Rohloff splined sprockets (and Chainglider fitment)

[martinf]

You should soon have the possibility of a 38x18, with the new splined Rohloff sprockets in 13T to 19T plus 21T and thread/spline adapter due out in March 2016.

[Hoodatder]

Hoot: There 'may' be a slight fly in the ointment.  I noticed in one of your posts you have an RST? I tried fitting a chainglider to my RST after having much satisfaction with one on the RT but it never quite worked.  It did go on but rubs against the seat stay as the clearance is quite tight. This meant that the glide was never as smooth as on the RT and I rubbed the paint off the frame.  If you try it make sure you mask the contact point and be prepared to do some surgery on the end of the glider.

Thanks martinf,

but will it address the problem mentions above? What is a splined sprocket?

Thanks

Hoot

[mickeg]

... What is a splined sprocket?

Thanks

Hoot

Rohloff is changing from a threaded on sprocket (I call it a cog) to a threaded on carrier, then you can put a splined cog on the splined carrier.

http://www.rohloff.de/en/products/speedhub/sprockets/index.html

I wish they would make a 20 tooth cog.  More teeth on the rear cog will result in less chain wear.  But I want to stay with the even number of teeth theory, so I have no interest in a 19 or 21.

http://sheldonbrown.com/chain-life.html

On the other hand, the spline system increases chainline by 4mm, mine is already off by 5mm and that would result in my chainline being off by 9mm.   I have many years to go before I need a new cog, so I have plenty of time to decide which option to use, an old style threaded on cog or a new splined carrier and cog.

[martinf]

but will it address the problem mentions above? What is a splined sprocket?

I have an RT, not an RST, so I can't be sure. The 4 mm increased chainline with the new splined sprockets might help, as the chainglider should theoretically be positioned 4 mm further out from the frame as compared to the situation with the current threaded sprockets.

One downside with the increased chainline is that a new bottom bracket unit might be necessary to move the crank/chainring out. 

[Hoodatder]

Ok, here goes,

You should soon have the possibility of a 38x18, with the new splined Rohloff sprockets in 13T to 19T plus 21T and thread/spline adapter due out in March 2016.

That's good - it fits in with Sheldon's theory of extended chain life and gives the lower gearing.

but will it address the problem mentions above? What is a splined sprocket?

But applying mickeg's theory (nay, actual practice) of using a derailleur type chain, there should be enough slap / wing;e / waggle to accommodate this slight deviation and not have the hassle / expense of another bottom bracket. Incidentally, for the avoidance of doubt, do you mean eccentric bottom bracket. That was not a facetious question.

Hoot: There 'may' be a slight fly in the ointment.  I noticed in one of your posts you have an RST? I tried fitting a chainglider to my RST after having much satisfaction with one on the RT but it never quite worked.  It did go on but rubs against the seat stay as the clearance is quite tight. This meant that the glide was never as smooth as on the RT and I rubbed the paint off the frame.  If you try it make sure you mask the contact point and be prepared to do some surgery on the end of the glider.

If fitting the splined sprocket takes it 4mm -5mm away from the seat stay, then this will eliminate the chafing and also remove the need for corrective surgery, I hope. Sometimes I think it's easier and less stressful to spec and buy another bike. Judging by the amount of moths that flew out when I opened my wallet, I consider that a sign of healthy status, although the thrupenny bits and tanners gave a modicum of concern.

Thanks all

Hoot

[mickeg]

According to this:

http://www.rohloff.de/en/products/speedhub/sprockets/index.html

The chainline on the new splined system will be 58mm.  But current chainline is 54mm (except for the 13T sprocket which is different).

Thus, your chain will be further out.  I have never tried to fit a chainglider, but I assume that this will put the chainglider closer to the seatstay and if you fit a wider bottom bracket it would be further away from the chainstay.

[Hoodatder]

Thanks mickeg,

I seem to be interpreting  everything the wrong way i.e cms for mms, sprocket way from the stay, etc. I had phase 8/9 ago of getting things crossed in my head but appearing quite normal to me in front of my eyes. The quack believed it was "burn out". Fatal, when you think I was dealing with gas and hot water!!! I thought that phased had passed, but, seemingly, in conjunction with things said and done externally to this forum that phase appears to be manifesting itself. Look out world - he's back!!

Seriously, thanks for your patience and the subtle corrections - appreciated.

Hoot

[martinf]

But applying mickeg's theory (nay, actual practice) of using a derailleur type chain, there should be enough slap / wing;e / waggle to accommodate this slight deviation and not have the hassle / expense of another bottom bracket. Incidentally, for the avoidance of doubt, do you mean eccentric bottom bracket. That was not a facetious question.

If the current chainline is spot on, a 4 mm deviation shouldn't be too bad, although I would prefer to adjust the front end, by fitting a longer bottom bracket unit, the part that fits inside the eccentric, or maybe spacers to move the current bottom bracket unit outboard if that is possible (done that without problems but not yet on a Thorn frame).

[martinf]

Thus, your chain will be further out.  I have never tried to fit a chainglider, but I assume that this will put the chainglider closer to the seatstay.

Mickeg is right and I am wrong - an increase in chainline will make fitting a Chainglider to an RST more difficult, not easier.

[John Saxby]

If I understand Rohloff's product info correctly, the "splined carrier" (article # 8540) in the parts list at the bottom of the page in the link above, fits onto an existing Speedhub, and accepts a new, splined sprocket.

If one fits the splined carrier (an "adapter", in my jargon) to an existing hub, does the chainline remain 54mm, or does it increase to 58?

I couldn't chase down the exploded-hub photo of the new adapter/splined carrier on the Rohloff site. From the photo in the link below (from a thread on crazyguy a few months back) it looked to me as if the chainline would remain constant if the splined carrier were mated to an existing hub.  Here's the link:
https://www.crazyguyonabike.com/forum/board/message/?o=tS&thread_id=670360&page=1&nested=0&v=L#670439

[Andre Jute]

If there's already interference between the seat stay and the Chainglider, an 8mm wider tread ("Q factor" for the trendies) (4mm extra per side, from 54mm to 58mm) will very likely make the Chainglider impossible to fit. The side of the Chainglider channel is definitely not more than 4mm thick, so the chain would soon be exposed.

In fact, I wonder whether, Chainglider aside, when the new Rohloff cog is fitted to  those Raven sizes which already have too little clearance to fit a Chainglider, the chain itself won't scrape against the seat stay. Perhaps one of the forum members who adjusted their Chainglider with a blade or sandpaper can eyeball the clearance and give us a definitive answer. I imagine future Ravens of those sizes will be built with clearances that take the 58mm Rohloff chainline into consideration.

DEFINITION OF CHAINLINE

It should be noted that Rohloff expects the transmission chain to be fitted with a chainline that deviates no more than 1mm from the 54mm spec; if the same applies to the new cog's 58mm chainline, a new bottom bracket and/or crankset  would be required, so that changing the cog could become expensive.

For the purposes of those who are confused about what the chainline is, which must be more than Hootadder (and certainly included me until Sheldon, blessed be his name, straightened me out), the chainline is the entire run of chain between the chainring and the rear sprocket, which should parallel the longitudinal centreline of the bike for the entire run of the chain. The chainline is taken in the centre of the chain, perpendicular to the longitudinal centreline of the bike. If there is only one chainring, the chainline runs over it, if there are two chainrings (very uncommon in Rohloff installations), the chainline is taken centrally between the two chainrings, if there are three chainrings (almost unheard of in Rohloff installations -- why would anyone do anything so stupid?), the middle chainring defines the chainline. Similar adaptations are made when more than one sprocket is fitted on the rear axle.

[mickeg]

For those of you that plan to use the new splined system when it comes out, maybe the discussion should be a new thread instead of continuing on the what is your Rohloff ratio thread.

I probably will stay with the threaded rear sprocket (or I call it a cog) instead of the new splined one and won't be using a chainglider, so good luck everyone, I am bowing out of this conversation.

[Andre Jute]

[There is already a very extensive thread on possible Rohloff chainring and cog combos at http://thorncyclesforum.co.uk/index.php?topic=4412.0 which newbies should read all the way through as I expect much of the wisdom in there will not be repeated here.] [Slight edit for continuity after splitting and merging topics -- Dan.]

Rohloff now has two different fitments of drive sprocket (screw-on and splined), with two different chainlines (54 and 58mm), and, most important, with new permissible torque ratios (Rohloff calls them "transmission factors"), 1.9 for solo riders under 100kg, and 2.5 for solo riders over 100kg and tandems.

There are thus now the pre-existing threaded sprockets with 13, 15, 16 or 17 teeth, plus splined sprockets with 13, 14, 15, 16, 17, 18, 19 or 21 teeth. The splined sprockets can be fitted to existing Rohloff hub gearboxes via an adaptor Rohloff will also supply. The splined sprockets will be cheaper than the threaded sprockets.

Splined sprocket adapter for Rohloff Speedhub 14 and splined sprocket. Photo courtesy Rohloff.

So, let's say you have a 40 tooth chainring already fitted or lurking in your spares, and you want a real stump puller of a loaded touring bike, which sprocket can you fit? 40/1.9 = 21. You can fit the 21 tooth sprocket without breaking Rohloff's rules, given you weigh under 100kg. If you weigh more than 100kg or ride a tandem, then 40/2.5 = 16, so you have to fit the 16 tooth sprocket, but you now have a choice of threaded or splined sprockets.

Here are some combos specifically sanctioned by Rolloff for sub-100kg solo riders: 32/17, 30/16, 28/15 and 26/13.

For the over 100kg solo rider and for tandems, Rohloff now sanctions 34/13, 38/15, 40/16, 42/17.

Larger chainrings can be used without limit.

Other combinations are also permitted within the torque ratios specified for the weight classes/applications, for instance by using the new 18, 19 and 21 tooth sprockets. I've given worked examples above.

The choice is now much wider. Deliveries will start in March 2016.

The only information I can currently find is the bare announcement at http://www.rohloff.de/en/news/news/news/detail/News/product-news-2016-eurobike-2015/index.html but the new torque input ratio has already shown up in the older pages for the existing threaded sprockets.

[Andre Jute]

For those of you that plan to use the new splined system when it comes out, maybe the discussion should be a new thread instead of continuing on the what is your Rohloff ratio thread.

Great minds think alike. (Mind you, my English teacher, Sam Bosman, a great man who helped shape my life with admirable wisdom, used to add, "but fools never differ.")

The new thread is at
Latest Rohloff transmission combos: which chainring and cog for you?
http://thorncyclesforum.co.uk/index.php?topic=11576.msg84230#msg84230

[John Saxby]

changing the cog could become expensive

My thoughts exactly, Andre. Ummm, we'll only need a new thread if the adapter/splined carrier mated to an existing hub changes the chainline to 58mm. Rohloff's website is coy on that matter.

I'd be interested in getting the adapter so as to fit a splined sprocket when my current threaded sprocket wears out...but I've also assumed that my sprocket, BB and knees will exit stage right more or less en groupe, ages hence, so the issue may be a cow's opinion. (A moooot point, that is.)