Gummy Bear

I recently bought a Novara Fusion primarily as a recreational/grocery getter bike. It pretty much does everything I had hoped it would. However I have some basic mechanical question which I could not find the answer to thru searching here, Sheldon's, Park's or my book. So here goes:

1. I love the Nexus-8 hub but it is noisy in 3rd gear and only that gear. I checked for obstructions that could be hitting the chain in 3rd but found nothing. I checked the cassette joint adjustments and the yellow setting lines line up. I cleaned the chain, chain ring and cog and still it persists. The noise isn't bad but it strange that it is only in that gear.

2. The Roller brakes work but is the brake drum suppose to be so loose? It tightens up when I pull the brake lever but otherwise it has a lot of lateral play in the brake drum (alum. slotted disk). I could not find any info. on this as all documentation lists brake unit as a whole and not its component parts. Since there are no serviceable parts (other than to add grease when problematic syptoms arise), does one just replace the whole roller brake unit when it is worn out?

3. The bike comes with a 46T chain ring and a 19T cog which gives me a range of 108 to 35 gear inches. Since I find myself hardly ever using 7th - 8th gear and I live in a fairly hilly town, would it make sense to go with a 22T or 23T cog. This would yield an approx. range of 90 - 30 which would seem to be a better fit to my daily riding. If I change the rear cog, do I also have to buy a new chain to add length or can I just buy additional links? Also where can I find a Nexus cogs? The only place I have found one is at Bikeman. Are there any other online retailers who sell them?

4. I got a Finish Line chain cleaning tool but it doesn't seem to work with my setup. As near as I can tell since there is only one chain ring and one cog, there is no play in the chain for the tool clamp on to. Am I doing something wrong or must I take off the chain every time I want to clean it?

5. Where can I buy a chain guard (hockey style or full) cause the chain "protector" don't protect my pant leg .

Sheldon Brown

I love these hubs, but I'm not a big fan of the Rollerbrakes. I don't care for a brake that weighs a pound and a quarter and isn't all that powerful. They're also prone to fade if used in really steep conditions.

I left them off of my own Nexus bikes (I've got three of 'em, 1 7-speed and 2 8-speed.) The looseness is normal, I'm pretty sure.

We stock the sprockets, up to 24 teeth. See https://harriscyclery.com/sturmey (these use the same type sprockets as Sturmey-Archer and SRAM internal gear hubs.)

For each tooth you add, you'll need to move the chain forward by 1/8". If you run out of chain, you'll probably need to buy a new one.

Those chain cleaners only work on derailer bikes. When you don't have a derailer, chain cleaning is much less important. See: https://sheldonbrown.com/chains for recommended chain cleaning technique.

Sheldon "Neck's Us" Brown

phidauex

EDIT: Damn, sheldon beat me! He must have some sort of 'nexus' detector....

1. I'm not sure about the noise, but I doubt it is a mechanical problem. Nexus hubs tend to be louder than derailleur systems, but that isn't usually a problem. 4th gear is direct drive on your hub (I think.. Its either 4th or 5th.. but I think 4th), so it should be the quietest, and the things adjacent to it will tend to be louder since they are usually on other planetary rings and would be an agressive ratio on a different ring. On my three speeds first and third and loud, and second is dead quiet (and smooth as butter, since its directly driven).

2. I don't know if the drum is user replacable or not, but you should be able to find the parts for your model on this service manual from mr. brown (you may have missed it the first time through, his website is rather labyrinthine). https://www.sheldonbrown.com/nexus8/index.htm

3. They use a special cog, but the part numbers for the cogs are on the parts lists on the sheldon link. I think they go from 16t to 22t. You should be able to order them from any shimano dealer, though they probably don't have them in stock. You might check with Harris Cyclery though (sheldon's shop), since they have a special love for internal hubs and might stock the parts you need.

4. You may have to drop the chain each time. Alternatively, you can pop off the rear wheel (assuming you have horizontal dropouts), remove the chain from the rear wheel, and use the crank to rotate the chain through a coffee can of mineral spirits. Then let it dry, reassemble, and relube on the bike. I've never really used a chain cleaner tool.

5. I don't know where to get good chain guards... sorry!

peace,
sam

dbg

I loosen the rear hub way forward and then can barely use the chain cleaner. It works but it's a little awkward.

Also, all three of the brakes I have (I use none of them) seem a little loose, but they clearly tighten up when you pull the cable.

Also my commuter clicks a little in 5th (nexus 7) but has never failed a shift, ever. And I have a short steep hill that I "stand" on every day. I'm loving these hubs (have 5 including all my kid's bikes). Plans to put one in the old schwinn twinn i just restored.

Gummy Bear

Thanks for all the replies guys. Nice to know what experiences you have had with these parts.

I am not really all the concerned about the braking power of the roller brakes in the rear. I just wanted to make sure it is installed correctly. I figured they are my "Houston we got a problem" brakes. All I need them to do is to slow me down enough to say a couple prayers to my heathen gods before I crash.

Interesting ... I am not the only one with a noisy Xth gear. I have read others reporting the noise diminishing with time. Yet another who claim to have gotten a warranty replacement because when he contacted Shimano, they say it is not normal for one gear to be louder than the rest. Who knows the real "truth" of the matter but like dbg said, it hasn't failed a shift yet. I wonder if the "premium" version got rid of this noise? Actually I kind of feel bad since my wife's Nexus-3 is much noiser than my 8 so I guess I am a little spoiled.

The chain thing is just a nuisance. I'll probably either buy a powerlink or a SRAM chain for easy maintenance.


This is the one part I did not understand. I am still learning the jargon, so what does one mean by "moving the chain forward". Sorry but searching for common words is akin to googling your friend Dick.

phidauex

I think he means you have to move the wheel forward by 1/8", because your chain is staying the same length, but it has to pass over a larger cog. Look at how your rear wheel mounts, and see how far forward you could theoretically adjust it, for every 1/8", you can add a tooth. If you want more teeth than that, you'd need a new (longer) chain.

peace,
sam

Sheldon Brown

Nope there's nothing "special" about these spockets, they're the same as used by virtually all internal gear hubs from Shimano, Sturmey-Archer and Sram.

They exist from 13 to 24 teeth, and we stock them all, but due to the nature of the Nexus shift linkage you really can't go any smaller than 16.

See: https://harriscyclery.com/sturmey

Sheldon "3-Spline" Brown

phidauex

Ahh, I was under the impression that the cogs were different than my old SAs! I suppose its good news that they aren't. What would we do without you, "3 spline" Brown? Probably just wallow around in our own filth wondering why our bikes are just big piles of rusted metal in the corner.

peace,
sam

Gummy Bear

Thanks for phidauex. Since Sheldon "fill in the blank" Brown didn't comment on your explanation I am assuming that is indeed what he meant. Now I am probably over thinking this but is the 1/8" forward in relation to the axis of the dropout or the horizontal plane (the ground). Wouldn't it be easier to just add or subtract links as necessary and use the depth the rear axle sits in the dropout for fine tuning the tension?

Sheldon Brown

That is what I meant, should have said "For each tooth you add, you'll need to move the axle forward by 1/8".

You are overthinking this.

It has to move 1/8" in the direction of the chainring. On bikes with well designed dropouts, slanted down toward the front, you will move it slightly more than that along the slope of the dropout. But if we're really being fussy, going to a bigger rear sprocket makes the straight runs of chain slighlty closer to parallel, so it's actually a skosh less than 1/8".

Subtracting links is easy enough, but you were talking about going to a bigger sprocket, which means adding links, which you may or may not have available.

Note also that adding/subtracting links is a much coarser adjustment. For each chain link you add/subtract, you must move the axle 1/2", 4 times as much as for adding/subtracting a sprocket tooth.

If you install a half-link (a.k.a. "offset link) that only moves the ale 1/4".

Sheldon "Round Numbers" Brown