ixcuix

I have a Jamis I think around 2002 Commuter 3.0. It has a Jamis 8G-8R22 Shimano 8 speed internal hub. After changing the gear shift cable and replacing the part that the cable end fits into, the gear shift does not seem to go down to gear # 1.
One strange thing is that now with only 7 gears the hub seems to be working better with no noise as before all this happened.
There are a few things I am wondering about.
A. Is there any other measurement used besides 101mm for the end cable distance?
B. Is the chain length critical?

Dan Burkhart 

There are a couple of cassette joint models, the most common requires the anchor to be set at 101 mm. I have not encountered any that do not, but apparently they exist.
Also, ensure the cable is correctly routed over the cassette joint capstan, and that the two alignment marks line up with the shifter in 4th gear position.

Geekage

Did you adjust the cable tension so that the yellow lines line up in 4th gear? If not, find out how to do the adjustment. Otherwise it sounds like the end cable distance isn't quite right if you're missing the loosest (1st) gear.

ixcuix

Thanks. The cassette joint is CJ-8S20. I will see if the cable is routed correctly and the 2 marks line up in 4th gear. What about the chain? If it is worn out would it cause this problem? One thing that leads me to believe that the chain is not correct is the 2 adjusters (not sure the technical term) that adjust the position of the axle (how far forward or backward) could not possibly reach the axle in the position where the chain is tight. Therefore, I am thinking the chain could be supposed to be a bit shorter. Wouldn't this change the tension on the gear shift cable?

dsbrantjr

The chain should never be tight, you should be able to move the top and bottom runs of chain up and down perhaps 6mm in the tightest position.

sweeks

Shift cable tension is independent of chain tension.
The Nexus 8-speed hub is a "low-normal" hub; when the cable is completely slack, the hub will be in the lowest gear. Check that the cable is slack, or nearly so, when the shifter is in Gear 1. If there is tension, it may not be able to get into low gear.

ixcuix

I found this. A WHOLE LINK IS LIKE MOVING THE AXLE 1/2 IN.
A HALF LINK IS LIKE MOVING THE AXLE 1/4 IN.

What I am wondering is if the axle is moved. (I have horizontal drop outs), will this change the cable tension?
I am not sure if I explained this correctly, but when my back tire is tightened down with the chair in a semi tensioned state the horizsontal drop out axle adjusters CAN NOT REACH THE AXLE. This leads me to believe the chain is too long.

Thomas

ixcuix

Sweeks

I did not see your post before I wrote the above reply . Thanks. I am almost positive there is plenty of slack when the gear shifter is set at 1. Maybe I am getting into 1st gear, AND NOT getting into 8th gear. I just shifted to 1st gear, and there seems to be enough slack. Also this is another symptom. After I shift down to 1 and then I click the shifter 3 times the yellow lines in the clear window line up and instead of saying I am in 3 the shifter says I am in 4.
And as i said earlier with all this the hub seems to be working better than when I could get into 1st. There is NO noise, and no slipping.
Anyway thanks for the help. i am going to go read the only manual I can find on this hub. https://www.sheldonbrown.com/nexus8/pages/09.htm

sweeks

If you have a little slack when the shifter is in "1", and you click the thumb lever 3 times, you are in gear "4". If the adjustment lines are lining up, then all is well. You should be able to get into "8".

EDIT: You can't go wrong referring to Sheldon Brown's site. There may be information about chain length on internally-geared hubs there. Basically, as long as the "Non-Turn Washers" are able to engage the slot in the dropout, your chain is in the acceptable length zone. Shift cable tension, as noted, is unrelated.

ixcuix

Thanks. I think I am close. This is a photo of what I am talking about in regard to the dropout axle adjusters. The photo shows that even when they are adjusted all the
way to the left (facing the photo) they are still at least 1/4 in away from the NON-TURN washers. This is what makes me think I should have a shorter chain.

Thanks again Thomas

sweeks

Your "chain tensioners" aren't doing anything in that configuration. That's not a problem as long as your axle nuts are tight enough to hold the wheel in place. You *could* take a link or two out of your chain, but it's not necessary. I think those "rear-facing" tensioners in rear-opening axle slots are probably more for correctly placing (centering) the wheel if you're in a hurry. Some chain tensioner devices are called "tug nuts" (Google "bicycle chain tug nuts"), and they hold the axle from the rear of the dropout; these are especially important in forward-facing horizontal dropout slots (as you can imagine!).
If you have steel dropouts, the axle nuts may not get a good enough "bite" to hold the wheel in place if you stomp on the pedals. In that case, you probably should shorten your chain a bit. Otherwise, it seems optional to me (I don't have those things on any of my horizontal-dropout bikes, and I have no problems with wheel position).

Afterthought: It looks like that screw has a slot in the end inside the dropout, so you'd only be able to adjust it with the wheel out. Most inconvenient (unless you have access to the other end as well)! Also, don't forget that you can turn the non-turn washer 180 degrees if you need more space... for example, if you remove a link or two too many, and the chain's too tight. For starters, if you do remove links, I'd take out no more than two.

ixcuix

Right. I think I do want to be able to just slam the wheel back in after fixing a flat etc., so I will probably shorten the chain. I do not think I mentioned that a chain wear tool was used and the chain is worn out. I am also thinking about going from a 20 to a 22 or 23 tooth cog. (is this the correct word?) Anyway, my bike is shifting correctly now. I used exactly 101 mm measurement. Thanks again for all the feedback.
Thomas

Wilfred Laurier

Shortening the chain will make it more difficult to get the wheel out. The way you have it now you can move the wheel forward to slacken the chain, pull the chain off the cog or chainring, then slide the wheel out. If the chain is shorter and the chain adjustment screws in contact with the axle, you might not be able to get the chain off the gears as easily.

ixcuix

That makes a lot of sense. It is easy to get chain off and get cable off the way it is. (being able to move the axle way forward.
Not sure if I should start another thread, but what is your opinion on disassembling the NEXUS 8 speed hub and dropping the core into an ultrasonic cleaner. This is an old bilke, and I doubt this hub has ever had any mantenance, and I would like to clean it.
Thomas

sweeks

This is true. However, I have chosen to split my chain when I take the wheel off. The "quick link" is easy to remove and replace. Also, since I started using Schwalbe Marathon Plus tires several years ago, I haven't had a flat, so the only time I remove the rear wheel is to clean it or service the hub.

Question: When the wheel is to be removed without splitting the chain, isn't the procedure to move the wheel forward in the dropouts allowing the chain to be removed from the front sprocket to provide enough slack? I've never done it this way so may have it wrong.

sweeks

The Nexus hub's core (or "gear cluster" if you prefer) comes apart in several discrete and easy-to-remove modules. This first requires removal of a "C" clip, which is an "escape artist" if you're not careful! It would probably be easier to clean the modules separately. Also: *Don't* disassemble the "Axle Unit"... this is a complex piece which should be left intact. I would also recommend not taking apart the modules, as there may be "timing" issues with the planetary gears.
I've only taken the module off the axle unit once, just for the heck of it. Now all I do is open the hub and dip the gear cluster in gear oil once a year.

ixcuix

See at :56

Wilfred Laurier

I have little experience with Nexus hubs, but I have a well-worn Alfine 8 speed that has been stellar for the 10+ years I have owned it. After about two years of all-weather riding I removed the innards and dunked them into a peanut butter jar half full of ATF and noticed an immediate improvement, especially in cold weather - no cleaning necessary. I found multiple videos online of people doing this procedure and they did not, IIRC, do any cleaning baths before doing the oil dip. And I believe Alfine 8 speed and Nexus 8 speed internals are identical or close to it.

sweeks

You can also remove it with a small flat-bladed screwdriver. Just keep your hand over it so it doesn't do a runner like the one in the film. Also you should be wearing safety glasses... if that thing were to hit you in the eye there'd be hell to pay.

sweeks

AFAIK, Nexus 8 is a "low-normal" hub, while the Alfine 8 is "high-normal". Normal being the gear the hub goes to in the absence of cable tension. Otherwise they are very similar.
Some interesting information about servicing internally-geared hubs here: Aaron's Bicycle Repair .

Dan Burkhart 

The current generation of the Alfine is high normal, but previous models were low normal, same as Nexus hubs.

sweeks

Heh... I have experience with a total of two Nexus 8 hubs and one Alfine 11. Thanks for the clarification!

ixcuix

Yes. With my Jamis Commuter 3.0 I can push the axle WAY forward and just take out the cable end. By the way, the trick to doing this is to actually look how the cable end fits in the part called the cassette. To get it in or out you just have to have the cable end part alligned correctly to the hook end of the cassette. This usually means just turning it . Also I have asked many bike mechanics about if it is a good idea to use a parts cleaner to clean this Nexus Hub, and they all did not think so. Then I found this which seems right to me. I seriously doubt my hub has EVER been opened or cleaned, so i am guessing it is filthy. The bike is 10 years old. I just got it. Anyway check this out.

https://thegoldenwrench.blogspot.com/...eared-hub.html

sweeks

It is not necessary to move the axle at all to remove the cable. Shift the hub into the gear with the least cable tension. It is then possible (easy) to disengage the cable from the cassette joint (not "cassette") by pulling it forward slightly and removing it through the slot in the side of the cassette joint.
You might want to wait until you have opened the hub to decide whether or not to use a parts cleaner. The inside may be less "filthy" than you think. The ball bearings should be cleaned before re-greasing though.

ixcuix

Yes, I have taken the cable off and removed the wheel numerous times in the last week. I am pretty familiar with the easiest ways to do this
It more or less started when my cassette joint broke. The tip of the slot where the cable end goes broke off. So, i had to order a new one.
I think the next thing I am going to do is put a larger cog on the wheel and replace the chain ring and the chain.
My hub seems to be working well. No slipping of gears, and no noise. I am going to clean and lubricate it eventually though.
This link from above is by far the best info I have seen on internal hubs. Internal Gear Hub Service