Offset cog on a Nexus 7 hub....

[Colyn.]

So will this 22T Behind Bars Inc. cog work on a nexus 7 hub, and if not will this Cycles US 20T cog work. They both look to be the same as the ones that come with the shimano.

http://behindbarsinc.bigcartel.com/prod ... -hoops-22t

http://www.choppersus.com/store/product ... Tires-20T/


Sent from my Samsung Galaxy SIII using Tapatalk 2

 

[socal_jack]

Those cogs appear to have much more offset than the Shimano stock cog, looks like the shifting mechanism may not work with those.

 

[Colyn.]

That's what I was thinking, the nexus 7 isn't any wider than the 3 is it? Reason I'm asking is because ill be running a 24x100mm rear wheel and the fluid frame is a tight fit. Will look like this once I install offset cog and one or two washers then 3-4 washers on the chainring to line it back up.

Sent from my Samsung Galaxy SIII using Tapatalk 2

 

[MIGZ]

They do not work on 7 speed hubs. you have to dish the hub just a little

 

[Colyn.]

Explain dishing the hub for me? Since I'm buildimg the bike from start to finish I guess this will make it easier? I'm still a noob so please bare with me.


Sent from my Samsung Galaxy SIII using Tapatalk 2

 

[ratdaddy]

taken from wikipedia
The hub flanges of modern tension-spoked bicycle wheels are always spaced wider than where the spokes attach to the rim. When viewed in cross section, the spokes and hub form a triangle, a structure that is stiff both vertically and laterally. In three dimensions, if the spokes were covered, they would form two cones or "dishes". The greater the separation between the hub flanges, the deeper the dishes, and the stiffer and stronger the wheel can be laterally. The more vertical the spokes, the shallower the dish, and the less stiff the wheel will be laterally.

The dishes on each side of a wheel are not always equal. The cogset (freewheel or cassette) of a rear wheel and disc brake rotors, if installed, takes up width on the hub, and so the flanges may not be located symmetrically about the center plane of the hub or the bike. Since the rim must be centered, but the hub flanges are not, there is a difference in dish between the two sides. Such an asymmetrical wheel is called a "dished" wheel. The side of the wheel with less dish has slightly shorter but significantly higher-tensioned spokes than side with more dish. Several different techniques have been tried to minimize this spoke asymmetry. In addition to modified hub geometry, some rims have off-center spoke holes, and the mounting of common J-bend spokes at the hub flange can be altered "inboard" or "outboard".[57]

A truing stand or a dishing gauge, can be used to measure the position of the rim relative to the hub. Thus "dishing" is also used to describe the process of centering the rim on the hub, even in the case of symmetrical wheels

http://thebiketube.com/wheel-building/h ... bike-wheel

 

[rydr1]

Please excuse my ignorance, but wouldn't the arm for the shifter cable get in the way of the deep dish cog?

Took some pics and it looks like it would at least rub on the cable. I guess someone can try it out.

 

[Colyn.]

That's exactly what would happen which is why I was asking if you could add washers to move the shifter cable out alittle away from the cog.


Sent from my Samsung Galaxy SIII using Tapatalk 2

 

[rydr1]

I'll be honest, that 7 speed looks a little intimidating to mess with. Someone with more experience will chime In and help soon...I hope. :?

That's exactly what would happen which is why I was asking if you could add washers to move the shifter cable out alittle away from the cog.


Sent from my Samsung Galaxy SIII using Tapatalk 2

 

[Rooski]

That's exactly what would happen which is why I was asking if you could add washers to move the shifter cable out alittle away from the cog.


Sent from my Samsung Galaxy SIII using Tapatalk 2

Just as Migs stated, those offset cogs will not work with a Nexus 7, due to the "shifting mechanism" (Cassette joint) being in the way, and it's not something you could just "add washers" to.

As far as a "dishing" the wheel, a better explanation would be to offset the rim towards the left (brake) side off the hub's center line. Normally, whether a wheel has to be dished or not, the rim is supposed to end up perfectly centered between the frame's left and right "stays". In order to gain chain clearance when using super wide rims, some people will purposely build their wheel so the rim is off center, towards the left side, to add clearance on the right.

Remember though, the rear triangle of the frame has to be wide enough to have the extra tire clearance, in order to off center the rim. Also, as you probably already imagined, the rear wheel will look like it's mounted wrong, due to being off center in the frame. I guess some people don't mind this, but personally, I'd opt for a narrower rim, before making my bike look all crooked.

 

[Colyn.]

No I want the wheel centered it would drive me nuts. I guess ill look for a different hub or go back to using the nexus 3... but that shifting mechanism off the side of the nexus 3 will kill the old ratty look I'm going for on my bike. Does anyone know of a 6, 7 or 8 speed (coaster brake) that a offset cog would work on without the goofy shifter mechanism. Trying to keep this bike simple (no brake lines, no shifter cables unless mounted right infront of hub)....

The cables kill the bike IMO...


Sent from my Samsung Galaxy SIII using Tapatalk 2

 

[Tater]

You can add a spacer between the locknut and cone nut on the non-drive side of the hub thereby increasing the over locknut dimension of the hub. This will keep the wheel centered in the stays once it is laced up and push the cog outward as you desire. Spread the stays as needed and lace the wheel centering the rim between the locknuts and you will be good to go. The spacer length will need to be twice the desired cog offset dimension.

 

[Colyn.]

I will have to look... I was gonna get all parts before frame but I'm thinking now to order frame first. I'm stuck on which hub. Hate nexus 3 because of shifter mechanism but doesn't seem like ill be able to run the nexus 7 with 100mm wheel....


Sent from my Samsung Galaxy SIII using Tapatalk 2