tiger1964 

Any Nexus 8 experts out there?

For my latest project, I ordered wheels with a Nexus 8 hub, about which I know nothing; and hooking up the shifting capability is the end of the project. I just watched a short video on installing the "cassette" which is how the cable pull actuates the gear shifting inside the hub -- OK, it does look "doable". Now, instead of a shifter on the bars somewhere and housing all the way to the hub -- now I finally mixed enough parts for a Nexus-friendly shifter, but mounted on the downtube. With an open run to the bottom bracket, and passing on an under-the-shell guide, and then to a to-be-installed stop on the chain stay, it's almost all open run cable with no housing. The only housing would be from the chain stay stop to the end of the arm on the cassette (and I am uncertain how I can include an adjusting barrel!), just a couple of inches, and any lateral deflection ("Z"-ing) of that housing to align the two ends might have to happen in a very short distance. Problem?

So, here's my question, and it's clear I really do not know what's going on inside the hub. What's to stop me from rotating the wheel so that the housing-stop arm on the "cassette" no longer points down and towards the front of the bike... but instead points up and back? Then I can run a longer loop of housing from the chain stay stop, back past the axle and then through 180 degrees to meet up with the arm on the cassette (so it would look a bit like the housing loop on a rear derailleur installation). It can bolt it all up that way, but would the internals still shift, and would I be starving anything of lubrication in there?

Winfried

Not sure what the goal is, but pointing the cassette joint's arm backwards has been done on a Brompton when using Shimano non-turn washers instead of Sturmey-Archer's (which work fine) :

tiger1964 

Mostly having a good functional housing loop instead of sharp friction-inducing bends.

That may tell me what I need to know -- If that user's hubs worked, and continued to work. Wow, that's the most inelegant cable routing on record, but if it did the job... that's what I need to know.

Dan Burkhart 

You can change the orientation of the cassette joint by using different anti rotation washers or sometimes swapping them left for right will point it where you want it to go. I have one of my Nexus hub bikes set up with the cassette joint pointed up the seat stay so I could use the top tube mounted cable stops. I have done other builds this way in the past and it works fine.

tiger1964 

thanks! By the way, I now have three different pairs of washers. So, I have options but the manual really does not state which orientation of the axle is desired. The flats on the axle, do they go vertical, horizontal, or what?

sweeks

As Dan has pointed out, you determine the best orientation for your cassette joint, then select the non-turn washers that hold the axle in the correct orientation. These washers must be used in pairs with the same number, but they may be swapped right-for-left to get the best orientation.

tiger1964 

again, thanks, but I presume I am asking the question incorrectly. What, exactly, IS the correct axle orientation? If the axle flats only had to be parallel to the dropout slots, in this case old Campagnolo dropouts at perhaps twenty degrees to the ground, then there would only be one type of washers to hold the axle at zero degrees to the dropout. So, what is the goal? Parallel to the ground? Perpendicular?

Dan Burkhart 

The axle doesn't care. What matters is that the cassette joint is properly installed and it is pointed to where you want it to go.

tiger1964 

OK, perhaps this makes more sense. I have not installed the cassette yet, but maybe when I do, the relationship between the direction the cassette arm points and the direction of the axle flats becomes FIXED, and then the washers help point the cassette arm in the correct direction. True?

sweeks

The flats wind up at whatever position the non-turn washers put them in. This allows the cassette joint to point in a convenient direction. It's as simple as that!

sweeks

You need to put the wheel in the frame with the cassette joint mounted in order to determine the best orientation for the joint. Then select the washers that keep the axle and cassette joint in that position.

tiger1964 

Thanks! OK, I watched a video on installing the cassette, and I think I was successful. As I think there is no way to effectively aim the cassette arm down and forward due to far too short a run of housing until the chainstay stop, I am still thinking of aiming it up and straight back. Thus the correct washers seem to be the 7L/7R grey and black, as the axle flats are nearly vertical.

i have another question. I have the cassette in place, but it seems to me that the cassette has a tiny bit of wiggle once installed, perhaps 1/16” left to right, and there is even a tiny bit of play in the yellow-dot locking ring but is disinclined to back off. Is this play normal? If not, where would one adjust it out?

Dan Burkhart 

Once it is snapped in place there is no adjustment. A tiny bit of lash is normal, and desirable as it indicates proper installation with no binding.

tiger1964 

Thank you, that sounds right and I can proceed, I stopped working on the bike in case I needed to disassemble and start over.

i think I may have a solution for no place for an adjuster. I had read elsewhere (I usually hang out on Thr classic and vintage forum) about something called an in-line adjuster. Looking online, I see Jagwire makes them and I have ordered the 5mm version. Hopefully this will work, installed in the loop from the chain stay stop to the cassette.

Dan Burkhart 

If you are using a shifter without a barrel adjuster, an inline adjuster is necessary. I have done this with builds using Jtek shifters.

tiger1964 

Thanks for the confirmation of what I had kind of figured out on my own in the first place. I have been corresponding with the company that built my wheels including the Nexus 8 hub. In addition I have been corresponding with Microshift who made the shifter. Originally it was designed to be a bar-end shifter but I’ve been able to adapt it to downtube application. There is simply no place except for the final loop for any housing to install an adjuster. Nowhere did I read that it was desirable to use an in-line barrel adjuster and that would’ve saved me a lot of time if I had known in the first place.

sweeks

Be sure to shift to the gear with the least cable tension before making adjustments; then increase tension up to the gear (4) where the adjustment is checked.

tiger1964 

Looking a the twist-grip shifter that came with the hub/wheels but unused, I figured out that position #1 is "most relaxed" and position #8 is "most tension". So, all the way forward on my hybrid downtube shifter for lowest gear, all the way back for highest gear. Kinda like my Simplex 543! Inline adjuster just showed up -- wish me luck.

sweeks

Yes. So start in position "1" and advance to "4" and check your hub mark alignment. If it's off, go back to "1" and adjust your in-line device. Then go back to "4". And so on until the marks line up in Gear 4.

tiger1964 

Thanks, it all worked despite my odd chosen orientation of the cassette, and the bike is "complete" and I rode it a few hundred meters but that's it. Very intricate installation! By the way, I do not see a way to adjust it but the cable inner wire, on the path from housing end on the cassette arm going to the hub itself, clears the chain by 1 to 2 millimeters. It is so tempting to bend the arm a bit for some peace of mind, but...

sweeks

If you are referring to the cassette joint's proximity to the chain, that is not a problem as long as they don't rub while riding. Clearances are pretty tight.
If it's the alignment of the marks on the cassette joint, that is controlled by your in-line cable adjuster.
I assume it's the former?
Nice creative placement of the cable and cassette joint!

tiger1964 

Yeah, it's the former; there's no protection for that exposed inner wire and I'd almost need a feeler gauge to determine how little air space there is between the wire and the chain.

Thanks, and that was the original object of the topic. It has been pointed out to me that if I could find a chain stay housing stop that was big enough to fit much farther forward, where the chain stay is much fatter, I could turn the cassette around to a more conventional position and a length of housing perhaps just short enough for the adjuster, etc.

tcs

https://www.sturmey-archer.com/en/pr...ke-and-fulcrum

tiger1964 

Thanks, I'll check that out. I presume it's OK to use something like that, specifically the plastic insert, with compressionless housing? They are not the most elegant-looking clamps but it's something. I guess in retrospect I could have had a stop brazed on at a frame-builder's prior to the powder coating, but it is too late for that now.