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Got a quick question on a wee DT Swiss 350 hub issue. The cassette is slipping in the highest (i.e. hardest) gear when I'm properly stamping on the pedals.
This says to me that my star ratchets are worn and need replacement. However, the hub is relatively new and hasn't had a lot of miles done it (on my big day out bike rather than my regular work horse).
Mixed into that is the current price and availability of replacement ratchets at North of £50 and difficult to get hold of in 18 tooth flavour.
Before I take the plunge, any other thoughts on what the slippage might be down to or whether to go for more teeth (was told many years ago by TF tuned who were the service folk for DT Swiss at the time that 18 tooth was the only one suitable for MTBs)?
36T ratchet is fine for mtb's
Ive run a 36T ratchet on my e-mtb with no issues
Id be very surprised if the star ratchets have worn that much with little use
Are you sure the hardest/highest cassette cog hasnt worn and its your chain slipping?
Have you removed the free hub and checked the star ratchets for wear etc?
It is definitely the cassette slipping unfortunately. I have taken the hub apart and cleaned plus regreased my ratchets using the tiny tub of special DT Swiss grease I bought years ago. My experience is that it is sometimes pretty hard to see wear on these things although that could be my rubbish eyesight.
The lack of use is what puzzles me. The only time I've ever had this before was in the depths of winter with a 5 year old hub. That level of reliability is one of the main reasons I use DT Swiss hubs on my bikes.
I've only had slippage once, as a result of a loose rear axle. It allowed the cassette/freehub body to move away from the hub body under load and chewed off the corner of some teeth. This was 36t. Resulting damage although hard to see was terminal.
I have also seen the same thing happen when "carelessly" tightening a cassette onto a freehub without a chainwhip or much attention and with it not being not being fixed together axially and relying on the start ratchet to provide the stop, the cassette jumped on the teeth. No damage, but a good reminder nonetheless.
Extra care was required for oneup minidrivers as those just let the cassette/driver fall off the axle when not in the bike.
I'd pull off the cassette with the freehub and have a look at the internals, never had slippage due to the hubs, always worn cassettes, my current DT hub has seen about 3k on an ebike, and not had a happy life, but still runs well, to mangle those ratchets you'd have to go some, unless it's not on correctly, so on partially engaging?
As above though, the whole thing comes off with a little leveraging either side, check it, make sure the springs are the right way round, the spacer is in correctly and the ratchets look in good order.
If you need an 18t DT ratchet i think i have some spare, had so many DT wheels over the years i think i've got about 3 spare sets!
I run a 36 ratchet with no issues, I must have the 18 spare somewhere.
Ooooo. Spares! If I was you, I'd sell them to desperate idiots like me. Cheapest out there is £40 odd from bike24. There's money in them there spares.
I'm going to give the whole thing another clean and grease to hopefully stop the issue.
The trouble with the star ratchet system (great though it usually is) is that any tooth damage —> slippage —> more damage. If there is a machining burr or anything else (eg grit contamination during assembly) meaning the teeth don’t mesh properly, they can destroy themselves quite quickly.
I had one that died on the first ride. The warranty replacement is absolutely fine 7 years later. I bet there’s a bathtub failure curve.
That said, if it exclusively happens in one gear, it could be something chain/cassette related.
Sounds more like a worn cassette/chain issue. Smallest sprockets wear faster than large ones.
If it was star ratchet issues, it would be more likely to skip in 1st gear - more leverage/torque.
I've got a new pair of 18t if anyone wants to buy them. Well used once.
Are you sure it is not the chain. A stiff link can stop the chain from properly wrapping around the smallest cog causing a slipping effect.
I’ve had this exact same issue for the last month or two (freewheel slipping but only when pushing in the higher gears). I finally stripped it all down, cleaned everything and put it back together with a light dab or two of slick honey. It seems to be working properly again.
I may have been lucky, this time, to get away without needing to swap the star ratchet parts. In case things change I’ve ordered up some ZTTO parts from AliExpress for a fraction of what the official ones would cost if anyone had them in stock.
https://a.aliexpress.com/_mt2IujU
i'd avoid those ZTTO ratchets like covid, mine failed on the first ride leaving me stranded miles from home. i have some spare ratchets knocking around if no one else helps you out.
Just a quick update in case anyone ever comes back to this. The ZTTO star ratchet arrived today and isn't even close to the quality of the DT Swiss parts that came out of my hub. I will likely give it a try at some point just to see if it works (nowhere to far from home mind) but won't be expecting too much from it.
chinertown forumers seem to think it's OK. not pretty, but wears OK.
http://chinertown.com/index.php/topic,3078.msg35539.html#msg35539
I went for new 18t ones from bike24. Cheaper at about £40 including new springs and a new tub of special DT Swiss grease. Not arrived yet though, so sticking with cleaning and regressing for the moment. Just going easy on the cranks in the meantime.
Could it be this?
https://road.cc/content/tech-news/dt-swiss-acknowledges-issues-ratchet-exp-hubs-283351
If so it sounds like a warranty claim
It won't be that, that only affected a small batch of the early EXP hubs, the 350 doesn't use EXP.
Smallest sprocket doesn't usually take the biggest torque (or power or, err, something engineery). I'd doubt it's the freehub slipping if you can only replicate in that gear.
Maybe the cassette's not seated quite right (maybe even a rogue spacer behind it) and that's stopping the outer sprocket from seating on the splines and allowing it to slip? (clearly bollocks if this is a one-piece cassette, mind)
It's a microsoline cassette, so the final sprocket actually seats on the next to last sprocket rather than the freehold (rubbish design if you ask me). No evidence of any slipping damage on either the freehold or the two final sprockets, so I just can't see how they'd have slipped (I'd expect to see some damage). The cassette lock ring is horsed down tight and the two spacers are in the right order. Must admit, I'm not the biggest fan of the microspline freehold and cassette design, let alone the temperamental rear derailleur but it does seem to be fairly solid on both bikes compared to friend's SRAM setups.
Too much btension resulting in too little chain/sprocket overlap on the 10t?
You might have to get a new body. Check the coating inside the body where the ratchet glides. Look for premature wear. Black grease after 10 hours use or less is a warning sign, it's supposed to be as new (red).
I guess some dt 350 hubs have a similar problem as the exp hubs. Premature wear of the coating inside the body. The ratchet in the body doesn't move as it supposed and both ratchets will suffer premature wear or get stuck and fail as a result.
I had this problem with two XD-bodies. Two sets of ratchets destroyed or with premature wear. DT 350 hub with 18T, 3 months old.