Shimano rear hub drag...or not

[marciero]

Am getting serious chain slap when I stop pedaling on a Shimano Deore XT hub. I've never experienced anything like this on any other hubs. It only occurs when in the smaller cogs, with the chain having less leverage to stop the freehub. In fact in the workstand the wheel spins quite freely, coming very slowly to a stop. Has been doing this since new, now with several thousand miles. Is this a thing with these hubs? Should I try an adjustment, then perhaps clean the pawls and lube with something thin?

[oldpotatoe]

Am getting serious chain slap when I stop pedaling on a Shimano Deore XT hub. I've never experienced anything like this on any other hubs. It only occurs when in the smaller cogs, with the chain having less leverage to stop the freehub. In fact in the workstand the wheel spins quite freely, coming very slowly to a stop. Has been doing this since new, now with several thousand miles. Is this a thing with these hubs? Should I try an adjustment, then perhaps clean the pawls and lube with something thin?

Can't really get to the pawls(only 2)..sealed FHB but remove FHB, take seal off back and use the thin oil, like Mobil One..Most(all) shimano hubs/FHB come pretty dry from factory.

[Gummee]

That's where the Freehub buddy came from

Wish I had one...

M

[marciero]

Can't really get to the pawls(only 2)..sealed FHB but remove FHB, take seal off back and use the thin oil, like Mobil One..Most(all) shimano hubs/FHB come pretty dry from factory.

Hmm... already thinking about upgrade options-DT, WI, etc.

[Gummee]

Hmm... already thinking about upgrade options-DT, WI, etc.

I'm not so sure that there's upgrading from Shimano hubs. Except for a few things, they're pretty well bulletproof.

M

[ColonelJLloyd]

I'm not so sure that there's upgrading from Shimano hubs. Except for a few things, they're pretty well bulletproof.


Interesting comment in a thread started because of an issue with a Shimano hub.

Who knows which of the many Deore XT hubs the OP is actually using, but it's almost hard to find a good hub alternative that isn't at least 100g lighter so there is that.

[Gummee]

Interesting comment in a thread started because of an issue with a Shimano hub.

Who knows which of the many Deore XT hubs the OP is actually using, but it's almost hard to find a good hub alternative that isn't at least 100g lighter so there is that.

Like I said: except for a few things.

100g in the greater scheme of things is nothing. How long are the bearings going to last? How hard will it be to rebuild? How expensive will the new bearings be? Labor?

I know about Shimano hubs. Had many many of them over the years... Pull em apart, re-grease em occasionally, keep riding.

M

[marciero]

I was puzzled by the fact that the wheel rolled so smoothly in the stand. If there was hub drag, it should be evident there. On a long ride it occurred to me that this is a 36t cassette, much bigger than than anything I've ever used. I use Ultegra road mid cage with Wolf tooth for cog clearance. The much greater rotational inertia of that flywheel, coupled with road deraileur, which I assume if anything has a lighter spring than an mtb, are what is causing that the chain slap. So no excuse for me to upgrade. (Well, more two pawls would be nice). But then, who needs an excuse

[cmbicycles]

That's where the Freehub buddy came from

Wish I had one...

M
There was a guy 3d printing something similar to the freehub buddy a couple years ago when I was looking for the Morningstar tool. The link I was sent is dead but maybe is still out there.

[11.4]

Going to higher tension isn't necessarily helpful, because it would just cause friction. You may be getting on the right track. With a huge platter like a 36, you have to carry a fair bit of chain and have quite a bit of slack in the higher gears. As a result, the chain is prone to slapping anyway when anywhere but the huge sprockets (and when on those, you have it lifted so far from the chain stay that no slap will happen anyway). When you add 20+ links to the slack and you also lower the chain to much closer to the chain stay, it's more prone to slap anyway. If you're getting slap when in the big sprockets, there's something else really wrong, but I'm guessing you only get it when you're riding in bigger gears. At that point the chain is close to the chain stay and there's a lot of extra chain to manage. You might try a rear derailleur with a long cage. You might also see if you're carrying extra chain -- see if you can take off a few links and it'll improve things.

[marciero]

Yes, chain being closer to stays is another thing. Only getting it in the big gears. So actually three things going on in the small cogs, the other two being less tension in derailleur, and that the "pulling" force of the chain acts through a smaller moment arm/lever (the cog radius). The latter two result in less torque slowing the rotation of the cassette. I could definitely remove a link or two as I was conservative regarding chain length. On the other hand it doesn't really bother me, especially knowing that it is not some inefficiency.