# Purely hypothetical, but what about a rohloff and hammerschmidt



## iridexc (Sep 21, 2008)

the idea of a 28 speed drivtrain without a single tensioner or derailleur is rather enticing if only on a hypothetical level, has anyone considered or done this?


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## itsdoable (Jan 6, 2004)

The recumbent crowd have been putting a Schlumpf Speed-Drive (predecessor to the Hammerschmidt) with a Rohloff for years. You don't get a lower gear, but you get higher ones.


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## slocaus (Jul 21, 2005)

I am in the very early stages of a Alfine concept, and have toyed with the idea of adding a Hammerschmidt for lower gearing. I saw some of the prototypes last fall, when all the Truvativ guys came out for a trail work day. Looks sweet.


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## pursuiter (May 28, 2008)

iridexc said:


> the idea of a 28 speed drivtrain without a single tensioner or derailleur is rather enticing if only on a hypothetical level, has anyone considered or done this?


There's lots of duplicates so you won't get the full 28 speeds, same issues with the Alfine.

I did the calculation for Alfine, you get 3 more gears on the high end and lots of duplicates.


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## MABman (Oct 5, 2008)

itsdoable said:


> The recumbent crowd have been putting a Schlumpf Speed-Drive (predecessor to the Hammerschmidt) with a Rohloff for years. You don't get a lower gear, but you get higher ones.


With a Mtn. Drive you do get a lower gear, ran one on a couple different FS bikes with an 11/32. The extra low gear helped get them up in to the high country many a time without complaint. I still have that MD and need to get rid of it here some day as I don't ride the big travel stuff anymore and passed the Moth on to my son who does.

Florian shared a booth with Rohloff in Vegas while the hammer thing had a circus act promoting theirs. If I was going with a Rohloff I would go with the Schlumpf. Time tested, proven and cheaper, although not by much.


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## MABman (Oct 5, 2008)

The old double post. Carry on.


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## itsdoable (Jan 6, 2004)

MABman said:


> With a Mtn. Drive you do get a lower gear, ran one on a couple different FS bikes with an 11/32.


The problem with the Mountain-Dive is it gears down the front chainring by 2.5x - which makes it difficult to maintain Rohloff's 2.4:1 ratio, you need a 95t chainring to stay "legal" with a 16t cog. The MountainDrive effectively makes a 44t chainring act like a 17.6t chainring. Most IGHs have limits on the lowest gearing - but oddly enough, the MountainSpeed was designed to double the range of a standard 3-speed IGH by adding a lower 3-gears evenly spaced. The main use was recumbents, which typically did not load the hubs excessively.



MABman said:


> If I was going with a Rohloff I would go with the Schlumpf. Time tested, proven and cheaper, although not by much.


I have a Schlumpf speed-drive, and it's nice. The main advantage of the SRAM version is the shifting, some people may not like the heel shifter on the Schlumpf. Also, ICG verses chamfering your BB shell, although the triebwerk version is nice.



pursuiter said:


> There's lots of duplicates so you won't get the full 28 speeds, same issues with the Alfine.


Same is true with a dérailleur system, but they still call it a 27-speed.

MABman, let me know if you are getting rid of your Mountain-Drive, I think I have a good use for it.


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## MABman (Oct 5, 2008)

Actually it is 2.25:1. 

Here is some info on why the Recumbers use it and don't forget they use 20" wheels.

With a 20" rear wheel using an 11-34T rear cassette and two front chainring sizes of 53T and 39T, you can expect a gear range of approximately 8.6 - 90 gear inches, with a fair bit of overlap (that is NOT a typo).

The standard Mountain-Drive comes with a chainring. One or two side chainguards / trouser-guards can be added. The standard bolt drilling is 130bcd (pcd), but the Speed-Drive can be ordered with a 110 bcd bolt patter to fit the smaller 110 pcd chainring sizes.

Althought Rohloff officially recommends against it, recumbent trike riders looking for a huge gear-range while eliminating the fuss of derailleurs can effectively use the Schlumpf MountainDrive in conjunction with the Rohloff Speedhub. On a trike with 20" wheels, the following gearing ranges would be reasonable (Chainring-53/Cog-13 -> 8.5-112 gear inches or Chainring-65/Cog-15 -> 9.1-119)


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## rockyuphill (Nov 28, 2004)

MABman said:


> If I was going with a Rohloff I would go with the Schlumpf. Time tested, proven and cheaper, although not by much.


Not to mention that the Schlumpf Mtn Drive doesn't need ISCG mounts on the BB shell.


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## itsdoable (Jan 6, 2004)

MABman said:


> Actually it is 2.25:1.


Humm..., I remember 2.5x way back when I communicated with Florian, and his website still says 2.5:1. Maybe earlier ones were 2.25x?

The torque limit on the Rohloffs 250NM at the crank with a 2.4:1 ratio, regardless of wheel size (it's based on maximum torquer the hub can take). Since you cannot stand and mash on a recumbent (well, not easily anyways), the feeling is you should be able to go to a lower ratio without exceeding the max torque (that, and many people exceed this ratio without any issues). And since you can't stand, a lower gear is useful for steep hills - at the same time, since you can descend faster (less wind resistance), a higher gear is also useful.

This is not true of typical mtb's that the OP asked.


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## MABman (Oct 5, 2008)

Hey, I was just posting some copy, take it as you will. I do know that I used mine successfully on the 29"er FS bikes as seen on here earlier. Had a real nice ditch gear and a 40/11 with only a few overlaps at the crux. 

These units last forever with a meager diet of the grease that Florian provides injected once every 1000k/year or so. My oldest Schlumpf speed drive has been greased 9 times now and works even better now as it is worn in some and has little noticeable drag which a new one will exhibit, but not to the point of distraction.


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## estutjaweh (Jan 3, 2008)

Its not possible unfortunately.

The SPEEDHUB will not work in conjunction with a Hammerschmidt crankset because the transmission that is produced undercuts Rohloffs permitted primary transmission ratio. This basically means that there will be an ingoing torque that measures more than the allowed 100N at the sprocket.

The idea of additionally mounting the Hammerschmidt with the SPEEDHUB is also fairly pointless. The result will be a combination of gear ratio "doubles" as with a typical derailleur gear system. These gear combinations are therefore simply extra weight that is carried around lowering the working efficiency of the system. Combining a SPEEDHUB with the Hammerschmidt or with 2 chainrings offers in reality only 1 or 2 (depending upon the chainring/sprocket combination) extra usable gears.


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## scuppy (Nov 10, 2007)

Well I'm running 80W gear oil in my Rolhoff and produce more torque than I'm supposed to. Hang on there's someone at the door...


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## itsdoable (Jan 6, 2004)

MABman said:


> Hey, I was just posting some copy, take it as you will. I do know that I used mine successfully on the 29"er FS bikes as seen on here earlier....


Hey, I'm just pointing out that using the Mountain Drive with a _Rohloff_ will void your warrenttee, and considering the cost of those units, most people are conscientious about that. You're 29er is dérailleur based, which is fine for the MountainSpeed.

My SpeedDrive is ~7 years old, been on at least 3 bikes, and I don't think I've greased it yet. Florian make some nice stuff, and if I wanted something like the HammerSchmidt (with bar shifting) I'd probably look at the Triebwerk one first.



estutjaweh said:


> Its not possible unfortunately.
> 
> The SPEEDHUB will not work in conjunction with a Hammerschmidt crankset because the transmission that is produced undercuts Rohloffs permitted primary transmission ratio...
> 
> The idea of additionally mounting the Hammerschmidt with the SPEEDHUB is also fairly pointless. The result will be a combination of gear ratio "doubles" as with a typical derailleur gear system....


Actually, the Hammerschmidt & SpeedDrive are fine with the Rohloff, since it is a step-up drive (effectively making the front chainring larger). The MountainSpeed on the other hand will undercut the Rohloff's "recommended" ratio, which was what I was trying to point out above.

Adding a HammerSchmidt to a Rohloff is "pointless" only if you already have enough gear range, but if you want more range (like MABman, or some recumbent riders I know) it's a very good way to get extra range (HammerSchmidt adds 4 gears, MountainSpeed adds ~8 gears).



scuppy said:


> Well I'm running 80W gear oil in my Rolhoff and produce more torque than I'm supposed to. Hang on there's someone at the door...


... someone should have been knocking on my door years ago... they must have missed me because I kept moving...


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## estutjaweh (Jan 3, 2008)

That is not quite correct. The Speeddrive is fine because it uses a large chainring and increases the ratio produced when shifted out of the 1:1 ratio. 

The hammerschidt however is a different system. This undercuts the Speedhubs permitted gear ratio when it is shifted into its 1:1 ratio simply because the chainring that it utilises is too small and there is currently no plan to release the system with a larger chainring. If therefore you are only able to use one of the two gears provided..... what is the point!


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## itsdoable (Jan 6, 2004)

estutjaweh said:


> The hammerschidt however is a different system. This undercuts the Speedhubs permitted gear ratio when it is shifted into its 1:1 ratio simply because the chainring that it utilises is too small....


Ah yes, I keep forgetting there is no chainring option on the Hammerschmidt. My SpeedDrive has a 27t option, as well as standard 110 rings.


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## themanmonkey (Nov 1, 2005)

In the late-90s I used a Schlumpf Mountain Drive with a Sram and Nexus rear wheels. It didn't work all that well as extending the IG range, except when you though of them as kind of a multiple dingle-speed. Basically you had a set of gears for riding on the flats and a set of gears for riding in the hills. I put a bunch of miles on it until I had to give the demo Schlumpf back.


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## punchy (Sep 30, 2008)

Im a little dissappointed to hear the two are not compatible. As i have been mulling over the idea for a while now.

The way i see it, it can be done but voids the Rohloff warranty right ? 

Steve


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## corex (Sep 10, 2008)

Use a 13 teeth sprocket on the Rohloff. And it will work with in warranty.

Chainline is aprox. 3 mm wider as with a 15,16 or 17.


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## estutjaweh (Jan 3, 2008)

Please explain how you worked that out!


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## punchy (Sep 30, 2008)

+1 ^


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## corex (Sep 10, 2008)

I'm riding a trek fuel 8. In front a Q-ring 34 chainring . On the backside on the Rohloff a 13. Because of the pedal effects on the suspension. The 34 is nearly level with the main pivot of the rear suspension.
The smaller front chainring gives also more room for big obstacles.

The Q-ring is inside out mounted on the outside of the crank for good chain ailinement.
The chaintensioner is also placed more to the outside ( 3mm: see post before this one) with some steelrings.


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