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Shamisen Appreciator
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Discussion Starter · #1 ·
I've been searching through the forums for a while, and lurking on every speedhub thread I can find but I still have a question...

The Rohloff USA site recommends that a gear smaller than 2.4 times the rear cog is used. Why?

because the torque to the internal gearing would go beyond design parameters?

because the gear spread is such that anything less than a 2.4:1 ratio would result in unuseable low gears?

other reasons?

I'd like to use the smallest chainring/cog combination I can get away with (for clearance reasons) while still maintaining a sufficient level of chain wrap in the back.

Sean
 

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smudge said:
I've been searching through the forums for a while, and lurking on every speedhub thread I can find but I still have a question...

The Rohloff USA site recommends that a gear smaller than 2.4 times the rear cog is used. Why?

because the torque to the internal gearing would go beyond design parameters?

because the gear spread is such that anything less than a 2.4:1 ratio would result in unuseable low gears?

other reasons?

I'd like to use the smallest chainring/cog combination I can get away with (for clearance reasons) while still maintaining a sufficient level of chain wrap in the back.

Sean
#1 - torque "could" fall outside of recommended operating range.

That limit is probably conservative based on the maximum amout of torque a cyclist could apply. Unless you are a world class athelete with tremendous power, you should be able to get away with a smaller ratio, within reason of course. If you really want to go as small as possible then you'll just have to weight the risks based on how you ride.
 

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Shamisen Appreciator
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Discussion Starter · #3 ·
I'm no world class athelete but I am relatively big (190lb) and would consider myself to be strong but not godzilla like.

I'd love to drop down to a 29 or 30t chainring just to get a little added clearance, but even using what I use now, (32t) I'd have to use a 13t cog in the back. That doesn't give much chain wrap and tends to be a little rough on the cog/chain.
 

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Maximum Speedhub input torque is listed by Rohloff at 100Nm, which of course can be multiplied by 2.4 or whatever gear ratio you use to figure out what acceptable force can be applied to a pedal stroke.

Additionally, with a 42x16 gear combination, a force equal to 98% of the crank force is applied away from (pulling force) the disc brake tabs in an OEM2/Speedbone setup, so the potential of a frame limitation exists. This percentage should increase past 100% with lower gear ratios. This is most likely the reason for their Speedbone liability waiver. This force decreases through the gear range and eventually changes to a pressing force in the last few gears.

The good news it that:

* Rohloff USA told me of a recumbent rider who's puttering along in a 32x13 (2.46:1) gear, with no problems.
* The same 38x16 (2.375:1) min ratio that applies to you and I also applies to tandem riders, which have the potential of producing double the output.
* I think it's a safe assumption that in super low gears, we're not cranking along in a "max torque" mode.
* If you do happen to exceed the hub's design limits, what *should* fail are the 9 nylon "plugs" that join the internals to the shell (note the three white plugs along the exposed portion of the hub in the attached photo, just inside the non-driveside flange. This requires removal of the hub cap and a new seal to repair, but the good news is it it both inexpensive and quick.

I'm running a 34x15 (2.27:1) on my wife's Mount Vision. She's no power rider, so she is probably a bad example, but no trouble on her hub. I've think I've used 40x17 (2.35:1) on and 38x15 (2.53:1) without trouble.

I've also attached a matrix showing what derailleur equivalents various chainring & cog combinations will get you.



 

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smudge said:
I'm no world class athelete but I am relatively big (190lb) and would consider myself to be strong but not godzilla like.

I'd love to drop down to a 29 or 30t chainring just to get a little added clearance, but even using what I use now, (32t) I'd have to use a 13t cog in the back. That doesn't give much chain wrap and tends to be a little rough on the cog/chain.
Just saw this post. As you can see from the matrix, 30 or 32 x 13 is a reasonable gear ratio, but in addition to the chain wrap & wear issue, you also have a wider chainline to address (unique to the 13T cog), and the 13T cog is not reversible like the others, so the already reduced lifespan is now cut in half.
 

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rebuild/service kit?

Looking at the inside "big" pic of the hub, is there a rebuild kit for most common parts which would under normal use wear out? I've noticed a little "chunky" noise coming from my speedhub, abot 3 years of xc use with regular oil cleaning/oil changes, thought about "opening" the hub wide open to fully "clean" the inside out. ever disectted one yet?

Vern
 

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No kits I'm aware of. Thomas at Rohloff continues to insist they haven't seen a "worn out" hub yet, but I think at least the outer seals must need occassional replacement. If you can get that guy on the phone, he'll be pretty straight up with you and I'm sure give you a list of what to inspect. I've seen him crack these things open and I have to admit, I'm a little apprehensive about prying the hub cap off without some explicit instructions (there's got to be something better than a flat bladed screwdriver).

I wonder if, once opened, it could just be run in a kerosene bath for a few minutes for a comprehensive flushing, then rinsed with the normal gooey rinse oil before being repacked.

Here's a blurb from their German website:


23.04.2004 You see that you do not see anything - ---

news
we, too! This SPEEDHUB 500/14 has been driven nearly 90000km and was returned from a customer to an inspection and closer examination. We've found out the gear box is still functioning perfectly well and it will surely do many more kilometres. The 100000km line moves closer ...

[TR][TD]
[/TD][/TR]
 

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thanx..

Thanx for the info....I've replaced the outer "blue" seals on my hub at the 2 year point, started to leak a little to much for me, I'm due for a new cog on mine, lots of mileage, In the pic of the cut away hub, There is a spring under the driver just past the larger bearing, wonder if these get a little weak over time? As for "prying" open with a screwdriver, Don't like the sound of that, rather "tap" the axle end with a brass mallet to free things up..Wouldn't kerosene be a little hard on the inner seals and carbon parts? Was thinking more of using compressed air to clean out the gearbox internals.

VernDog
 

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I don't know how harsh and abusive the kerosene might be, and admittedly I'm not going to be the one to volunteer my hub to find out. But there are so many nooks and crannies for dirt or metal shaving to hide in that I imagine neither air nor the oil-based rinse can properly get it all out. But I'm probably looking for a solution for a problem that doesn't exist.

How's that seal change of yours holding up?
 

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Going below a 2.4 ratio means you "could" exceed the load spec on the hub, and if damage occurs, it may not be warrentteed. However, off the record, several people have experimented with lower ratios without issues (being inteligent about it ofcourse and not putting a 250 lb masher on a 32:20 and try to climb the steepest singletrack...) And as Speed�b says, there are internal plastic coupling that are designed to fail first.

Keep in mind you can run a 38:16, and BlackSpire makes a bashgaurd for that size ring, which is not much bigger than most middle ring bash gaurds. I've been running that in the rock gardens and don't really notice clearance issues compared to my 32t+bashgaurd crank. I would like to have lower gears sometimes, but it's not really necessary, the lowest gear with the above ratio is equivalent to a 22:33, pretty close to the 22:34 lowest available with 9-speed (although you can get 20:34 if you use a compact chainring).

Dismantling - been there done that...

The entire innards of the hub comes out in one shot, still attached to the hub cap, so dismantling is not a big issue. However, only the plastic torque transfer rods come off, the rest remains as a factory servicable only unit. However, the manual states that reassembly require you to replace the paper gasket on the hub cap ([email protected] says you can re-use the original if you are careful when disassembling). The only reason I can think of disassembling it is to 1) replace the seals, or 2) replace the torque transfer rods.

Here is my mark-1 internal guts from 4 years ago...


Kerosene is "probably" OK for cleaning the hub as it is the suggested additive for cold weather use - new (not yet fully broken in) hubs will mis-shift at low temps (~ -10C/14F) due to oil viscosity. Thomas recomends adding a "small" amount of Kerosene to thin the oil. I've been doing this for the last few winters with good results. Oil seepage does increase though. However, I believe regular oil changes and rincing is adequate, I would not bother opening the hub just to clean it.

Cheers,

Tom
 

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if you're concerned about the corrosive effect of kerosene (as I would be, with such an investment) then just use a citrus based degreaser like simple green or orange peelz. These are completely water soluble so you can rinse it out, dry it with compressed air and then re-lube. I might have to get one of these things for my XC rig when I get back. Does the speedhub come supplied with a shifter? Is this easily replaceable?

- Joel
 

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Simple Green scares the snot out of me -- far too caustic from what I've seen of its effect on chains left to soak in it for a few hours, definitely caustic towards aluminum and other alloys.

The hub comes with somewhat clumsy-looking twist shifter that, despite its angular looks, does the job nicely.

 

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tomacropod said:
if you're concerned about the corrosive effect of kerosene (as I would be, with such an investment) then just use a citrus based degreaser like simple green or orange peelz. These are completely water soluble so you can rinse it out, dry it with compressed air and then re-lube. I might have to get one of these things for my XC rig when I get back. Does the speedhub come supplied with a shifter? Is this easily replaceable?

- Joel
I would NOT use a citrus degreaser, many acids & bases that are used as a degreaser are completely water soluable, and not at all friendly to the aluminium or carbon parts. I would use what Rohloff recomends, which is thier rince oil, and kerosene.

Shifter comes with the unit, but is propriotary. Replacements available from Rohloff only, although I've seen a DIY one made from oiled hardwood.

Cheers,

Tom
 

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itsdoable said:
I would NOT use a citrus degreaser, many acids & bases that are used as a degreaser are completely water soluable, and not at all friendly to the aluminium or carbon parts. I would use what Rohloff recomends, which is thier rince oil, and kerosene.

Shifter comes with the unit, but is propriotary. Replacements available from Rohloff only, although I've seen a DIY one made from oiled hardwood.

Cheers,

Tom
And why, oh why, doesn't Rohloff make a drop-bar shifter??? The speed hub is the best system I've seen for long distance touring bikes... You can even use a rear derailleur or the Rohloff tensioner and run two chainrings at 1/2 the gear gap, about 3 teeth... 28 gears, no duplicates, and even 6.8% jumps from 20 to 110 inches!! Gear-geek nirvana!!

--Shannon
 

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tube_ee said:
And why, oh why, doesn't Rohloff make a drop-bar shifter??? The speed hub is the best system I've seen for long distance touring bikes... You can even use a rear derailleur or the Rohloff tensioner and run two chainrings at 1/2 the gear gap, about 3 teeth... 28 gears, no duplicates, and even 6.8% jumps from 20 to 110 inches!! Gear-geek nirvana!!

--Shannon
...20 to 110 gear inches... hummmm - forget the chain tensioner and put a Schlumpf high-speed drive crank...

The lack of drop bar shifter is where this DIY version came from:

The wood part splits in 2 so you can place it near the stem on the drop bar.

Cheers,

Tom
 

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tube_ee said:
And why, oh why, doesn't Rohloff make a drop-bar shifter??? The speed hub is the best system I've seen for long distance touring bikes... You can even use a rear derailleur or the Rohloff tensioner and run two chainrings at 1/2 the gear gap, about 3 teeth... 28 gears, no duplicates, and even 6.8% jumps from 20 to 110 inches!! Gear-geek nirvana!!

--Shannon
When I was putting my bike together, I ended up leaving the triple chain ring and front derailleur on for a little while. It served no practical purpose but I did get some amusement from pointing out my 42 speed bike. Geeky fun at it's best!
 

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seals real..

Speedüb Nate said:
I don't know how harsh and abusive the kerosene might be, and admittedly I'm not going to be the one to volunteer my hub to find out. But there are so many nooks and crannies for dirt or metal shaving to hide in that I imagine neither air nor the oil-based rinse can properly get it all out. But I'm probably looking for a solution for a problem that doesn't exist.

How's that seal change of yours holding up?
The seals, new improved have been working really good, no leaks, also replaced the axle plate retaining bolts with new bolts with sealant/applied and new gaskets between the axle plate and cable box. All good. I don't lay my bike down on either side so the oil doesn't have a chance to build up near either seal. read the posts about the simple green, no way is that stuff going to be on my bike, That stuff will lift the chrome plating right of aluminium let alone what it could do to seals, etc.

Vern
 

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Vernon VernDog said:
The seals, new improved have been working really good, no leaks,
Are these the most recent "single external seals" that were to do away with the need for the pair of internal seals?

I'd like to experiment. I only ever had very light seepage around the seals, which leaves a film that collects a light coating of dust, but have never had a problem with drips.
 

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seals...

Speedüb Nate said:
Are these the most recent "single external seals" that were to do away with the need for the pair of internal seals?

I'd like to experiment. I only ever had very light seepage around the seals, which leaves a film that collects a light coating of dust, but have never had a problem with drips.
The seals look like the same as the original kind that came with the hub, I did notice a bit more "drag" between the cog and hub when coasting, better tolerances I guess. My hubs serial # is 11765 which I but new in 2001. Also, I replaced the seals between the axle plate and cable box, and If I remember, a seal between the cable box and hub (thin paper type?) been a while as I had no leaks since!
The new hubs have done away with a internal seal (bearing seal?)
I built up a new hub with the disc option for my fr/dh bike, noticed a little difference in the axle plate/cable box bolting, a small bolt holds on the cable box when the axle plate is removed for rotor install/changes, shifting indexing is "lighter". Maybe this hub has the external seals only, just hope it doesn't decide to leak on the rotor side, oil and disc brakes, not a good combonation...

Vern
 

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Yeah, the new seals are supposedly outside the bearing only. The removal of the inner seals means the main bearings get the full oil bath treatment.

Not familiar with the paper seals on the shifter box you're referring to -- none of mine have it but they're older s/n's than yours.
 
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