Ask the experts

[smmokan]

Quick question... can I use Rockshox mounting hardware on a Fox shock? I'm pretty sure I can, but wanted to confirm with our in-house "experts". I've got a new frame coming and have the Fox Float shock, but need 8x30mm mounting hardware. Of course, the Fox version is nowhere to be found in stock but I do have a couple extra sets of RS hardware.

[troth]

I got a new bike and on the first uphill when I started to put power into the pedals it felt like the cranks would slip. It wasn't the chain slipping, every once in a while it felt like the cranks would move but that movement did not go into the back wheel. Initially it felt like the chainring slipping on the cranks but after riding for a bit I started to think it was the cassette or hub. The more I rode the less it seemed to happen(almost like something was tightening up), any idea what might be causing this?

[Huskier]

Going to XT 12-speed from GRX 11. I need a new hub, yes? Will I even be able to squeeze on a 12x drivetrain with my current frame spacing? How do I tell?

[toast2266]

I got a new bike and on the first uphill when I started to put power into the pedals it felt like the cranks would slip. It wasn't the chain slipping, every once in a while it felt like the cranks would move but that movement did not go into the back wheel. Initially it felt like the chainring slipping on the cranks but after riding for a bit I started to think it was the cassette or hub. The more I rode the less it seemed to happen(almost like something was tightening up), any idea what might be causing this?

Is it a cheap bike with a freewheel?

If not, any slipping is generally going to be accompanied by an unpleasant noise.

[toast2266]

Going to XT 12-speed from GRX 11. I need a new hub, yes? Will I even be able to squeeze on a 12x drivetrain with my current frame spacing? How do I tell?

You'll need a microspline freehub. Depending on your hub, you might be able to just replace the freehub.

Frame spacing will be fine. 12 speed uses a narrower chain and the cogs are closer together, so it'll fit.

[troth]

Is it a cheap bike with a freewheel?

If not, any slipping is generally going to be accompanied by an unpleasant noise.

the bike is a stumpjumper evo with sram gx drivetrain and I9 1/1 hub. there wasn't any noise when the slipping happened which is why i keep riding. Back at the house using a wall to balance and really pushing on the pedals i was able to get it to slip a little more in the largest cog.

[summit]

Are the rear axle and cassette tight? Take off your rear wheel and tighten the cassette on the driver, like *grunt* level tight. Put the wheel back on and make sure the rear axle is appropriately tight.

If these loosen, then lateral forces of the drive vs rear tire traction can torque and pull the freehub body laterally along the axle enough out of the hub that the pawls can skip... or explode... or fall out. It presents first as little skips... and then free spinning and a long walk/chainless. You might also notice rubbing of the cassette on the frame.

[toast2266]

the bike is a stumpjumper evo with sram gx drivetrain and I9 1/1 hub. there wasn't any noise when the slipping happened which is why i keep riding. Back at the house using a wall to balance and really pushing on the pedals i was able to get it to slip a little more in the largest cog.

The only thing I can think of in that system that could conceivably slip would be the drive ring inside the hub shell. But usually if that happens it's more of a catastrophic, permanent failure. But... maybe it's slipping a bit? Everything else is bolted or splined, so any slipping would probably happen with a bang or a crunch.

Edit: also what summit said. If something is *very* loose, other things could slip

[troth]

Are the rear axle and cassette tight? Take off your rear wheel and tighten the cassette on the driver, like *grunt* level tight. Put the wheel back on and make sure the rear axle is appropriately tight.

If these loosen, then lateral forces of the drive vs rear tire traction can torque and pull the freehub body laterally along the axle enough out of the hub that the pawls can skip... or explode... or fall out. It presents first as little skips... and then free spinning and a long walk/chainless. You might also notice rubbing of the cassette on the frame.

Thanks, I have a cassette tool coming in the mail, once that arrives I will make sure that cassette is tight. I will double check the axel as well. hopefully that is the fix and nothing was damaged.

[troth]

after talking to the place I got the bike from they think it most likely was that the drive ring in the hub was not threaded in all the way during the hub assembly and it threads in the same direction as the pedaling load and will self tighten. Once its tight it wont move anymore. The reason it was happening in the lowest cogs is because that is where the highest torque on the hub is when climbing in low gears. They said no damage should have occurred by pedaling the drive ring tight since it was only partially loose. seem to make sense?

[toast2266]

after talking to the place I got the bike from they think it most likely was that the drive ring in the hub was not threaded in all the way during the hub assembly and it threads in the same direction as the pedaling load and will self tighten. Once its tight it wont move anymore. The reason it was happening in the lowest cogs is because that is where the highest torque on the hub is when climbing in low gears. They said no damage should have occurred by pedaling the drive ring tight since it was only partially loose. seem to make sense?

Yeah, that seems plausible. If it was that, then the slipping should be done since the drive ring would be tight now.

[Dantheman]

Quick question... can I use Rockshox mounting hardware on a Fox shock? I'm pretty sure I can, but wanted to confirm with our in-house "experts". I've got a new frame coming and have the Fox Float shock, but need 8x30mm mounting hardware. Of course, the Fox version is nowhere to be found in stock but I do have a couple extra sets of RS hardware.

I went through this last year when I got a new frame. RS will work but RS hardware needs a steel DU bushing in the eyelet. Fox hardware does not use steel DU eyelet bushing, so a Fox shock probably won't come with one installed and you'll need to source one and press it in. DVO hardware also will work and is usually the cheaper than RS or Fox, but needs a steel DU bushing like RS. No compatibility issues with RS and DVO.

[sethschmautz]

I've had this happen for a few reasons. The first two times it happened was on a Reynolds hub where the internal ring that was pressed in began to slip. Both times it happened were in high torque situations - steep technical climbing situations - but it happened "slowly" - i.e. over about 10-30 minutes before it was completely useless. Hayes replaced both and I opted to upgrade to i9 hydra the second time in the hopes that it wouldn't happen again.

The last time it happened was on the hydra hub and I was absolutely flabbergasted. I couldn't believe I had torched (pun intended) an i9 hub. On inspection my rear thru axle was loose and the freehub body had moved far enough away from the gear ring that the pawls were no longer in contact. I have no idea how that happened but I'm glad that's all it was.

[dannynoonan]

after talking to the place I got the bike from they think it most likely was that the drive ring in the hub was not threaded in all the way during the hub assembly and it threads in the same direction as the pedaling load and will self tighten. Once its tight it wont move anymore. The reason it was happening in the lowest cogs is because that is where the highest torque on the hub is when climbing in low gears. They said no damage should have occurred by pedaling the drive ring tight since it was only partially loose. seem to make sense?

I had a new dt swiss hub recently that had this exact thing, was a very familiar sensation to a bike with a new freewheel installed, first handful of good hard stomps will tighten the threads. Any hub with a threaded-in drive ring is probably vulnerable to it. Mine went away during the first ride

[Huskier]

Brake whisperers: Have a wandering engagement point on a Shimano XT. I understand this is likely a product of air in the caliper, despite having just done a standard bleed. How do I persuade the air to leave my caliper? Asking it nicely did not work.

[Eluder]

Brake whisperers: Have a wandering engagement point on a Shimano XT. I understand this is likely a product of air in the caliper, despite having just done a standard bleed. How do I persuade the air to leave my caliper? Asking it nicely did not work.

This is a feature of Shimano Brakes. It depends on what you have in your bleed kit but cycling the fluid back and forth then trying to get a slight vacuum at the caliper can help. In the end my first sentence has merit.

[mmmm...pow!]

Rear brake? Stand the bike up on the rear wheel so that it's all uphill from the caliper to the lever, then pump the brake a few times. That should move any air to the caliper. Then just attach the funnel with a bit of fluid to the reservoir, pump the lever until you don't see any bubbles, and done.

[Dee Hubbs]

The hard part is getting air out of the caliper during a bleed. Removing any air in the lever is an easier process.
With bleeds I have come to the conclusion that doing the extra work makes the job easier and more effective in the long run.
I always remove the caliper from the frame to get the most direct and straight line to the lever when bleeding. This adds work of reattaching and realigning the caliper after the bleed, but helps in the long run.
It also uses a bit more fluid, but again worth it in the long run.
This also allows you to manipulate and rotate the angle of the caliper during the bleed. This diagram of a see-through caliper illustrates where the air bubble can get trapped.



I do not like to push fluid from the bottom (Caliper) to the top (lever). This pushes dirty old fluid through the system, and puts dirt and grime in the lever body that has more moving parts and seals. The only tie I do a push from the bottom up is if the brakes are dry and brand new (like when purchasing a replacement caliper and lever separate).
I prefer to do the gravity bleed only.
Park Tools has a decent video, but they push the fluid up first, and then do a gravity bleed. I go straight to the gravity bleed.
Skip to 6:00 mark and begin your process bleed there.



Some points and explanations:

The goal is to get all of the air out of the system - focus on this and NOT on getting oil in. its logical to think that once oil is pushed in it will push air out, but that's not always a guarantee. The bubble won't just float to the top, it will go to the highest point and stay there, make sure there is a direct path for the air to flow all the way to the lever.

The way you prep and introduce the oil can drastically impact how much air "sneaks" in with the oil. This is why I like the top down bleed. Even pouring oil into the bleed funnle causes ai bubbles in the fluid, but the gravity bleed is slow enough to allow those bubbles to rise to the top, and prevent you from introducing them into the system. When you push fluid with a syringe, you suck bubbles into the syringe when collecting oil from he container, and then end up pushing those micro bubbles directly into the system.

The orientation of the caliper on the bike may create more places for air to hide. Also, there will always be places for air to "hide" in a caliper, no matter the orientation, so it's important to move both of these around as you go. Go smooth and slow to move that air bubble to get out of the system.

Make sure you address the problem of the free stroke adjustment screw. On levers with this feature, there's a little hole in the side of the bore that can catch bubbles. After you've got everything else pretty much dialed in, turn the free stroke screw out and give the lever blade a few flicks and tilt it around a little bit, then turn the screw back in and repeat.

A majority of this information comes directly from Shimano Service Reps, and reworded with my own experience.

[El Chupacabra]

Any of you have any experience with knockoff disc rotors? I ordered some from Amazon - one piece 6-bolt, look just like Avid G3, measure at 1.9mm thickness. Any reason not to use these? They are returnable, just thought I'd order a pair and see what they looked like.

[summit]

As long as they are built with the right metal to good tolerances, what could be more mechanically simple than a rotor?

[J. Barron DeJong]

Brake whisperers: Have a wandering engagement point on a Shimano XT. I understand this is likely a product of air in the caliper, despite having just done a standard bleed. How do I persuade the air to leave my caliper? Asking it nicely did not work.

Not sure if my experience is typical, but I have new XTR four piston brakes and didn’t have any issues with wandering bite point until I started doing fall night rides in pretty cool temps; maybe 35-40 degrees. But the wandering still didn’t occur during warmer daytime rides.

If that’s similar to your experience, maybe it’s not a bleed issue?

[evdog]

Any of you have any experience with knockoff disc rotors? I ordered some from Amazon - one piece 6-bolt, look just like Avid G3, measure at 1.9mm thickness. Any reason not to use these? They are returnable, just thought I'd order a pair and see what they looked like.

A friend recommended Corki rotors from Amazon. Put one on the front last month. So far so good. It handled 5k of descent yesterday with no complaints.

[climberevan]

As long as they are built with the right metal to good tolerances, what could be more mechanically simple than a rotor?

Agreed. I have a variety of rotors on various bikes and all of them apart appear to successfully transfer the braking load to the hubs. Maybe the Shimano Ice Tech ones manage heat better, but they also wear out quickly. Use your brakes less, and go faster!

[El Chupacabra]

FWIW, these are the ones I bought, in the 203mm size:
https://www.amazon.com/CYSKY-Stainle...52&sr=8-8&th=1

I have one set of fancy Ice Tech rotors, because I thought they might work better or something -- they are the ones that go out of true the fastest. I've been pleasantly surprised by SRAM's basic Centerline rotors, which seem to work consistently (quietly) and stay true.

[Dee Hubbs]

I have a question, how do you get Stans Sealant stains out of clothes?
Brand new black Carhartts on and I was swapping some tires and the bead snapped in place at 100psi shooting a perfect pasty white Stans jizz stain on the crotch of my new Carhartts.