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Choosing the "right" coil spring rate

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#281 · (Edited)
Ah, gotcha.

The spring rates over on Vorpsrung for your weight and travel look like 45 or 40 would be more ideal depending on your preference. Just depends there on how over sprung you feel that the fork is.

I'm 85 kg and would be a 45 as a starting point according to the Vorsprung charts so 40 would make sense or 45 if you are aggressive.
 
#282 ·
Travishutt said:
Yeah rear feels pretty spot on. I am more interested in the optimal front rate, i feel i may be oversprung at 50lbs/in
Click to expand...
Yeah that's a lot firmer than I would suggest. I've had a couple of the same set ups recently and I started them off on a 40lb/in. More aggressive/steeper trails might be better with a 45 and this is consistent with the vorsprung guide. Unless you have particularly unique preferences their chart is pretty damn good
 
#283 ·
Can't say I trust that EXT calculator, I'm around the same weight as you, a couple kg more and on my sb165 with higher progressivity I'm running 425lbs on an 11.6. I have a Smashpot also and I'm running 35lb spring at 180mm travel. I would say my bike feels fairly balanced, no stark contrast between front and rear suspension perfomance anyway, meanwhile you are running a much lighter rear spring and much firmer spring up front... Regardless whether one spring rate or another is correct for you now, whether it be fork or rear, I can pretty much bet the balance of your bike must be off quite a bit. Personally I would up rear spring rate a bit and drop front spring rate by around 10lbs.
 
#284 ·
Travishutt said:
heyo,
Could someone run these numbers through please? having alot of issues trying to get the bike to feel right before states (crashes etc)
2019 Sb150 Large
74kg
Fork - 36 170mm smashpot
Shock - EXT Storia v3 230x60mm 150mm
Wheelbase - 1248mm
Head angle - 64.5
Chainstay - 433mm
Any help will be appreciated
Cheers Trav
Click to expand...
I'm the same weight riding a bike with similar wheelbase and head-angle. 40lb/in is my magic number. 50 is way too firm.
 
#285 ·
My ACS came with 45lb/in, way too stiff. 40 is good. Similar weight.
 
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#286 ·
Danzzz88 said:
Can't say I trust that EXT calculator, I'm around the same weight as you, a couple kg more and on my sb165 with higher progressivity I'm running 425lbs on an 11.6. I have a Smashpot also and I'm running 35lb spring at 180mm travel. I would say my bike feels fairly balanced, no stark contrast between front and rear suspension perfomance anyway, meanwhile you are running a much lighter rear spring and much firmer spring up front... Regardless whether one spring rate or another is correct for you now, whether it be fork or rear, I can pretty much bet the balance of your bike must be off quite a bit. Personally I would up rear spring rate a bit and drop front spring rate by around 10lbs.
Click to expand...
35lb Spring? don't you find it's just way too soft?
I can nearly use 85-90% travel on the 50lb spring just bouncing it around in the carpark
 
#287 ·
Travishutt said:
35lb Spring? don't you find it's just way too soft?
I can nearly use 85-90% travel on the 50lb spring just bouncing it around in the carpark
Click to expand...
My calcs put him on a 40lb/in. Bike geometry has a big effect on front/rear weight distribution too.
 
#289 ·
Travishutt said:
Hey Dougal
The storia has a 375 spring, and the smashpot is 50lbs/in
However the storia feels like it rebounds faster then the smashpot
How may this be? the frequency of the fork should be slightly faster
Click to expand...
If they're both wound right out it would take a very low leverage bike to have a 375lb/in rear running at a faster frequency than a 50lb/in front.
 
#290 ·
Travishutt said:
35lb Spring? don't you find it's just way too soft?
I can nearly use 85-90% travel on the 50lb spring just bouncing it around in the carpark
Click to expand...
I wouldn't say it's 'way' too soft, it's on the plusher side yes, but I feel the bottom out control of the Smashpot does it's job...my bike also has a slack 63.5 head angle and I've noticed trying other bikes in comparison I need to run it a bit softer for the same level of compliance and also get my weight more actively over the front...have to say I'm not sure I'm sold on these new long reach slack head angle bikes for anything other than the steepest terrain...they are very stable and feel much safer but for more mellow local trails the front end can feel a bit unweighted, less direct and less plush. Trouble is I sometimes find if I focus to activel weight the front on these mellower trails the rear end can skip a bit and lose traction, I know most say these longer reach bikes allow more movement on the bike without upsetting the balance but I find on mellower terrain the opposite, I'm in a constant battle trying to either weight the front or the rear...maybe I need to play around with bar height and stem length a bit more because I did notice just dropping bar rise and shortening bar width made a big difference to fork feel in a good way, but on the other hand I prefer a high rise and wider bars for control and body position on steep stuff. I do personally feel goemetry plays a massive role in how we percieve our suspension is working, the shocks may be spot on in a lab setting or certain type of terrain but in reality there is a lot more variables. A shock and fork tuned for the same rider weight, travel and linkage kinematics is not going to feel the same on a bike with steep head angle, short reach and long stays as it will a slack head angle, long reach and short stays all else being equal imo.
 
#293 · (Edited)
PepeTheNoodle said:
87kg
WB 1269
CS 439
HTA 64

170 front travel. 146mm rear travel on a 205x60 shock.
Click to expand...
I ran out of time to do calcs on the website and launched a few calculators.
We've recently redone these.

There used to be a simple, free, calculator with fixed inputs other than weight and an advanced, paid, calculator for $NZ20 where every input can be changed.

To better fit with what customers needed, we've changed this to three calculators:
1. Simple and free fork calculator. This is the same as the old calculator but only forks now. It no longer has the rear shock spring-rate in it because there was too much variation for a simple calculator: Bike Spring Rate Calculator - Simple - Front Spring Only (Shockcraft) | Shockcraft
2. Advanced spring calculator. This is the same as before Bike Spring Rate Calculator - Advanced - Front & Rear Springs (Shockcraft) | Shockcraft
3. Advanced rear shock spring calculator. This is the advanced calculator but only gives you rear shock spring-rates. It is half the price of the full advanced calculator: Bike Spring Rate Calculator - Advanced - Rear Spring Only (Shockcraft) | Shockcraft

These can be found in our "online and download" section: Online & Download - Tools | Shockcraft or in the technical spring rate calculators: https://www.shockcraft.co.nz/technical-support/calculators-195/bike-spring-rate-calculators

We also have more going on behind the scenes with a super-advanced calculator we call the "Fortune Teller".
This has about 5 years development and is used internally. In addition to the spring-rates it gives me damper rates for front and rear compression and rebound.
It now has three riding brackets in it:
  1. Sport is where all the above results fit. It is for fast and aggressive riding but won't beat the crap out of you.
  2. Race and Rowdy is a step up in frequency and spring-rate. It will give more feedback and exhaust you for extended normal riding.
  3. Extreme is what the name suggests.
 
#295 ·
Guys i would love if someone can help with spring rate for my shock CCDB coil gen 1. Commencal Supreme DH v2, single pivot Fork travel: 208 mm HA: 64° Wheelbase: 1200 mm Rear travel: 190 mm Ete: 241 mm Stroke: 76 mm Chainstay: 450 mm Rider weight: 110 kg Currently running 550 lb spring but it feels like it should be a bit more stiffer, feels like i can bottom it out riding on flat.
 
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