You know that little switch on your clutch mech? That magic little mute button? Well does that clutch affect your suspension?
I had a hunch that the clutch on my mech was inhibiting the initial movement of my rear suspension. We already know that anti-squat (pedalling) and anti-rise (braking) affect the suspension ability to do its job properly. So it is only a small leap of logic to assume that the clutch inhibiting your mechs movement, (thus affecting chain growth) is adding to that mix.
I’d proposed this question a few times and was always met with two responses;
“There are bigger influencing forces, like rocks on the trail! The clutch exerts such a small amount of force that it makes no difference!”
So with no way to prove or disprove my hypothesis the debate always ended there, that is until I had an extended loan of a Shock Wiz. The Shock Wiz is a suspension setup aid, it plumbs into the air valve of air forks and shocks, monitors them on the trail and offers setup advice and feedback. With the latest update to the app, this little unit now offers a far more nuanced tool for suspension tuning. It also offered the opportunity to experiment and get some data to further my curiosity on the subject.
Time for the science bit.
The experiment was simple, I had gotten my Shock Wiz score to 88% and I was feeling pretty happy with how it was all feeling. I would do a control run of a fairly typical piece of natural Scottish single track, then again with the clutch switched off. This direct comparison would show if the Shock Wiz detected a difference in the shocks behaviour.
The test track was a lovely little ribbon of prime condition singletrack on the southern edge of Aberfeldy. Comprising of fast and pedally sprint sections, drops and root matrices, so providing a good variety of trail conditions to test on. After a few runs it was time to consult the app and see if the Wiz had noticed a difference.
My prediction was that the Shock Wiz score would decrease and the low speed compression would need increased by a few clicks and maybe a few more PSI in the air spring. My thinking being that the clutch would inhibit rider induced movement and would be more active to small bump input.
So in short, yes the derailleur clutch does impact the suspension,
Whilst the suggestion after the first run was that with the easier breakaway more air pressure was required, however after successive runs it settled back to the green. So, my prediction was partially right, the compression was affected, but it was in the high-speed over my predicted low. So in short, yes the derailleur clutch does impact the suspension, now the question was, how much of an impact does it actually make?
Well the initial suggestion, with the mech activated was that the high-speed was far too firm, listed fully in the red. So by the apps measure, it needed adjusted by three or more clicks softer. Now the Cane Creek Inline, has an adjustment range of four full turns on HSC. So if we take one half turn to equate to one click of adjustment, three or more clicks is a significant tweak that the app is looking to make.
However with the clutch turned off the app was only looking to make an adjustment of one to two clicks, so maybe a single half turn. That is more or less in the right ball park in my view.
Something that I did find interesting, is the lack of a braking shudder feedback that I experienced with the clutch turn off. With the clutch on, when I was at full chatt through a rock garden I had significant shudder from my rear brake. My reckoning was that this was my shock and clutch fighting it out due to brake jack. With the clutch no longer fighting the HSC the shudder didn’t occur. Shock was able to do its job and the bike just monster trucked along.
Did it make a difference to what I experienced as a rider? In some circumstances.
Was the bike louder? Well, yes.
Did I drop a chain? No, I have a chain guide and narrow wide front chain ring for that.
Did the the app measure an improvement with it turned off? Yes, the tuning score improved by 5%.
Will I run the mech with it switched off form now on? In some circumstances, yes I will.
Will this be a definitive answer to this question on STW? HAHAHAHAHAHAAHAAA, sorry was that a serious question?