Why you should not forget about this 50h lower leg service- Mtbr.com
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  1. #1
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    Why you should not forget about this 50h lower leg service

    I got this Rockshox Pike from "The Pros Closet" for $200. The outside looked beat up but the stanchion were fine, I thought it was a great deal... I took it apart yesterday for a travel upgrade and service and had to find out that it is quite bad on the inside. The Oil was thick and dark, and the stanchion are worn off at the inner shock bearings, in 2 spots all the way through.

    The bright spots in the pictures are not reflections but the worn off coating, the stripes come from the channels in the bearings.

    I'll just ride it till it starts to stick now, but I certainly will service my new Forks much more often after seeing this!

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  2. #2
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    I suspect that fork had a heck! of a lot of hours on it. Bath oil is normally fairly thick, but not dark.

    I like to hang my bikes from the front wheel so bath oil can trickle down and keep the foam rings saturated and bushings lubed. Letting them sit inverted for a while can do the same.
    Do the math.

  3. #3
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    Yes I think so, too. I'm always a bit hesitant to store the bike hanging or even upside down, someone told me that air from the reservoir at the lever can flow to the caliper- not sure if this is an old mountain bikers wives' tale, though.

  4. #4
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    Quote Originally Posted by Chris_PA View Post
    Yes I think so, too. I'm always a bit hesitant to store the bike hanging or even upside down, someone told me that air from the reservoir at the lever can flow to the caliper- not sure if this is an old mountain bikers wives' tale, though.
    If you have a crappy bleed on your brakes, yes that will happen. However I think dropper posts don't like to be stored upside down. At least my bikeyoke explicitly mentions not storing it upside down due to getting air mixing with the oil.
    https://youtube.com/c/jamesstoup - Check out my racing on Youtube

  5. #5
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    I hang all my bikes, never had an issue with a dropper or brakes. Hanging only makes existing issues come to the surface, it doesn't create them.

    Also, your fork looks like it has a bushing alignment issue. Service is very important, but if it was a service issue the ano would be worn off all the way around, not in one spot. It also would not have groves from the slotted bushings. If you buy a new CSU, you will likely have the exact same issue in another 30 hours or so.

  6. #6
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    Quote Originally Posted by mullen119 View Post
    I hang all my bikes, never had an issue with a dropper or brakes. Hanging only makes existing issues come to the surface, it doesn't create them.
    That's a great way to put it.

    Quote Originally Posted by mullen119 View Post
    Also, your fork looks like it has a bushing alignment issue. Service is very important, but if it was a service issue the ano would be worn off all the way around, not in one spot...
    Possibly, but by far the main forces on the bushing and stanchions is front to back under compression and braking so I would expect to see wear on the front and back of a stanchion and not the sides.
    Do the math.

  7. #7
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    Quote Originally Posted by Lone Rager View Post
    That's a great way to put it.



    Possibly, but by far the main forces on the bushing and stanchions is front to back under compression and braking so I would expect to see wear on the front and back of a stanchion and not the sides.
    There is more side loading in a fork than you would think, it doesn't take much turning force to create enough side load to show wear. The fronts and backs would get it worse, but the sides would still show signs of wear if it was an oil issue.

  8. #8
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    Quote Originally Posted by mullen119 View Post
    Also, your fork looks like it has a bushing alignment issue. Service is very important, but if it was a service issue the ano would be worn off all the way around, not in one spot. It also would not have groves from the slotted bushings. If you buy a new CSU, you will likely have the exact same issue in another 30 hours or so.
    Also don't think it's an alignment issue, the wear is quite even on the front of the fork. Since the fork is on an angle this is the area where the bushing edge presses on the fork most and the friction is the highest. I can't figure a way how the fork or bushings could be twisted to cause even wear on both sides otherwise.

    I checked for CSU (crown stanchion upper) prices and for the old A1/2 forks its around $350, much more than for the newer B1. That's not worth it, I'll just ride it maybe at some point someone will put it one on sale.

  9. #9
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    Quote Originally Posted by Chris_PA View Post
    Also don't think it's an alignment issue, the wear is quite even on the front of the fork. Since the fork is on an angle this is the area where the bushing edge presses on the fork most and the friction is the highest. I can't figure a way how the fork or bushings could be twisted to cause even wear on both sides otherwise.

    I checked for CSU (crown stanchion upper) prices and for the old A1/2 forks its around $350, much more than for the newer B1. That's not worth it, I'll just ride it maybe at some point someone will put it one on sale.
    Most bushing tolerance spec is .06 to .075mm . That's total tolerance, leaving .03 to .0375 of a gap in between the bushing and stanchion for lube. I think you are underestimating how much force a fork sees in use, and how tight the tolerances are.

    I have had multiple pikes (first gen 2014-15) come through that had similar marks. Replaced the CSU on one and had the same wear pattern return after 6 hours of use.

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