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  1. #1
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    Clutch effect on suspension?

    I read a comment on another forum about the derailleur clutch having an effect on the small bump sensitivity. Being less.
    At first I thought it was splitting hairs in 4, but after having think about it, it could make a bit a sense. So I made the test by setting my sag with and without the clutch on my XT engage.
    I could swear that I was ''floating'' more around the sag point without clutch. Meaning more sensible, but does it translate in a perceptible difference when riding? Discussion open.

  2. #2
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    Your going to notice a tire pressure change way more depending on suspension design. The more chain growth you have obviously the more effect their will be to the point you might actually be able to notice it. Also depends on how tight you have your clutch set. On the better suspension designs I think even the mention of it is splitting hairs a lot more than 4 ways lol.

    The RD still moves with clutch on, just stiffer to move. Your going to get annoyed with how it shifts long before you actually notice the effects on suspension. And you'd be running that clutch rather tight as well.


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  3. #3
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    I've actually noticed the difference between clutch on or off on my Spark...but I can typically feel things. Feels like a tad more compression.

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  4. #4
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    Interesting point. The rear suspension is constantly working the clutch. I wonder how that affects wear.
    Do the math.

  5. #5
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    Well seeing as that is the design point of the clutches originally, deal with chain slap/drops on FS bikes I'd say it's within "manufacturer specified service life".

    I don't even use the clutch usually myself since I'm on hardtails. Sram doesn't turn on and off so have no way to know how that matters on my fat bike. But seeing as I beat the crap outta it (doesn't see actual trails as much as making its own) and chain slap I don't notice if it happens.

    My new plus bike I anticipate it being beat harder than my 29er I replaced (I set it up but half the time I was off), so I may set the clutch up so it helps but doesn't annoy me with the stiffer shifting.

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  6. #6
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    It's the restriction of "chain growth" that can be designed into certain suspension setups, the poe in the hub can also interfere depending on how much pedal kickback is there for a specific gear ratio
    ...

  7. #7
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    Quote Originally Posted by J: View Post
    It's the restriction of "chain growth" that can be designed into certain suspension setups, the poe in the hub can also interfere depending on how much pedal kickback is there for a specific gear ratio
    Good point. With higher POE, it's ''glide the clutch'' sooner and more often.

  8. #8
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    Quote Originally Posted by Lone Rager View Post
    Interesting point. The rear suspension is constantly working the clutch. I wonder how that affects wear.
    Purely for demonstration or tuning purposes, the simplest way to watch what is happening at the pedals as the suspension cycles, just remove the shock spring (or air pressure) and bottom the suspension when in high-high gears and bottom it again after you change gears to low-low. You'll see the pedals reverse when the chain tugs on the suspension and that's where you'll feel it on your feet when your body weight is on the pedals as the suspension cycles.
    ...

  9. #9
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  10. #10
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    Fortunately, the Shimano rear derailleur clutch assembly is easy to service. And, it does require service.

    The video says it all.
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  11. #11
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    Hum, OP, interesting thread. I only recently swapped to 10spd from 9spd Shimano to get the benefits of the clutch, however, I have noticed that the suspension does feel harsher since about the change, but never thought it could be the clutch, but now you have me thinking, figured the shock needed a proper service after a 3 year life span with basic service

    I will give it a test and ride a few sections of trail with and without the clutch engaged and get back to this thread with my findings, I for sure am very interested to see if maybe this is my "sudden": cause for the harsher ride feel.
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  12. #12
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    Quote Originally Posted by LyNx View Post
    Hum, OP, interesting thread. I only recently swapped to 10spd from 9spd Shimano to get the benefits of the clutch, however, I have noticed that the suspension does feel harsher since about the change, but never thought it could be the clutch, but now you have me thinking, figured the shock needed a proper service after a 3 year life span with basic service

    I will give it a test and ride a few sections of trail with and without the clutch engaged and get back to this thread with my findings, I for sure am very interested to see if maybe this is my "sudden": cause for the harsher ride feel.
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  13. #13
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    I don't care how crappy the clutch makes the rear feel, still a hundred times better than the chain slapping all over the place IMO.
    Niner Jet 9 RDO, Scalpel 29, XTC 650b, 04 Stumpjumper FSR Pro, Trek Rigid SS - No suspension, no gears....no problem

  14. #14
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    I hear what some have said about the possibility of the clutch creating some noticeable effect on the rear shock compliance.

    When we factor in all of the various contributions that could have some perceivable effect on the rear shock and the forces involved, I'm not subscribing to the theory that the friction on a derailleur clutch would have any perceivable impact on our ability to notice. That's my take.
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    Broke my derailleur a while back at the top of a run I'm really familiar with. Took off the chain and descended. Oh man, it felt like a new bike. The rear end was far more active and plush and it wasn't subtle. This was on a Nomad 3 with the monarch plus. I'd always been disappointed with that shock on that bike but it felt amazing without a chain.

  16. #16
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    Quote Originally Posted by Cleared2land View Post
    I hear what some have said about the possibility of the clutch creating some noticeable effect on the rear shock compliance.

    When we factor in all of the various contributions that could have some perceivable effect on the rear shock and the forces involved, I'm not subscribing to the theory that the friction on a derailleur clutch would have any perceivable impact on our ability to notice. That's my take.
    Pretty much this
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  17. #17
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    Well then damn we should go back bushing instead of bearings in pivot points. And those who claim gains in small bump sensitivity with a change to needle bearings in shock mounts must be full of it too.

    It's not a theory to me on my bike, it was an observation when I went to a clutch der.

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  18. #18
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    Theory? Observation?

    Yes, the cage will pivot when the suspension is compressed. That's observable.
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  19. #19
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    Quote Originally Posted by zephxiii View Post
    Well then damn we should go back bushing instead of bearings in pivot points. And those who claim gains in small bump sensitivity with a change to needle bearings in shock mounts must be full of it too.

    It's not a theory to me on my bike, it was an observation when I went to a clutch der.

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  20. #20
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    Like anti-squat values of frames... i believe this only comes into play when the chain is under tension. Seeing as the clutch is working on the non-tension side, I do not believe the clutch will have any affect. Same goes for chain forces in general. This only happens while the cranks are turning, there is very little chain effect on the drive train under non-pedaling situations. You could obviously argue that there is something there... but it's likely so insignificant that you would not be able to perceive it.

    As others have suggested... I think a lot of us have forgotten to put our clutch on before starting a ride or after changing a flat trail side. Typically, the only time you would notice is when you get back to the ride start point, or drop a chain.

  21. #21
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    Quote Originally Posted by TwoTone View Post
    I'd be willing to bet you that if you had a blind test where you didn't know if the clutch was on or off you wouldn't be able to tell.
    I'd be willing to be that I would...I already know what the difference between on/off feels like. I noticed it after switching to a clutch der and I wasn't looking for it either. I just happened to notice that it felt like small bumps were more noticeable with the clutch on. My Spark w/ meh Float CTD is already a little firm when it comes to small bump sensitivity so a slight increase in compression resistance to me can be felt. I'm not saying it is major, it is slight, but enough for me to feel. Now I may or may not be able to tell on other frames, but it would be interesting and fun to try.

    Quote Originally Posted by minimusprime View Post
    Like anti-squat values of frames... i believe this only comes into play when the chain is under tension. Seeing as the clutch is working on the non-tension side, I do not believe the clutch will have any affect. Same goes for chain forces in general. This only happens while the cranks are turning, there is very little chain effect on the drive train under non-pedaling situations. You could obviously argue that there is something there... but it's likely so insignificant that you would not be able to perceive it.

    As others have suggested... I think a lot of us have forgotten to put our clutch on before starting a ride or after changing a flat trail side. Typically, the only time you would notice is when you get back to the ride start point, or drop a chain.
    When the suspension compresses the der cage will be pulled by the chain rotate against the cage's spring which adds a small amount of resistance to suspension compression. Adding a clutch to that will just add additional resistance. The holy grail of small bump sensitivity seems to revolve around reducing as much friction and resistance in the suspension as possible. Well that clutch I just turned on is doing the opposite of that.
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  22. #22
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    As a curiosity, have you serviced and lubricated your derailleur clutch. Have you considered reducing the Friction adjustment bolt to reduce friction torque? How about rear shock adjustment to compensate for your loss of small bump compliance?
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  23. #23
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    There's a lot to consider here. I think most modern 160mm travel trail bikes have chain stay growth in the range of 10-30mm through out the travel. So the chain tension is indeed going to increase, especially near the end of the stroke. The thing is that mtb suspension has some insane shaft speeds. That's one of the things that makes MTB suspension unique over say car suspension. I just don't think that there is enough chain stay growth at the first 50% of the travel for most bikes to have a compelling effect on the suspension performance. I could definitely understand the chain and clutch providing some measurable resistance towards the end of the travel... but for the first half (and likely first 2/3 on most linkages) the shaft speeds would be so great that the chain tension would be a drop in the bucket.

    Now for low speed events... sure, conceptually, the derailleur could have an effect on the suspension... but most bikes have a 2.5 to 3/1 leverage ratio in this part of the stroke, and chainstay growth is negligible at this point in the travel.

    What we're talking about here is the critical damping area or knee. I don't think that particular area under the curve is going to be affected by the clutched derailleur. Also, keep in mind that if your clutch is adjusted properly, it will have some breakaway, sorta like a LSC circuit.

  24. #24
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    Quote Originally Posted by TwoTone View Post
    Pretty much this
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  25. #25
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    ^^^ yepper to both of you.
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  26. #26
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    I think most of problems comes from kickback characteristic of the frame, small bump compliance too, maybe with high cog ta rear gear.

  27. #27
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    Quote Originally Posted by Cleared2land View Post
    Theory? Observation?

    Yes, the cage will pivot when the suspension is compressed. That's observable.
    So I noticed a "clunk" on my new bike , checked pivots...bearings...shock bushings...etc...while off my bike i leaned on the saddle and slowly compressed my shock. I noticed that the chain and rear derailer "tugged " and i felt and heard the clunk. I turned the clutch off and repeated the process. ..no clunk.
    Does this mean...
    1. Clutch needs backing off?
    2. Chain too short?

    Thanks for the help

  28. #28
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    Quote Originally Posted by freeriderB View Post
    Does this mean...
    1. Clutch needs backing off?
    2. Chain too short?
    Perhaps neither.

    Did your chain shrink?
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  29. #29
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    Um no...
    I thought those 2 suggestions made the most logical sense...
    Do you have another possibility?

  30. #30
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    You mentioned new bike. Did you just obtain the bike and notice the 'clunking'?

    You also stated that the clunking went away when you turned off the clutch. If you had not said that, I would have presumed that it was not the derailleur.
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  31. #31
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    Approx 6 rides in...built it up.
    Troubleshooting on and off.
    Everything shifts fine.
    Right...clutch on I feel clunk...off...clunk gone.
    So the tension must be too tight when on...my best guess

  32. #32
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    Shimano Shadow Derailleur? Install it new?
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  33. #33
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    Yes...new xt.. I actually had my lbs size the chain and install shift cable

  34. #34
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    Ok, the LBS did your chain. Do a little search and you can find the techniques for determining proper chain length. I'm too lazy to do it. I've done it an numerous builds. Now that theory is plausible, but I'm not buying that just yet.

    Have you been able to observe the derailleur up closely while compressing the suspension? Watch and feel the cage while repeating the offending action. Anything look 'jerky' or can you feel the clunk?

    Have you considered removing the clutch cover and seeing if you can see anything when the suspension is compressed and the clutch is functioning? This can be a good time to learn a little about the inner workings of a clutch mechanism. A fair number of folks really don't understand how the clutch actually works.

    Second, I would suggest (if youíre comfortable) removing the clutch mechanism (stabilizer) and cam unit and confirming proper lubrication of the clutch band. Several of the new M-785 Shadow derailleurs that I have installed were (in my opinion) deficient in the lubrication department. So, a quick service and all was good.
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  35. #35
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    My fastest run was chainless and brakeless

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