Bicycle Mechanics - Nexus 8 internal hub feels rough pedaling in low gears

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photogeek
08-27-11, 04:54 PM
I picked up a (mostly) new public D8 last weekend from their warehouse sale. It has an 8 speed shimano nexus and horizontal dropouts, and appeared to be in great condition except for a few dents in the fenders. Public didn't have details but said most of the warehouse bikes were hardly used and just couldn't be sold as new, whatever that means.

When pedaling in gears 4 and lower, it feels rough - like something is grinding or not quite meshing properly. The roughness comes through the pedals. When I powered up a short 10% grade in gear 2 the other day, it was especially bad. Gears 5 and higher feel just fine. We have another (brand new) bike with also with a nexus 8 hub, where all 8 gears are nice and smooth, so I am pretty sure there is actually something going on with my bike.

What sort of problems could cause this, and how would I go about fixing it?


MichaelW
08-28-11, 03:27 AM
The only adjustment you can do is to use the cable tension adjuster to ensure that, in 4th gear, the yellow index markers match up.
If that dosnt solve the matter then you may want to take a peek inside and maybe give an oil dip. Its not as difficult as it sounds and if you can handle cup and cones, it will be OK.
The internals come out as one unit. Some people break them open for further cleaning up but I havent.

tcs
08-28-11, 06:55 AM
On the Nexus/Alfine 8, gears 1-4 use the super-low compounding planetary. You might try oiling (http://bike.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50lparsys-0014-downloadFile.html/07)%20Maintenance%20Oil.pdf) it.


LarDasse74
08-28-11, 09:00 AM
My Alfine 8(very similar internals to Nexus 8) is x-tra smooth in all gears except for #1, which has a slight roughness to it. As above, make sure the two dots on the cassette joint line up perfectly when in 4th gear.

Other wise take it back to the shop/warehouse or whatever and have them look at it. It should be smooth as a baby's ass.