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  1. #1
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    SB66 makes a "knock" at inflection point - Anyone else?

    Since I got my 66, there's been an annoying knocking/ticking sensation that I feel through the bike.

    I've definitely identified the issue is due to the stop bolt (that bolt at the bottom of the eccentric). When I removed it, it was knock-free. However, the Switch cannot function as intended without this bolt.

    Anyone else out there experiencing this issue? I actually removed the eccentric and placed some padding where the stop bolt hits. It's helped about 25% of the knocking.

    If you don't know what I'm talking about. See the photo below. That little black bolt is what makes the Switch, switch:

    Name:  yeti_sb_66_alloy_mountain_bike_eccentric_kit-s.jpeg
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  2. #2
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    If anyone is interested, I've fixed the issue by adding a small felt pad in the eccentric unit. It's small enough to have no effect on suspension performance, but has definitely damped the knocking coming from the stop bolt. The stroke is now super smooth as it should be, for a $2,000 frame...

    John P, feel free to chime in here:

    SB66 makes a "knock" at inflection point - Anyone else?-529456_101507043382633_501442707_n.jpg
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  3. #3
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    I'm glad you've got a fix but i'm not sure it should be hitting the bolt at all. Haven't heard of that before. For sure my '95 doesn't.

  4. #4
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    Trust me, it's designed to make contact with the stop bolt (not necessarily a "hit").

    If you don't believe me, remove the stop bolt and then bottom out your suspension... Watch what happens.

    Quote Originally Posted by bear View Post
    I'm glad you've got a fix but i'm not sure it should be hitting the bolt at all. Haven't heard of that before. For sure my '95 doesn't.
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  5. #5
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    I've just tested mine, reduced the air pressure and cycled it multiple times through its entire travel and I don't get any knocks either audible or felt.

    Just a quick check my shock eye to eye (centre to centre) measurement is 21.5 cm on the bike un-weighted....

    I believe the bolt is to prevent over rotation of the switch mechanism so it sounds like your over rotating your switch mechanism hence my question about shock length.

    Ask Andrew over on YetiFan he may be able to assist.

  6. #6
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    Quote Originally Posted by RocketMagnet View Post
    I've just tested mine, reduced the air pressure and cycled it multiple times through its entire travel and I don't get any knocks either audible or felt.

    Just a quick check my shock eye to eye (centre to centre) measurement is 21.5 cm on the bike un-weighted....

    I believe the bolt is to prevent over rotation of the switch mechanism so it sounds like your over rotating your switch mechanism hence my question about shock length.

    Ask Andrew over on YetiFan he may be able to assist.
    Very interesting...

    The knock is only noticeable under load. I have to sit on the bike to replicate it. Very noticeable on slower compressions, rather than quick ones.

    It's definitely not shock related. I recently swapped the RP23 for a CCDB and the knock was still there.
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  7. #7
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    Hmm that's really odd and we know that it should not be doing this.

    If you'd not said anything id have been asking if your bearings are ok
    and that you've not over/under torqued your pivot bolts. So presumably
    they are all perfectly smooth?
    but you say your fix has resolved the issue so it can't be this....
    I presume there is wear under your pad where the stop has been hitting?

    Its definitely a "Stop" (i.e. end of travel) and is listed as such in the SB66 manual on P28:
    http://www.yeticycles.com/pdf/manual...al_SB66_LR.pdf
    18 300030234 bolt stop m12x1.25x10mm 1
    19 300030235 bumper stop 1

    Knew i'd seen it somewhere but this thread discusses what the stop bolt is for..
    YETIFAN.com FORUM - SB66C Bearings and lock screw

  8. #8
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    To update this, I spoke with Yeti and will be sending the frame back to them for examination. They were firm on the fact that there should be no knock whatsoever... *Phew* My LBS will be sending it back to them come Monday, and I hope to get this issue resolved in a couple weeks. Yeti advised they have really quick turn-around times for warranty claims.

    FWIW, here's a video of my frame's knock (the couple louder hits are just the suspension bottoming out). So, imagine this while you're riding. Quite distracting as I feel it on all contact points of the bike:

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  9. #9
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    Quote Originally Posted by RocketMagnet View Post
    Hmm that's really odd and we know that it should not be doing this.

    If you'd not said anything id have been asking if your bearings are ok
    and that you've not over/under torqued your pivot bolts. So presumably
    they are all perfectly smooth?
    but you say your fix has resolved the issue so it can't be this....
    I presume there is wear under your pad where the stop has been hitting?

    Its definitely a "Stop" (i.e. end of travel) and is listed as such in the SB66 manual on P28:
    http://www.yeticycles.com/pdf/manual...al_SB66_LR.pdf
    18 300030234 bolt stop m12x1.25x10mm 1
    19 300030235 bumper stop 1

    Knew i'd seen it somewhere but this thread discusses what the stop bolt is for..
    YETIFAN.com FORUM - SB66C Bearings and lock screw
    I doubt its anything to do with the pivots/axles/bearings. When the stop bolt removed, the thing was damn knock-free. But after a few test rides, the felt pad started to pack in and we're now back to square one.

    I also tested the bike with less torque on the axles, same issue.
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  10. #10
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    To update this thread...

    I simply contacted Yeti, and they worked with my LBS on getting the front triangle + eccentric swapped. The total turn-around time for this process was... 7 days! And I live in Canada too!

    My LBS shipped it out on Tuesday. Yeti received it on Thursday. Shipped frame with new 2013 front triangle + eccentric the following day. Received my bike back today, the following Monday. I've just finished building it back and behold, my bike is finally knock-free!

    Thank you Yeti. This has been the absolute best customer service I've ever had.

    SB66 makes a "knock" at inflection point - Anyone else?-485594_118041615062509_1805473749_n.jpg
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  11. #11
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    Re: SB66 makes a "knock" at inflection point - Anyone else?

    I had the same issue on my SB66, and that was due to using a SRAM Type 2 RD.

  12. #12
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    If that's a RockGuardz down-tube protector its on upside down Thimk.

    Yeti SB66 RockGuardZ - YETI

    Really cool Yeti sorted it out for you, they are really good that way.

  13. #13
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    SB66 makes a "knock" at inflection point - Anyone else?

    Quote Originally Posted by hssp View Post
    I had the same issue on my SB66, and that was due to using a SRAM Type 2 RD.
    I am about to install a type 2 RD, was there a fix for you or do I need to sell it?

  14. #14
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    Quote Originally Posted by RocketMagnet View Post
    If that's a RockGuardz down-tube protector its on upside down Thimk.

    Yeti SB66 RockGuardZ - YETI

    Really cool Yeti sorted it out for you, they are really good that way.
    LOL! Thanks for pointing that out. I've just fixed it.

    Yes, and they were very easy to deal with it.
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  15. #15
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    Re: SB66 makes a "knock" at inflection point - Anyone else?

    Quote Originally Posted by pcemkr View Post
    I am about to install a type 2 RD, was there a fix for you or do I need to sell it?
    It's not a bug, it's a feature. Thing is, as you compress the suspension, the clutch is holding back, but the cage is flexing. At one point, the force from the chain stretching is becoming greater than the clutch force, and it is the release of the clutch that gives the knocking sound. Not noticable when riding, though.

  16. #16
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    SB66 makes a "knock" at inflection point - Anyone else?

    Good to know, thanks for replying.

  17. #17
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    SB66 makes a "knock" at inflection point - Anyone else?

    I had this same issue and yeti sent me a replacement rubber bumper for the stop bolt. Works as good as new know.

  18. #18
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    same issue on the carbon version

    Quote Originally Posted by richie101 View Post
    I had this same issue and yeti sent me a replacement rubber bumper for the stop bolt. Works as good as new know.
    I have a similar noise on the carbon version that I just purchased. Will show it to my dealer when he is back, but I have the impression it comes from the pivots/axles/bearings that could be too tighten. The noise appears half way when compressing the shock and even 2-3 times during the travel, so it seems like the issue is more on the pivots/axles/bearings that do not move freely.

    I will have a closer look tomorrow, if someone has an idea...

    thanks

    Gerome

  19. #19
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    Quote Originally Posted by french_yeti View Post
    I have a similar noise on the carbon version that I just purchased. Will show it to my dealer when he is back, but I have the impression it comes from the pivots/axles/bearings that could be too tighten. The noise appears half way when compressing the shock and even 2-3 times during the travel, so it seems like the issue is more on the pivots/axles/bearings that do not move freely.

    I will have a closer look tomorrow, if someone has an idea...

    thanks

    Gerome
    Hi,

    I did some tests and indeed, it was the derailleur which was doing the noise. Nothing wrong then on the shock or the frame.

    Gerome

  20. #20
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    If you're running XX1, then I would bet it's the derailleur, unless you've done the mod.

  21. #21
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    Quote Originally Posted by Simplemind View Post
    If you're running XX1, then I would bet it's the derailleur, unless you've done the mod.
    Yes, I am running XX1, which mod are you talking about ?

    Thanks.

    Gerome.

  22. #22
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    Quote Originally Posted by french_yeti View Post
    Yes, I am running XX1, which mod are you talking about ?

    Thanks.

    Gerome.
    It's not really a mod per se, just an adjustment/lube application. Here is a link that covers much of the issue.

    The way I isolated the problem to the derailleur was to lock out the derailleur using the pin, ie giving slack to the chain, then compressed the suspension, and viola...no clunking.

  23. #23
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    Hey guys. Gonna open this thread back up. I assume I'm having the same noise issue. It's really bad under hard hits and it's really loud. I took everything off my bike except the wheels to troubleshoot it and if I pick up the rear end and come down on it hard enough I still get the knocking noise. I started replacing bearings and noticed the bolt stop(18) but didn't see a bumper stop(19)? Is the bumper stop supposed to be attached to the bolt stop?

    Thanks!
    "Identify your real master."

  24. #24
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    Yes is sits on top of it, when the switch cycles through its full range this bump stopper hits the inside of the switch (preventing your back wheel continuing and hitting your seat post), otherwise the metal of the bolt hits the inside of the switch instead instead (the loud clunk your hearing). If you look at the inside of the switch where the bolt lives you'll see a mark where the bolts been hitting.

    So yes you need a new rubber bolt "condom" as Yeti call it and considering your possibly maxing out the travel a lot (which will be whats killed the bump stopper int he first place? then i'd consider increasing shock pressure to prevent it going full travel too much.

    It's a known issue btw and apparently the new bump stoppers are made from a harder rubber improving life but they are a "consumable" unfortunately. Asking Yeti nicely may see a couple in the post otherwise you'll have to buy some... Andrew over on Yetifan (UK) usually has some in stock.

  25. #25
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    Here's the thread I started about the stop bolt: SB-66: Worn-out stop bolt
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