Ask the experts

[toast2266]

I really don't agree with the "rub dot fluid on the pistons" thing. It's outside the sealed system, on the wrong side of the seals. About all I can see it doing is stripping the paint off the inside of the caliper and maybe your frame and possibly contaminating the pads and rotor.

Sram's caliper rebuild instructions specifically say to rub dot fluid on the pistons. (skip to 3:30)

[toast2266]

Question from my buddy who is racing with me next weekend:

You think a new take off EXT Storia from a Nukeproof Giga would work on a Spire?

Are EXT shocks all shim tuned per frame or do they just fiddle with the knobs at the factory and in reality they are all the same shock?

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I'd be kinda surprised if the shim stack was the same in a Giga and Spire. Leverage curve on a Giga is more progressive than a Spire.

That said, I bet it'd work. It might not be 100% optimal, but I doubt the tunes for each bike are dramatically different.

[jamal]

Well sure when fully overhauling the caliper you want some on the pistons and seals so it's not going together dry.

When it's already together and the pistons are in there they tell you specifically not to do that

https://youtu.be/xTGHdFt5Y-s?t=150

[toast2266]

Well sure when fully overhauling the caliper you want some on the pistons and seals so it's not going together dry.

When it's already together and the pistons are in there they tell you specifically not to do that

https://youtu.be/xTGHdFt5Y-s?t=150

Well that's just talking about replacing the pads. We're talking about re-lubing the pistons when they get all gummed up. The *best* way to do that would be to do a full caliper rebuild (which involves lubing the pistons). But to short cut that process, it makes sense to get the pistons out as far as you can, clean them up, and put a little lube on them. Here's Park Tool telling you to do exactly what we're talking about (at ~3:30).

[Roxtar]

I've also heard recommendations to put a little DOT fluid on the outside as a lube and I don't get the reasoning behind it.
Lab setting? Sure.
Outside?
Very quickly that "lube" will be turned into a gritty slurry. Now your seals are trying to push that away.
It just screams "Bad Idea" to me.

[D(C)]

Well that's just talking about replacing the pads. We're talking about re-lubing the pistons when they get all gummed up. The *best* way to do that would be to do a full caliper rebuild (which involves lubing the pistons). But to short cut that process, it makes sense to get the pistons out as far as you can, clean them up, and put a little lube on them. Here's Park Tool telling you to do exactly what we're talking about (at ~3:30).

One great trick is using an allen key as a piston block to prevent them from extending too far. See ~6:15 in this video: https://youtu.be/ys9bUOJ0qg0?t=377

[nortonwhis]

Question about fork bottom out.
I don't think i can remember bottoming out my fork in the past year, but rode one of the gnarly trails we have around here the other day and bottomed out my fork at least 10 times, metal on metal clanking kind of bottoming out. Nearly got yeeted out the front a bunch of times out of that as well. Cranked the HSC and LSC all the way up and no change (not that it likely would). Checked my fork pressure, its at 78 PSI for a 2022 Fox 36 which is still the weight group above me.
Please select an answer from the poll
a) Using shitty technique on gnarly slab transitions?
b) Fork needs a service
c) riding like a pussy all the other times
d) need another token of 10 PSI next time I go back there
e) other - please explain

Thanks in advance.

[Jtlange]

Question about fork bottom out.
I don't think i can remember bottoming out my fork in the past year, but rode one of the gnarly trails we have around here the other day and bottomed out my fork at least 10 times, metal on metal clanking kind of bottoming out. Nearly got yeeted out the front a bunch of times out of that as well. Cranked the HSC and LSC all the way up and no change (not that it likely would). Checked my fork pressure, its at 78 PSI for a 2022 Fox 36 which is still the weight group above me.
Please select an answer from the poll
a) Using shitty technique on gnarly slab transitions?
b) Fork needs a service
c) riding like a pussy all the other times
d) need another token of 10 PSI next time I go back there
e) other - please explain

Thanks in advance.

If you like how it rides except for the bottom out, add a token. If you feel like it needs more mid stroke support (diving on you), add air.

[skinipenem]

Question about fork bottom out.
I don't think i can remember bottoming out my fork in the past year, but rode one of the gnarly trails we have around here the other day and bottomed out my fork at least 10 times, metal on metal clanking kind of bottoming out. Nearly got yeeted out the front a bunch of times out of that as well. Cranked the HSC and LSC all the way up and no change (not that it likely would). Checked my fork pressure, its at 78 PSI for a 2022 Fox 36 which is still the weight group above me.
Please select an answer from the poll
a) Using shitty technique on gnarly slab transitions?
b) Fork needs a service
c) riding like a pussy all the other times
d) need another token of 10 PSI next time I go back there
e) other - please explain

Thanks in advance.

Couple thoughts...

Try increasing your air first. Then tokens.
Check Rebound dampening. Too slow Rebound and you'll pack down and bottom out.



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[J. Barron DeJong]

Check Rebound dampening. Too slow Rebound and you'll pack down and bottom out.

^ If it’s only bottoming out through a series of hits. If a single hit will do it, probably nothing to do with rebound.

[skinipenem]

^ If it’s only bottoming out through a series of hits. If a single hit will do it, probably nothing to do with rebound.

Yes "packing down" = bottoming out with a series of hits. I should have been more specific. I'm guessing he might not be able to discern the difference, though, and it might be easier to just try it.

@nortonwhis could try this method:

Fwiw set Rebound as fast as possible without the wheel coming off the ground when you push the fork with your hands as deep into the stroke as possible at a standstill (not standing or sitting in the bike) and let go. Then ride it. Then add Rebound dampening as needed to settle down any chatter / harshness/ bounciness / frenetic sensation / lack of traction turning. This is a quick way to get close and should eliminate rebound as a factor in bottom out. There are more nuances to Rebound settings, but will leave those out for sake of staying on topic.

I'm no pro though so take it with a grain of salt

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[Canada1]

I clean my pistons with a combination of rubbing alcohol and compressed air. I have yet to find a good solution for something that seems to be a recurring issue, but this is the best I've found.

[joetron]

I generally clean the pistons with Iso on a q-tip, then dab a bit of DOT or Mineral oil on the piston with a q-tip and push them back in and cycle the lever a few times to make sure they’re moving normally. Then push them back in and spritz the caliper with iso and floss a shop towel through to remove any excess fluid outside the piston and seal.

[toast2266]

^^^ that's my process too. I also blast them with air after cleaning with the q-tip.

[SchralphMacchio]

Norton specifically mentioned gnarly slab transitions, which would be less likely to be a rebound issue than a worst case big hit issue that isn’t manifesting in other types of trails. He also mentioned that cranking compression settings to fully closed didn’t seem to change much. Then there is the metal on metal sound bit.
Sounds to me like the first step is a service and tear down then second step is to debug air pressure, air volume, and compression settings?
Disclaimer, #notanexpert

[nortonwhis]

Went up to 82 PSI on a more normal trail around here but still had well over an inch left even after a few big impacts. Def felt a little aggressive. I'm going to try going down to 80 PSI, and then maybe a token if that doesnt work and drop a PSI.

Edit: Yeah def not a rebound issue. Fork feels great except on that one trail.

[grskier]

Went up to 82 PSI on a more normal trail around here but still had well over an inch left even after a few big impacts. Def felt a little aggressive. I'm going to try going down to 80 PSI, and then maybe a token if that doesnt work and drop a PSI.

Edit: Yeah def not a rebound issue. Fork feels great except on that one trail.

That's a decent jump in psi.
If that fork is set up and feeling good 90% of the time, it may just be the adjustment for that ride... I'd hate to see someone get away from something that works most of the rest of the time. That said this sounds like an order of magnitude more impact than what you're usually riding... Is that the case?

[SchralphMacchio]

I'm not clydsey or manly enough to have had super nasty fork bottom out (I mean I bottom mine on almost every ride, but that's not obvious until I'm at the bottom and I can see where the O ring is at), but shouldn't a 36 bottom out bumper not sound like metal on metal clanking?

[toast2266]

I'm not clydsey or manly enough to have had super nasty fork bottom out (I mean I bottom mine on almost every ride, but that's not obvious until I'm at the bottom and I can see where the O ring is at), but shouldn't a 36 bottom out bumper not sound like metal on metal clanking?

I've yet to find a fork that can't produce a metal on metal clank. Bottom out bumpers can only do so much.

And rough transitions off of steep slabs are really good for that sort of thing. Your weight is forward, you're pushing your front end through the transition, and there's pretty frequently a hole there from people skidding off the end of the rock. All of that is a recipe for a nice clank.

If the fork feels good elsewhere and you're not frequently using full travel in other situations, I wouldn't sweat it too much. Maybe just don't push through the transition at the bottom of the slab quite as hard, and go on the edge of the riding line where the hole isn't as big.

[Johnny Utah]

Is it toast? Miraculously been rolling for a couple hundred miles like this and still holding air. But I need new rubber soon and expect I’ll have to face reality of the bead not seating. Fixable? I’m eyeing some new WAO hoops…




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[skaredshtles]

<snip> Fixable?

Maybe.

I’m eyeing some new WAO hoops…

Do this. You know you want to. And you can even "fix" this one and use it as a backup wheel.

[gramboh]

Is it toast? Miraculously been rolling for a couple hundred miles like this and still holding air. But I need new rubber soon and expect I’ll have to face reality of the bead not seating. Fixable? I’m eyeing some new WAO hoops…

Had a similar dent in my rear DT Swiss EX1700 (EX511 rim I believe). Could not get tires to seat tubeless after that so I ran a tube for about 6 weeks. Was able to kind of work the dent out with pliers but could never get spoke tension consistent and ended up with other hops in the rim. Went with WeAreOne Unions (on I9 1/1) for $1399CAD. Very happy with them, 32h front/rear, no more fears of smashing rocks (other than cutting tires haha).

[Dee Hubbs]

Had a similar dent in my rear DT Swiss EX1700 (EX511 rim I believe).

You are correct. The 1700 is a wheel system rim with a different decal, it’s identical to the rim only 511.

[Tailwind]

I just bought some we are ones today.. replacing M1900’s.

So you’re telling me I’m likely okay if I ping the rims a few times per month from a rim damage perspective.

Had a similar dent in my rear DT Swiss EX1700 (EX511 rim I believe). Could not get tires to seat tubeless after that so I ran a tube for about 6 weeks. Was able to kind of work the dent out with pliers but could never get spoke tension consistent and ended up with other hops in the rim. Went with WeAreOne Unions (on I9 1/1) for $1399CAD. Very happy with them, 32h front/rear, no more fears of smashing rocks (other than cutting tires haha).

[simple]

Dtswiss rims are meant to bend and bend back. Been like that for decades now. There is a reason they are the racers favorite