[Part 2] Rohloff splined sprockets (and Chainglider fitment)

[John Saxby]

I imagine it's due to the minimum order run for producing the sprockets and the low number of sprockets they would sell in comparison

Dave knows a lot more about the economics of producing Rohloff sprockets than I do, so his reading of Rohloff's decision seems plausible.  For now.  But for how long?

I'd guess that within a decade, we'll be able to produce 16T & 17T threaded sprockets on a 3D printer -- what does that possibility do to the conventional arithmetic of production costs & production runs?  Seems to me that, if we've made an investment in frames and hubs that are likely to last for at least a couple of decades, then I'd expect Rohloff and Thorn to track the development of that technology, with a view to licensing production of small batches of the necessary parts.

Extending the logic, what prospects for Hebie licensing 3D printer production of small batches of a 'glider for 36T chainring?  Surely that possibility must be closer than a decade away?

[David Simpson]

I still don't see the huge difficulty in Rohloff selling two carriers - one for the 13 & 15t sprockets, and a narrower one for the 16 & 17t sprockets.

I was thinking this same thing myself.

If Rohloff won't, maybe some third party (Thorn/SJS?) could. Thorn/SJS already sell the 19T sprocket, to fill in a gap in Rohloff product line, so there is already a precedence.

- Dave

[Dave Whittle Thorn Workshop]

I was thinking this same thing myself.

If Rohloff won't, maybe some third party (Thorn/SJS?) could. Thorn/SJS already sell the 19T sprocket, to fill in a gap in Rohloff product line, so there is already a precedence.

- Dave

Ok the minimum order run for a new sprocket size from our subcontractor is 500, so if you can get together with an order for 250 of them, I can probably convince Robin to take the risk on the other 250....

[Danneaux]

Possible order list for Dave and Thorn...

To gauge demand, please list how many of each size custom-made threaded sprockets you would actually order. Please be sincere so Thorn is not left holding the bag if they go ahead on contracting for these:

Tooth size:

Quantity:

Best,

Dan.

[mickeg]

Thanks for checking but since I would want a 16T and probably nobody else would, count me as not wanting any. 

I am still assuming that when the new ones come out, the older threaded ones will be on a clearance sale from some retailers.

I hope when the splined ones come out that we will be able to put a sprocket on there that has the same spline pattern as something else, perhaps a sprocket from a cassette for a 8 or 9 speed Shimano freehub.  Or maybe an old Suntour five or six speed freewheel.  Or a Sturmey Archer.

[John Saxby]

Thanks, Dave and Dan. Mine's already ordered and awaiting pickup at SJSC next week. A good idea in principle, but I'm now fixed up for the duration :-)

[David Simpson]

I appreciate the Thorn/SJS offer. However I just ordered a lifetime supply of sprockets for my hub.

- DaveS

[martinf]

If I'm not too lazy, I'll probably just order a couple of spare 17T sprockets while SJS still have stock, that should be enough to keep me going for several years use.

But the solution I would like to see is a redesigned carrier to allow fitting the new splined sprockets in either the current 54 mm chainline position or the new 57 (or 58) mm chainline position.

I think this could be achieved fairly simply (in manufacture, less easy if trying to adapt the standard part by DIY) by machining the carrier splines to an extra 3 or 4 mm depth, then adding two thin spacers (1.5 or 2 mm each). Unless there is a good engineering reason not to do this.

This would be similar to the system on the old Sturmey-Archer drivers on my S5/2 hubs, which allow quite a lot of chainline adjustment and even (with a bit of grinding) the use of two sprockets.

In addition to enabling those of us that have the old sprockets to continue using the same bottom bracket width (and perhaps Chainglider), a sprocket carrier redesigned  as above would have the advantage of allowing small chainline adjustments at the hub for 16T and bigger, while maintaining the use of one design of carrier for all sprocket sizes (spacers must be inboard for the small 13, 14 and 15T sprockets, choice of both inboard, both outboard or 1 inboard and 1 outboard for larger sprockets).

[il padrone]

Yes. Well I put in an order last week when I twigged to the implications

Thanks Dave and SJS. I have now received the shipment and have sprockets for the next 15-20 years 

[il padrone]

If I'm not too lazy, I'll probably just order a couple of spare 17T sprockets while SJS still have stock, that should be enough to keep me going for several years use.

But the solution I would like to see is a redesigned carrier to allow fitting the new splined sprockets in either the current 54 mm chainline position or the new 57 (or 58) mm chainline position.

I think this could be achieved fairly simply (in manufacture, less easy if trying to adapt the standard part by DIY) by machining the carrier splines to an extra 3 or 4 mm depth, then adding two thin spacers (1.5 or 2 mm each). Unless there is a good engineering reason not to do this.

Machining IS an option, but not something as convoluted as machining the splines. Going by the described design, you should simply need to machine off 4mm (3mm - this chain-line difference is still not clear??) off the inner face of the sprocket carrier. This will place the whole carrier 4mm to the left to re-instate the chain as per the current sprocket design.

[Andre Jute]

Thanks for checking but since I would want a 16T and probably nobody else would, count me as not wanting any.

16T was the Rolloff default sprocket size, supplied with every Rohloff unless an OEM (Thorn for instance) asked for a different tooth count.

I can't make up my mind whether that means:

a) That there will be a more stocks of 16T sprockets and therefore those of us with an investment in 16T sprocket setups have nothing to worry about

OR

b) there will be a permanent high demand for 16T sprockets, so that the existing stocks will quickly disappear.


Whichever it is, by the end of next week I'll have enough 16T threaded sprockets to see my grandchildren right.


That's a public service Dave Whittle performed by warning us about these shenanigans at Rohloff, so that we could stock up.


***


As it happens, I can't see why the roadies go on about a narrow tread, or why a wide tread is so often blamed when a cyclist ruins his knees. I positively prefer a wide tread, and I could very likely learn to live with a 58mm Q factor on my Rolloff-equipped bike, if everything else were equal. But everything else is never equal, and, as I've said already, if push comes to shove in the spatial dimension (heh-heh), I'd give up the Rohloff before I'd give up the Chainglider.


***


Yo, Pete, you've clearly made a calculation, so how many sprockets have you laid in for the twenty years you mention?

[JimK]

I just bought a couple 16 tooth spares. Given that the chainglider keeps things clean so they last longer... well, who knows, that might be enough for the duration!

[John Saxby]

by the end of next week I'll have enough 16T threaded sprockets to see my grandchildren right.

I just bought a couple 16 tooth spares

I have now received the shipment and have sprockets for the next 15-20 years

I just ordered a lifetime supply of sprockets for my hub

Mine's already ordered and I'm now fixed up for the duration

Ah, jeez, now the truth is out, for any casual passer-by to see: we're all just hoarders, stocking up on collectors' items. Polished, and with a few gouges for authenticity, they'll make good retro-chic jewellry, conversation pieces for the grandkids.  "Wow, grandpa -- you used that? You musta bin some dude, back in the day!"

[il padrone]

Yo, Pete, you've clearly made a calculation, so how many sprockets have you laid in for the twenty years you mention?

I bought a couple of 17t, a 16t and two Thorn 19T sprockets. Given that I've just replaced the whole drivetrain 6 months ago after 4.5 years of use, I reckon between these I should have at least 20 years. The 16t should be handy when my wife wears hers out (she has 40-16, while I have 42-17 - almost exactly the same gear), then later on, if things get too weary for the old legs the 19t sprockets could allow a low gear range sans-Chainglider.

[il padrone]

Ah, jeez, now the truth is out, for any casual passer-by to see: we're all just hoarders, stocking up on collectors' items. Polished, and with a few gouges for authenticity, they'll make good retro-chic jewellry, conversation pieces for the grandkids.  "Wow, grandpa -- you used that? You musta bin some dude, back in the day!"

Nah, I'll save one or two of the old worn ones for that - much more cred. Just hope that I can get one like Pete Gostelow has