Rohloff splined sprocket internal diameter?

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Volvofan   1 mW

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Rohloff splined sprocket internal diameter?

Post by Volvofan » Apr 18 2020 11:42am

Fellow ebike enthusiasts-

As this is the ONLY bicycle forum for which I am registered, I thought I would start here with my inquiry.

I’m considering adding a TDCM IGH rear hub motor to my M2S All-Go Carbon. Would also like to use a belt drive. Have to go with VEER split belt vs Gates because I don’t want to split my all-CF frame. The TDCM IGH has a 5 speed Sturmey Archer IGH built into it, for those who may be unfamiliar. Veer only makes rear sprockets for the 3-speed S-A, the Enviolo, and the Rohloff.

Looking at the Rohloff rear sprocket from VEER, it’s a solid unit, so, I could theoretically hog out the hole in order to make it fit a 5-speed S-A. After nearly two hours of combing the internet, though, I came up empty in finding the minimum internal diameter of a typical Rohloff rear sprocket. Not concerned with its splines... just if you were to slide the sprocket over a perfectly round cylinder, what would be the max diameter the cylinder could be before the sprocket wouldn’t fit? This small - yet elusive - critical dimension will tell me whether I would have enough “meat” on the body of the sprocket to work with for my custom application.

Might someone have one, and a pair of calipers, handy? If so, could ya do me a solid and take a quick measurement? Trying to get a feel for whether this is a feasible idea.

Thanks in advance!

-Jon
RIDE: M2S All Go Carbon, 36v 350W Bofeili crank, ABT-800 display, 27.5" whls, 20-spd, hyd. disc brakes
LIGHTING: 6-LED headlight bar, LED F&R running light strips, Photon R60 brakelight, Firefly TS grips
ACCESSORIES: Montague Rackstand, Hornet horn, water bottle, top rail toolbag, Coros SafeSound helmet
CUSTOM: Vinyl wrap, cell phone stem mount w/ wireless charging, and wiring/cabling cleanup

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amberwolf   100 GW

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Re: Rohloff splined sprocket internal diameter?

Post by amberwolf » Apr 19 2020 4:02am

Perhaps I don't understand which dimension you need, because the sprocket information appears to be right here:
https://www.rohloff.de/en/experience/te ... ifications
Sprocket thread: M34x6 P1, tolerance 6H
for all versions I can see.

So the M number is the metric size (diameter) of the threading, the x number is the metric width of the threaded portion, the P number is the thread pitch and the tolerance is (I think) how different the thread cut might be from the ideal and still work.

Your best bet is, of course, to contact VEER directly and ask to be certain the part could be used the way you want.

Volvofan   1 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Volvofan » Apr 19 2020 7:53am

Sorry about that! It is obvious to me what I’m looking for because I’ve been staring at it for hours, but I had a feeling my description would fall short. I did not post photos because I was being lazy but I know a pic is worth a thousand words, so... see below.

Rohloff’s site was the first one I went to. Lots of specs on that page, but not the one I’m looking for.

I doubt Veer would be helpful in advising me on how to hack up one of their products and employ it in a manner not intended by the manufacturer, lest they incur liability should something go awry (though I am not the litigious type).

Basically, I just need to know how much “meat is on the bone” of Veer’s Rohloff sprocket, specifically, but ANY Rohloff sprocket will be able to provide me the answer. If it’s 46.5mm or smaller, I should be all set. I can remove material via saw/file/dremel/whatever to make the Rohloff sprocket fit a 5 speed SA (which has a nominal internal diameter of 50mm, with an internal diameter to the tips of the three splines of 46.5mm). If the Rohloff sprocket’s ID is any larger, I’d need to ADD material to get it to fit, vs. removing it. In other words, my proposed low-tech Macgyver solution would go bye-bye.

-Jon
0426C095-F660-4F9A-AFC6-AE6E80E1AB98.jpeg
What is THIS dimension?
0426C095-F660-4F9A-AFC6-AE6E80E1AB98.jpeg (259.89 KiB) Viewed 278 times
87CEE995-D6D7-4801-AB18-8624242E2BAF.jpeg
Removing material from Veer’s SA sprocket would likely compromise its structural integrity.
87CEE995-D6D7-4801-AB18-8624242E2BAF.jpeg (274.02 KiB) Viewed 278 times
244E41F1-06EA-485E-BBD6-12330CE44BC2.jpeg
Veer’s Rohloff sprocket has a solid hub. If it’s got a small enough ID, I should be able to remove material to make it fit a SA 5-speed
244E41F1-06EA-485E-BBD6-12330CE44BC2.jpeg (201.52 KiB) Viewed 278 times
RIDE: M2S All Go Carbon, 36v 350W Bofeili crank, ABT-800 display, 27.5" whls, 20-spd, hyd. disc brakes
LIGHTING: 6-LED headlight bar, LED F&R running light strips, Photon R60 brakelight, Firefly TS grips
ACCESSORIES: Montague Rackstand, Hornet horn, water bottle, top rail toolbag, Coros SafeSound helmet
CUSTOM: Vinyl wrap, cell phone stem mount w/ wireless charging, and wiring/cabling cleanup

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amberwolf   100 GW

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Re: Rohloff splined sprocket internal diameter?

Post by amberwolf » Apr 19 2020 11:55am

Then you already have the needed info, in the data from rohloff, as long as you also know the minimum amount of metal required to leave between the ID and the belt teeth. :-)

The "M34" dimension is the necessary data.

Volvofan   1 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Volvofan » Apr 19 2020 1:20pm

Sort of... but not precisely.

The hub has a splined sprocket “carrier” that threads onto the hub itself; that carrier is not zero mm thick.

Just eyeballing it, I “THINK” I’d be just fine, but would rather have someone with a set of calipers help me remove all doubt :)
CC0A5E12-3A25-4AFD-B1C2-377EE882B46C.jpeg
The internal (threaded) diameter is approx. 34mm, but the external (splined) diameter is _____??? Depends on how thick the carrier is. If about 6mm thick or less... I should be good to go.
CC0A5E12-3A25-4AFD-B1C2-377EE882B46C.jpeg (464.42 KiB) Viewed 266 times
RIDE: M2S All Go Carbon, 36v 350W Bofeili crank, ABT-800 display, 27.5" whls, 20-spd, hyd. disc brakes
LIGHTING: 6-LED headlight bar, LED F&R running light strips, Photon R60 brakelight, Firefly TS grips
ACCESSORIES: Montague Rackstand, Hornet horn, water bottle, top rail toolbag, Coros SafeSound helmet
CUSTOM: Vinyl wrap, cell phone stem mount w/ wireless charging, and wiring/cabling cleanup

Grautuefel   100 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Grautuefel » Apr 19 2020 7:35pm

Hi mate,

If you can wait until the weekend I have calipers and a rohloff that I need to service, so win win. I'll read the thread more thoroughly and PM you Saturday (australian time) if I have any questions

Volvofan   1 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Volvofan » Apr 19 2020 8:34pm

Thanks so much! I am definitely not pulling the trigger on any purchases in the next week or two, so I’m in no rush and would be grateful for the assistance!

Stay safe and healthy,

-Jon
RIDE: M2S All Go Carbon, 36v 350W Bofeili crank, ABT-800 display, 27.5" whls, 20-spd, hyd. disc brakes
LIGHTING: 6-LED headlight bar, LED F&R running light strips, Photon R60 brakelight, Firefly TS grips
ACCESSORIES: Montague Rackstand, Hornet horn, water bottle, top rail toolbag, Coros SafeSound helmet
CUSTOM: Vinyl wrap, cell phone stem mount w/ wireless charging, and wiring/cabling cleanup

Grautuefel   100 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Grautuefel » Apr 19 2020 9:07pm

Right, you want the OD (marked in blue) of the lumpy round doohicky. Got it

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Re: Rohloff splined sprocket internal diameter?

Post by Volvofan » Apr 19 2020 9:43pm

Grautuefel wrote:
Apr 19 2020 9:07pm
Right, you want the OD (marked in blue) of the lumpy round doohicky. Got it
Yes, please! That’s the technical terminology I was lacking, too ;)

Thanks again!

-Jon
RIDE: M2S All Go Carbon, 36v 350W Bofeili crank, ABT-800 display, 27.5" whls, 20-spd, hyd. disc brakes
LIGHTING: 6-LED headlight bar, LED F&R running light strips, Photon R60 brakelight, Firefly TS grips
ACCESSORIES: Montague Rackstand, Hornet horn, water bottle, top rail toolbag, Coros SafeSound helmet
CUSTOM: Vinyl wrap, cell phone stem mount w/ wireless charging, and wiring/cabling cleanup

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amberwolf   100 GW

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Re: Rohloff splined sprocket internal diameter?

Post by amberwolf » Apr 19 2020 10:10pm

Volvofan wrote:
Apr 19 2020 1:20pm
The hub has a splined sprocket “carrier” that threads onto the hub itself; that carrier is not zero mm thick.
Ah, I did not see that the carrier was separate from the sprocket itself on the Rohloff site or any of the cutaway drawings out there. It appeared to be a single unit that threaded on as one piece. :oops:

It's probably irrelevant since he's offered to caliper it for you, but a guesstimate can be made, using an image editor (like paint in windows) that shows you what pixel number your cursor is on at any given moment:

The red bracket line in your pic above would be 34mm. The diameter this line marks is about 830 pixels wide, and the space between it and the outside of the ring where the blue line marks is about 35 pixels.

So if 34mm = 830pixels, or 0.041mm/pixel.

0.041mm/pixel x 35 pixels = 1.44mm.

There's two of those thicknesses, so that's about 3mm more for the OD, to add to the 34mm ID.

So the OD is approximately 37mm, plus or minus a mm or so, for a possible range of 36mm to 38mm.

Assuming I can do math right now, which is not always guaranteed. ;)

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Re: Rohloff splined sprocket internal diameter?

Post by Volvofan » Apr 19 2020 10:27pm

amberwolf wrote:
Apr 19 2020 10:10pm
Volvofan wrote:
Apr 19 2020 1:20pm
The hub has a splined sprocket “carrier” that threads onto the hub itself; that carrier is not zero mm thick.
Ah, I did not see that the carrier was separate from the sprocket itself on the Rohloff site or any of the cutaway drawings out there. It appeared to be a single unit that threaded on as one piece. :oops:

It's probably irrelevant since he's offered to caliper it for you, but a guesstimate can be made, using an image editor (like paint in windows) that shows you what pixel number your cursor is on at any given moment:

The red bracket line in your pic above would be 34mm. The diameter this line marks is about 830 pixels wide, and the space between it and the outside of the ring where the blue line marks is about 35 pixels.

So if 34mm = 830pixels, or 0.041mm/pixel.

0.041mm/pixel x 35 pixels = 1.44mm.

There's two of those thicknesses, so that's about 3mm more for the OD, to add to the 34mm ID.

So the OD is approximately 37mm, plus or minus a mm or so, for a possible range of 36mm to 38mm.

Assuming I can do math right now, which is not always guaranteed. ;)
Indeed! I love the “count pixels in MS Paint” solution for rough estimates, though I trust the “caliper in one hand and part in the other” method even more. Even if your/our estimate is off by 100% (ie part is 6mm thick instead of three) I’m still looking at 46mm, which is more than sufficient.

Thanks for the help, all!

-Jon
RIDE: M2S All Go Carbon, 36v 350W Bofeili crank, ABT-800 display, 27.5" whls, 20-spd, hyd. disc brakes
LIGHTING: 6-LED headlight bar, LED F&R running light strips, Photon R60 brakelight, Firefly TS grips
ACCESSORIES: Montague Rackstand, Hornet horn, water bottle, top rail toolbag, Coros SafeSound helmet
CUSTOM: Vinyl wrap, cell phone stem mount w/ wireless charging, and wiring/cabling cleanup

Grautuefel   100 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Grautuefel » Apr 24 2020 10:04pm

OD is exactly 40mm.

Wall thickness min is 2mm max is 3mm

All lovely and metric. Is German after allImage

Volvofan   1 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Volvofan » Apr 24 2020 10:12pm

Grautuefel wrote:
Apr 24 2020 10:04pm
OD is exactly 40mm.

Wall thickness min is 2mm max is 3mm

All lovely and metric. Is German after allImage
Beautiful! I ordered the Veer kit and the hub already. Frame clearance is gonna be tight, and belts leave little room for error in that regard. I’ll have 99 problems getting this to work properly, but it’s good to know that having a rear sprocket I can adapt ain’t one :)

Thank you once again!

-Jon
RIDE: M2S All Go Carbon, 36v 350W Bofeili crank, ABT-800 display, 27.5" whls, 20-spd, hyd. disc brakes
LIGHTING: 6-LED headlight bar, LED F&R running light strips, Photon R60 brakelight, Firefly TS grips
ACCESSORIES: Montague Rackstand, Hornet horn, water bottle, top rail toolbag, Coros SafeSound helmet
CUSTOM: Vinyl wrap, cell phone stem mount w/ wireless charging, and wiring/cabling cleanup

Grautuefel   100 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Grautuefel » Apr 26 2020 5:34pm

I hate you. I'd given up on belt drive and you've got me looking at this split belt system. If I can get away from noisy dirty chains it would be wonderful.

Volvofan   1 mW

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Re: Rohloff splined sprocket internal diameter?

Post by Volvofan » Apr 26 2020 6:37pm

Grautuefel wrote:
Apr 26 2020 5:34pm
I hate you. I'd given up on belt drive and you've got me looking at this split belt system. If I can get away from noisy dirty chains it would be wonderful.
Happy to be of service :)
RIDE: M2S All Go Carbon, 36v 350W Bofeili crank, ABT-800 display, 27.5" whls, 20-spd, hyd. disc brakes
LIGHTING: 6-LED headlight bar, LED F&R running light strips, Photon R60 brakelight, Firefly TS grips
ACCESSORIES: Montague Rackstand, Hornet horn, water bottle, top rail toolbag, Coros SafeSound helmet
CUSTOM: Vinyl wrap, cell phone stem mount w/ wireless charging, and wiring/cabling cleanup

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