Carbon Ti Freewheeling problem?

[TobinHatesYou]

I would have stopped riding that bike immediately. In order for your chain to go slack on top, it has to yank the rear derailleur cage. If the freehub binds a little bit more, you might end up ripping your RD right off, especially if you’re in the big ring and one of the larger cogs.

[iamraymond]

Update: I did not attempt to open the hub because I was still waiting for Farsports/Carbon Ti to respond. I was a bit impatient and did a short 20km ride on Saturday to see if the grease just needed some time to set in. After that ride, I already noticed that the hub was freewheeling better. I could backpedal and the chain would not go slack. When freewheeling, the chain would only hit the frame if I was in the smallest cogs/small chainring (i.e. when the chain tension is the lowest) and only at higher speeds or bumpy surfaces. I felt more comfortable with the wheels to try a longer ride (86km) on Sunday which was OK for the most part.

The product manager from Carbon Ti contacted me by email on Monday and provided some instructions to troubleshoot. Similar to the advice provided by folks in this thread, his advice was to check the preload on the bearings and inspect the internals of hub to make sure everything was correctly in place.

More to come...

[iamraymond]

Here’s what I did:

• Removed the cassette. Unscrewed the grub screw on the axle end and turned the bearing preload clockwise.

• Using two 18mm sockets (avoid wrenches which can mar the paint), I turned the two axle nuts counterclockwise to loosen them, and removed the nut from the drive side.

• Pulled the freehub body off the hub. This was on really tight and I had to use an old rubber glove have enough grip to pull it off.

• Pushed the axle out of the hub. The axle was in pretty tight and required a few hits with an open hand to get out.

• Inspected the hub and confirmed that there were three 0.1mm spacers, and the 4 pawls were opening/closing freely. Note: Carbon Ti said there could be either a) three or four 0.1mm spacers, or b) a single 0.4mm spacer.

• Since I already had the hub open, I removed the pawls + springs and cleaned them out with a rag and some Q-tips. I made sure that there was no grease on the three washers, and sprayed the washers with Shimano chain lubricant oil. I was careful to not let any grease get on the washers

• Greased where the 4 springs are inserted, on the tops of the pawls and on the titanium ring. At first I used DT Swiss Ratchet grease, but did it again with Honey Slick.

• Greased the inside of the two bearings on the hub body, then installed the axle back onto the hub. A bit of persuasion with a smack of my open palm was needed to get the axle back in

• Greased the inside of the two bearings on the freehub body, then installed the freehub back onto the hub.

• Turned the bearing preload completely clockwise (i.e. fully open) until it stopped against the axle nut. I closed the hub tightly using the two 18mm sockets. Then I hit the drive side and non drive side of the axle laterally with my hands and noticed that the axle moved slightly. This step was recommended by Carbon Ti, I wouldn't have known to this otherwise.

• Hit the axle on the drive side one last time and tightened the bearing preload counterclockwise until it stopped finger tight. Then, I turned the bearing preload clockwise by 1/8th of a turn to loosen the preload, and tightened the grub screw. Again this step was recommended by Carbon Ti.

• Reinstalled the cassette. One thing I noticed is that I had to realign my rear calliper because the pads were rubbing on the rotors; a clear sign that the axle had been moved slightly when setting the preload. I think by hitting the axle laterally must have released the excess tension on the bearings.

• Tested the bike on the work stand. I could spin the cranks backwards without the wheel spinning. I spun the cranks forward and stopped them (to simulate freewheeling), the cranks stopped immediately. Also, the Honey Slick greatly diminished the freehub noise.

I need to do more testing but so far so good.

Here's a video of the hubs now.

[jas0nt]

Has the problem reoccured since your fix? Thanks for posting the instructions btw.

[Kurt1980]

Another owner of Carbon Ti hubs on Farsports rims.

I have two situations with which I'm hoping to get some clarity if possible.

1. My freehub and friction.
They've never been as bad as the OPs situation here, but I'm wondering if there's too much friction in my freehub?

From new, if I layed the bike upside down and pedalled backwards, the rear wheel would spin with it. Not at the same speed the pedals are moving, but clearly there's some friction between the freehub and the hub body.

It's not until I really unwind the bearing preload and pull the wheel laterally away from the drive side that I can back-spin the pedals without spinning the wheels. Feels nice, but then there's play. This has always been the case.

Is this on par with other's experiences? Or should I be playing with shims inside? To be clear, I've also disassembled the internals and regreased with slickoleum.

Didn't think too much about this issue until I was working on my MTB and was shocked out how easy it was to back-spin the pedals.

2. Bearing replacement.
In terms of bearing replacement for the rear hub, do people just order the bearings from a local supplier (61803 x 3; 61903 x 1)? Or should I order specifically from Carbon Ti?

Also, is there a specific sized removal/installation tool?

Thanks for any assistance.

Kurt

[Nixster]

1 I assume you have tried the steps outlined above? I’ve built a pair of wheels with these hubs and didn’t know the fifth from last step for example. But I don’t have a problem with my hubs.
2 I believe Carbon Ti use NTN bearings which are one of the best available. So either source from them or Hambini, they’re not that easy to find.

[iamraymond]

Carbon TI posted a couple of videos on Youtube on these hubs:
X-Hub SP Center Lock Hub maintenance https://www.youtube.com/watch?v=I6uwpa6GJvk
X-Hub Hub bearings replacement https://www.youtube.com/watch?v=rUbhAMMx3w0

@Kurt1980, I cannot comment about how the shim(s) inside the freehub affect your issue. Before you reinsert the hub you can loosen the bearing preload completely (clockwise) until it rests at the end of the axle. Then use two 18mm sockets to close the axle nut; don't forget to put copper paste on the nut before installing otherwise it is very difficult to remove in the future. Tap the drive side of the axle with your hand or a rubber mallet then tighten the preload counterclockwise until it's finger tight. Release the tension by a quarter turn clockwise then tighten the grub screw. Finally, hit the axle laterally on both sides with your hand/mallet.

Regarding the bearings, in my experience the original NTN bearings lasted a season before getting a bit rough. I replaced the three 6803 bearings with some DT Swiss ones last spring and they became rough much faster than the original bearings. They became gritty which others have said is normal since they are non contact seal bearings. I rarely ride in the rain with these wheels, but I did an event last summer which ended up in the pouring rain so this may have affected the bearing life.

I ordered some Enduro Bearings LLU (full contact seal) and will try those out later this season. I agree with Nixster that the NTN bearings are quite hard to source. I found a place locally that sells SKF bearings but the 6803 were 25EU each vs the Enduro/DT Swiss bearings which were 10EU each.

[iamraymond]

To remove the bearings, you can use a wooden dowel on the inner race and hammer it out. I've ordered one of these from BearingProTools which is the 'correct' tool.

To install the bearings, I purchased a set of these drifts from Aliexpress

[Nixster]

Well, I see these hubs as premium/ boutique options and I think I paid about £400 for them a few years ago. I would see using something ‘cheap and cheerful’ like Enduro bearings as a false economy but each to their own I guess.
I think I will be using the specific tools when it comes time to replace the bearings to avoid damaging the seats. But then I like buying tools!
Happily mine are still rolling smoothly despite getting wet occasionally, like today for example

[Kurt1980]

Just to update this thread. I installed 2x 0.1mm shims between the freehub body and the recess it sits in a couple of months ago.

Spins much nicer now. If I lift the back of the bike up, the rear wheel no longer spins backwards when pedalling backwards.

Shims were ordered from ebay.co.uk, as there weren't any easily available in Australia.