closetbiker

I just had my first, 5,000 km service on my (still new to me) Nexus 8 hub.

I had it done at Mountain Equipment Co-op (I still had some gift certificates left over from last Christmas) and I think it was the first time they did such a servicing on one.

Whne I picked my bike up from the store yesterday, as I walked the bike out to my car I noticed that the pedals traveled (rotated clockwise along with the rear wheel).

When I got home and took the bike out, I held the rear wheel off the ground, rotated the pedals to spin the back wheel, and then held the crank to see how much freewheeling the wheel would do.

Well, it didn't seem to do too much. It almost seemed as if there was a brake on, there was so much drag. Certainly more drag than when I brought it in.

Is this normal, will the drag decrease with some use, or has MEC adjusted the hub a bit too tight?

Ex Pres 

Are you sure this feeling is not due to the insertion of grease? Have you called the shop to inquire? That's the first step.

FBinNY 

Sounds like the hub was assembled to tight and needs some re-adjustment, but not necessarilly.

While it isn't rare for the pedals to turn when walking a bike, it should be a very low drag type action, and you shouldn't feel any forward force. Normally chain and BB friction exceeds hub/freewheel friction and keep the cranks from turning.

There is the possibility that new grease in the bearings is a bit stiff, especially if it's cold, but again, we're talking about a very light drag. If you feel it's more than that bring it back and have the mechanic review his work.

closetbiker

Having just picked it up late in the afternoon yesterday, and commutting into work on it early this morning (I'm just on a quick break here), I haven't but probably should.

I probably should have gone back and said something when I noticed it as I approached my car.

It's also very cold here, but supposed to warm up in the next day. I also can't get back to the shop for the next 4 days. Maybe I should drop them a line and if it doesn't free up after it warms up, bring it back.

fietsbob

There is more going on in an IG hub, than a freehub, multiple planetary gears for a start.

I have a Rohloff hub, they are lubricated with light oil and full of needle and ball bearings,
the pedals turn slowly when I walk the bike.

You can remove the wheel and feel what the axle bearings trsistance,
feels like,
with your hands, perhaps you have mended a puncture,
and then compare, from memory, the feel.

BCRider

If injecting grease into the hub is a normal part of Nexus servicing then you're likely just feeling the grease drag. It should go away in a few days as riding and shifting moves the excess into the nooks and crannies of the hub. Also as you mention it's been darned cold and rather "Ontario like" around these parts the last week. And cold grease doesn't move quickly for any man or woman... So if you want to compare to see if things are getting better after a couple of rides be sure you do all your testing with the hub at the same temperature. If it was room temp when you tried it the first time then be sure to let the bike warm to room temp fully before you test it after riding.

closetbiker

Here's another question. The chain is worn (no surprise) but it seems to me one of the reasons to change a chain when it wears on a conventional drive train is to facilitate good shifting over the various cogs however, with an internal hub, the chain stays on one cog and the chainring.

How important is it to change the chain? I imagine a worn chain will wear the singular cog, but changing that would be relatively cheap.

skilsaw

I've found that shops do the best service and are most skilled at servicing what they sell. There are exceptions to this.

Does MEC sell a bike with a Nexus 8 hub?

skilsaw

Just answered my own question. MEC's hybrid bike called the "Hold Steady" has an 8 speed internally geared hub. Bet that is what you have. Follow the advice of others here in the forum.

closetbiker

I stopped by MEC in the summer to ask if they serviced these hubs because they sold bikes with them and they said, sure. No problem.

When I called last week to see if I could have my bike serviced in time to use it on my commute this morning, they said they could do it in time, but they've never serviced a Shimano Nexus 8 speed hub before. They've done an Alpine once , but no Shimanos.

Apparently, mine was the first they've done.

fietsbob

Worn chain causes a wear pattern to be imparted in the chainrings and the hub cog.

replace the chain or leave it on and replace all 3 at the same time, later, your call ..

closetbiker

I think I'll wait to replace all 3. Even though MEC said the chain had 100% wear, it's working just fine.

FBinNY 

The guidelines for chain wear and replacement are very different for single speed, or internal hubs than they are for derailleur systems.

First of all the relative cost of a single sprocket, and even a chainring if it comes to that, compared to a chain are much lower than with a cassette. Therefore the logic of replacing chains sooner to protect the cassette no longer holds.

Secondly, since there's no idler cage, and the chain has no slack which allows skipping, you can therefore follow the industrial guideline of running a chain until it reaches 3% stretch. That's a whopping 3-6 times longer than the replacement cycle for derailleur chains.

The money saved by running chains longer finances replacing both the chainring and sprocket when the time finally comes (if ever).

closetbiker

That's what I thought. With the derailleur system, I switched the chain (and cogs) when there was sufficient wear that caused chain skip (or slip) over the cassette/freewheel. I used to change the chains every thousand miles or so, so I didn't have to change the cogs as often, but I found I still had to change the cogs eventually. I didn't save any money by buying chains more frequently.

Now I'm wondering what performance problems I'l run into with the IGH that will necessitate a chain/ sprocket/ chainring change. Will the drivetrain eventually skip?

FBinNY 

Single speed drive cannot skip because there's no slack available for the chain to climb outward on the sprockets. If performance weren't an issue you could run them forever or until the sprocket teeth were worn so thin they snapped. But performance declines measurably as the pitch mis-match gets worse.

Remember wear makes a sprocket smaller, but it increases the pitch of the chain making it wind into a larger circle. That causes a chain to ride at the tips of the sprocket teeth, and if you make it impossible by pulling the wheel back, the mis-match will cause increased friction and wear. You can hear this as the classic chain whirring sound getting louder, and feel it as vibration in the drive. Long before it's a serious mechanical or safety issue, you'll knuckle under and replace the drive train.

closetbiker

Thanks for this. I'm sure I'll eventually replace 'em but I'm not in any rush.

(plus, it's an added bonus single speed chains are so cheap, and I'll only need to replace one cog, not an entire cassette, or go on the hunt for a freewheel)