you like best and why

Taffy · Jan 10, 2011

I always set the shock to how it feels. change the fork height to get it all together so drop the clamps down the forks for example.

to me race sag is more important than rider sag. race sag means the handling of the bike is right. rider sag doesn't. but that's just my opinion....

two people said a heavier spring yet you went for a lighter one and then ask us what you should do next? was that the brightest thing you ever did in your life? you could always pull the spring off before it's marked and send it back?

regards

Taffy

fizz · Jan 10, 2011

Taffy said:
...two people said a heavier spring yet you went for a lighter one and then ask us what you should do next? was that the brightest thing you ever did in your life...

Thanks for the input.

As I weigh 98 kg with gear (and 85kg without) your earlier post you stated 'i weigh 95 plus kit so a bit more'... so I assumed I need a lighter spring than you stated as I am 10kg lighter than you. The manual itself stated a 76Nm spring up to 95Kg rider, so I assumed I just need only the next spring rate up from that which is 80Nm. I also put on 2 kgs over xmas that I will be losing soon :lol: .

The 80Nm spring should be fine, as to get rider\race sag I carried 3 litres of water in the backpack - (its HOT where I live) and full tank of full (8.5 litres), so after 4 hrs riding I will lose 5kgs in weight as me and the bike drink, so it is probably the right spring rate most of the time, and MUCH btter than the 7.2Nm the bike came with.

I'll increase the preload to get a better rider sag setting.

Thanks again.

Regards
fizz

Regards
fizz

Taffy · Jan 10, 2011

....and by the time you've broken the spring in the sag numbers will be worse....so you'll be back where you started.

whatever

regards

Taffy

Derbo250x · Jan 18, 2011

fizz said:
I have just fitted a new 80nm\250 rear spring (stock is 72nm\250) and tested it weighted up as if going for a ride (98kgs).

Spring Preload : approx 8mm
Static Sag : 35mm <======= as per manual

Rider Sag (sitting on seat) : 114mm <======= 9mm over the majic 105mm per manual
Rider Sag (standing up) : 112mm <======= 7mm over the majic 105mm per manual

So what do I do now? If I tighten the spring preload colar, static sag will be reduced but will get a better rider sag near 105. It seems to be a see-saw, changing one for the better changes another for the worse. If I increase preload I reduce rear travel I assume so that would be a bad thing?

What do I change if anything? - typically I ride slow ,rutted, rocky single track.

Regards
fizz

Good show not getting into a quible

I hate oversprung bikes more than undersprung ones, so I would of erred on the softer side too. What do you think of your current settings? Do you still have good chop compliance with bigger hit response.....or does it all suck wind and you wasted a bunch of coin?
Derik

Rear Spring Rate for 2010 FE390 and 98kg rider suited up

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