 You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
I'm finding it difficult to get the suspension dialled in on my new bike (2021 commencal clash). Yesterday I was riding big and steep dirt jumps and the bike felt a little unpredictable, often getting the sensation of being stuck in the air (aka. dead sailor) and often pushed forwards. I don't think this is a jumping technique issue as I have a long history of BMX riding and this never used to happen on my previous bike on the same jumps, a YT capra 29er with coil shock.
Last night I took some slow motion videos compressing the suspension at home so I could see the balance between my front and rear suspension. I'm not sure if this is relevant or not to what I'm feeling out on the trail but I can see that my rear suspension compresses quicker at first, and then the fork follows and the bike dives forwards - it's subtle but visible. My rebound settings are how i'd usually run them and this seems controlled. I have a theory the issue could be due to the rear being very progressive and hitting the wall of progression whilst the fork continues to dive.
The rear super deluxe shock has 3 factory fitted tokens on a progressive frame linkage. I could experiment by reducing the amount of tokens in the rear shock but I'm already using full travel at the recommended 30% sag. My fork is already at a higher pressure than recommended settings for my weight and with quite a bit of LSC as I like it to stay up in its travel, but I think any firmer would be too much. I'm waiting on a tool to open the fork and see how many tokens it has in.
I'm thinking my options are:
reduce tokens in rear shock and run higher pressures / less sag;
add tokens to the fork to make it more progressive (maybe also reduce LSC a little) if it isn't already stacked with tokens;
possibly try a Meg neg air can to get more mid stroke in the rear. I'd prefer not to spend money straight away though;
Spend loads of money and get a custom tune.
I may sound like i know what i'm doing with all this terminology but i'm very much an armchair engineer. What would you do?
Link to video:
I'd imagine that in that test the rear will compress first because it's a static test in the house and more of your weight may be over the axel / rear shock.
If you've just changed the bike and carried the settings over from your last bike is there a chance that your rebound needs slowed down a bit. I'm no expert but I thought air shocks were more 'poppy' than coil shocks.
For anyone interested, this has been resolved by drastically altering the progressivity front and rear.
I tested this again while rolling after reading the comment above to see if it was just a stationary effect and it did the same thing, possibly even more pronounced. I tried every reasonable combination of air pressure, compression damping and rebound damping with no luck.
Today my tool arrived to open up the fork and I discovered that the zeb with its huge air volume (read: linear) had zero tokens. Meanwhile the rear shock had 3 tokens on a progressive linkage. No idea why commencal ship it like this.
I've removed all 3 tokens from the shock, running it at 25% sag (previously 30%) and added 2 tokens to the fork. Problem solved in terms of balance.
In isolation I actually preferred the more linear feel of the zeb with no tokens so I may try a megneg for the rear shock to further bring out the mid stroke emphasis at the back and then hopefully remain balanced while removing tokens from the fork again.