vivid 5.1 help

eightdigitword

Hi,

I have a Rock shox vivid 5.1 2010 'A' tune shock. I believe i have the correct spring (350lb) for my weight (90-95kg), i currently have the correct sag (25%) with this set up. my bike (scott voltage FR) has a rear wheel travel of 180mm, with 76mm shock stroke the leverage ratio is 2.37. My issue is that i feel that i am going through my travel too quickly on aggressive runs. should i be using a heavier spring or changing up to a 'B' tune shim stack? Rock shox recommends Tune A: for 2.0-2.4 and Tune 'B' a leverage Ratio and 2.4 - 2.85.

Thanks for any advice

benpinnick

As a rule of thumb, use sring rate and preload to control how much travel you use, and damping to control how you use it. When you say too quicky - is that that the bike is bouncy, or continously bottomed out?

eightdigitword

Thanks for the response,

Its not bouncy, it tracks well over big and small bumps, its set for low pedal bob and sits well in berms. I rarely feel the sensation of it bottoming out during drops/big hits but at the end of some tame runs I'll see that at some point it has bottomed out. Over all the shock feels excellent but i feel like it should take more effort to get it to the end of its travel.

benpinnick

Sounds like a too soft spring - ratio effects weight required for the spring - where did you get the spring weight from? Is it stock RS weights or custom for the bike? I think going up a compression tune will make the shock feel harsh. What I think you need is a heavier spring, with less preload. If you did change the spring you should consider reducing the LS compression to compensate, otherwise it will feel less sensitive over the smaller stuff.

eightdigitword

That all makes sense.

The shock is an oem unit off a new Makula and came with a 350lb spring fitted. Looking at online (TF) spring calcs they all recommend a 350 for my weight on a 180mm travel bike with 76mm stroke (Voltage has a single pivot) I left the spring on as it seemed to be the recommended size.

I'll try a bigger spring, should i go for a 400? too much?

Thanks again for the advice, its confirmed what i had suspected.

benpinnick

Its a bit of a hobson's choice IIRC. You'll struggle to get a 375 spring, so yeah, 400lbs and see how you go. You're close to the limit on the 350 spring (I did the calc on TF) and if you want a firmer ride, thats the way to go I think.

eightdigitword

400lb ordered. will see how i get on.

Cheers.