A fat bloke, a Bomber CR and spring rate calculators

[zac]

So I bought a 7.875x2.25 Bomber CR for the Six but am having a bit of trouble deciding on spring rates. I'm putting in 120kg for rider weight and 170mm travel and the Cyclinic calculator is giving me 800lb whereas the Fox one is anywhere from 700 (30% sag) and 800 (25% sag).

The current shock is one of those DNM RL cheapies and sits at about 50% with 200psi in it. I'm not too concerned about running 30% sag as I'm more of a cruise down the hills than pedal madly up type, but I don't want too much sag either cause it doesn't lock out and from memory there's a bit of pedal bob. I don't know how much bob I'll be able to tune out with the compression adjustment if any as the last coil shock I used was an 03 Vanilla R.

Does anyone have any input re spring rate calculators with regards to how accurate they might be? I get it's going to be a feel thing but I've read some of the results can be not quite right and I'd rather not have to buy twice...

 

[teK--]

You'll end up buying 2-3 springs

 

[yuley95]

So I bought a 7.875x2.25 Bomber CR for the Six but am having a bit of trouble deciding on spring rates. I'm putting in 120kg for rider weight and 170mm travel and the Cyclinic calculator is giving me 800lb whereas the Fox one is anywhere from 700 (30% sag) and 800 (25% sag).

The current shock is one of those DNM RL cheapies and sits at about 50% with 200psi in it. I'm not too concerned about running 30% sag as I'm more of a cruise down the hills than pedal madly up type, but I don't want too much sag either cause it doesn't lock out and from memory there's a bit of pedal bob. I don't know how much bob I'll be able to tune out with the compression adjustment if any as the last coil shock I used was an 03 Vanilla R.

Does anyone have any input re spring rate calculators with regards to how accurate they might be? I get it's going to be a feel thing but I've read some of the results can be not quite right and I'd rather not have to buy twice...

What frame is it (sorry, I’m not getting it from your reference to ‘the six’). Manufacturers sometimes have a recommendations as it depends on leverage ratio as well as weight and travel.

 

[zac]

Sorry, it's an '07 Norco Six...

 

[zac]

You'll end up buying 2-3 springs

Yeah, I figured that, just trying to avoid buying too many...

 

[oldcorollas]

"a" reference point with numbers...

Fox DHX 3 Federberechnung 90kg Norco Six

Hallo, bin über die Suchfunktion nicht wirklich weiter gekommen, liegt vielleicht auch daran dass ich eher der Einsteiger bin und ich mit diversem Fachchinesisch mich noch etwas schwer tu. Hoff deshalb auf eure Hilfe. Daten Bike Norco Six 2 Dämpfer Fox DHx3 Kampfgewicht all incl 90kg (ja ich...

www-mtb--news-de.translate.goog

90kg and 600-650lb (hopefully for 169mm and same geo..)
30% more weight = 800lb?

https://www.marzocchi.com/pages/spring-calculator splits it at 759lb

how many springs options are there at that end of the rates?
https://cyclinic.com.au/products/fox-racing-shox-coil-spring-steel-2-0-2-5-stroke 650, 700lb, then 800lb
https://www.marzocchi.com/products/steel-shock-spring?variant=31281358700646 650, 700lb, then 800lb

does that linkage have two shock mount points?

 

[zac]

"a" reference point with numbers...

Fox DHX 3 Federberechnung 90kg Norco Six

Hallo, bin über die Suchfunktion nicht wirklich weiter gekommen, liegt vielleicht auch daran dass ich eher der Einsteiger bin und ich mit diversem Fachchinesisch mich noch etwas schwer tu. Hoff deshalb auf eure Hilfe. Daten Bike Norco Six 2 Dämpfer Fox DHx3 Kampfgewicht all incl 90kg (ja ich...

www-mtb--news-de.translate.goog

90kg and 600-650lb (hopefully for 169mm and same geo..)
30% more weight = 800lb?

https://www.marzocchi.com/pages/spring-calculator splits it at 759lb

how many springs options are there at that end of the rates?
https://cyclinic.com.au/products/fox-racing-shox-coil-spring-steel-2-0-2-5-stroke 650, 700lb, then 800lb
https://www.marzocchi.com/products/steel-shock-spring?variant=31281358700646 650, 700lb, then 800lb

does that linkage have two shock mount points?

It does, for approx 150 and 170mm. The Fox tool says 700 for 150 and 800 for 170, but the difference for both springs is like 3% in sag, and the 150 setting slackens the front to the point where the fork does weird things. I do have a 130 fork I could throw on to potentially balance it, but I do like the Z150...

Thanks mate, appreciate the link. I might go ahead and order the 800 to be on the safe side - I guess I'd rather it be a little less plush than bottom it out too often, and if (when!) I lose weight I'll grab a 700...

 

[oldcorollas]

It does, for approx 150 and 170mm. The Fox tool says 700 for 150 and 800 for 170, but the difference for both springs is like 3% in sag, and the 150 setting slackens the front to the point where the fork does weird things. I do have a 130 fork I could throw on to potentially balance it, but I do like the Z150...

Thanks mate, appreciate the link. I might go ahead and order the 800 to be on the safe side - I guess I'd rather it be a little less plush than bottom it out too often, and if (when!) I lose weight I'll grab a 700...

keep in mind, i have NFI

 

[zac]

OK, I bought a 700lb spring cause noone seems likely to get an 800 in the near future, fitted the mounts, put it on the bike, snapped the lower mounting bolt through over torquing, replaced the bolt and now I'm a bit stuck... Used to be, the advice for tuning shocks was start with everything wide open (ie minimal damping) but does this still apply with newer shocks (like newer than 2003?) Pretty sure I'm showing my age here...

I remember reading somewhere to start with all the dials about half way and work from there - the only other coil rear shock I've used was a Vanilla R from 2003ish, and the air shocks were either a basic DNM RL or an 05 MC3.1? with 3 stage compression damping (only ever used wide open or lockout), so I'm a bit behind the times with the tech.

I understand that low speed compression is for pedal bob etc, but can anyone suggest a rough starting setting or do I just have it wide open and go from there?

Also, sag seems about right with the 700 but I'm open to swapping it out if I can find an 800 on the near future just to try it

 

[LPG]

Well your bomber rc is basically the vanilla RC from my understanding so your experience may not be alfar off! I'm sure there are updates though.

Back it off to set the sag but then try for something sensible to start your test runs. If you are at or near the max spring I would start the compression a bit over midway and expect to dial it up for your final setting. Rebound will probably be highish to suit the spring but from my experience the bomber rc can go too slow with rebound and pack down if you go too extreme, I'd start lowish and adjust up.

 

[zac]

Well your bomber rc is basically the vanilla RC from my understanding so your experience may not be alfar off! I'm sure there are updates though.

Back it off to set the sag but then try for something sensible to start your test runs. If you are at or near the max spring I would start the compression a bit over midway and expect to dial it up for your final setting. Rebound will probably be highish to suit the spring but from my experience the bomber rc can go too slow with rebound and pack down if you go too extreme, I'd start lowish and adjust up.

Sweet, thanks mate I'll give that a go. Sorry, it was a Vanilla R that I had, this compression gubbins is a bit new to me but your suggestions sound like a good place to start- cheers