Crowd ask: Classified Hub

[Michael Turek]

Hi all,

I’ve enjoyed the long threads of randonneurs sharing experiences on equipment.

This summer I thought 30/34 was sufficient for climbing so many 15% grades at Granite Anvil (also thought first day I could hang with fast guys 😮‍💨)

I’m looking for a wider range and came across classified with 1 / 0.7 planetary gear ratio.  This would give 1x42 front, 10/44 rear a range from .66 to 4.2.

Other than downside of cost (new wheel, hub) and a pound of weight…has anyone experienced issues? 

Looking forward to comments!

Mike 10173

[Jim Howell]

Hi Mike,

On my velomobile I run a Schlumpf Mountain Drive with a 70 tooth chainring up front and an 11 speed 11-46 standard derailleur cassette in the back. The mountain drive has a 1/0.4 ratio, so my 70 tooth front chainring is equivalent to a 28 tooth when in 'low'. Therefore, when in the lowest setting, I have the equivalent of a 28/46. I love it. Ample range to drag a 65 pound machine (with all the crap I carry) up the hills while allowing it to scream along on the flats. I've often thought if I built another upright I'd put a Schlumpf on the front, just to be rid of the derailleur mechanism and associated cabling, etc. Shifting is super easy, the tap of a heel. And you shift while not pedaling, so downshifting when stopped (like when you forget to downshift after a fast run and then get stuck at a red light) is possible, and although this sounds like it would be a pain to have to stop cranking to shift while moving and pedaling, it only requires a very brief pause.

Some people state that the planetary gear systems are not as efficient, or that they feel 'spongy' when pedaling. Intuitively I could see a loss of efficiency, since the drive system has a small amount of inherent friction, but I recall reading somewhere the losses were only a couple percent (i.e. a normal drive system might be 95% efficient and adding the planetary drive system reduces this to 93%). As for sponginess, any mechanical drive system requires some tolerances to allow smooth operation and reduce wear, and the planetary systems do have some play that might appear as sponginess when pedaling. I notice some sponginess in the velomobile when mashing on the pedals, but I think it is due as much to chain stretch as the planetary gear system (the velomobile has the equivalent of 3.25x the number of links of an upright bike, so lots more links to stretch and contract when pedaling). I do not find it overly annoying or impactful.

As for weight: yes, the MD is heavier, but the important way of thinking about this is net change in bike weight. On the velombile, all the standard derailleur hardware (shifter, cable, cable tube, derailleur, derailleur bracket) weighed around 1 kg. This was replaced by a 1.3 kg mountain drive so the net change was 300 grams. On an upright I think the net difference would be larger, probably closer to 500-600 grams, but not as large as the 1300 grams of the drive itself.

The Schlumpf system does require a supplemental mounting bracket to prevent the whole assembly from rotating. This bracket looks like the one on single speed coaster brake wheels, and mounts to the frame in a similar manner. I think this can be accommodated on a standard frame using a retrofit bracket, but this is something to keep in mind and check before committing. This bracket system is new and eliminates the need on older Schlumpf systems to machine a conical taper in the frame bottom bracket and then torquing the drive system to ridiculously high values, which was a deal breaker in the past since you could never revert back to a standard bottom bracket setup after the taper was put in.

There are two types of Schlumpf systems: the mountain drive, which steps down 40%, and the high speed drive, which steps up 165%. For the former you'd put a large chainring up front (likely a 50 or so for an upright), and for the latter you'd put a small chainring. I'd advocate for the mountain drive, since with a 50 tooth chainring you'd have the equivalent of a 20 tooth when in low. I also found that the high speed drive had quite a few gear combinations that were essentially identical, reducing the total number of gear combo's to something like 19 or 20 for an 11-speed cassette. My velomobile setup has no overlap, so basically provides 22 speeds. It might be a nit, but something to consider. The high speed drive also did not provide as wide of an overall range. I think the high speed drive is the one you were noting in your original post.

The Schlump systems have in the recent past been a bit hard to get, but they are now being produced by a new company and are more readily available. They are made in Europe and the number of US suppliers is limited, so service and maintenance might be an issue, so something to keep in mind. They are completely sealed, so the gear system itself is pretty well protected and thus should last a long time. And they are expensive, but oh, how I love mine.

Hope this helps- can't wait to hear from others!

Cheers,

Jim

[Ramsey Hanna]

If you want a lower gear ratio, I would just use a mtb groupset. you can put a 40t chainring and you’ll have a 52t cassette. Both sram and shimano have systems for it and I’ve fit them to my road bikes before,

Ramsey

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[Drew Carlson]

This is the limitation of a 1x system, IMO.  I'm a big fan of Shimano GRX 46x30 with an 11x42 rear cassette.  I have this on only one bike, but there are times on some long rides with very steep grades that I want gears that low.  This would be easier, cheaper, and less heavy than a planetary hub.  Hope you find something that works for you!

[Kent Beernink]

I also use GRX, but I have a 46x28 on the front with the 11x42 on the back. Works great on steeper hills. I swap the rear wheel to an 11x34 for most of my riding. 

Kent Beernink

On Nov 27, 2025, at 10:57 AM, Drew Carlson <w.drew....@gmail.com> wrote:

This is the limitation of a 1x system, IMO.  I'm a big fan of Shimano GRX 46x30 with an 11x42 rear cassette.  I have this on only one bike, but there are times on some long rides with very steep grades that I want gears that low.  This would be easier, cheaper, and less heavy than a planetary hub.  Hope you find something that works for you!

To view this discussion visit https://groups.google.com/d/msgid/randonneurs-usa/112cbc1c-9698-4e12-a9b9-58b85cbd6820n%40googlegroups.com.

[Andrew LaMarche]

I have two non-conventional bikes that I've used on rando rides

• Priority Apollo - Belt Equipped + Alfine 11
• Priority Gemini - Belt Equipped + Pinion C1.12i
  

In short, I really like both drivetrains. When cycling with others on conventional drivetrains, I can definitely feel the relative inefficiency of the internal gear drivetrain, but I also don't particularly care as long as the low level of maintenance gets me out riding more frequently. Overall, I prefer the pinion-equipped bike given the rugged type of riding I typically do, which would be incompatible with the Schlumpf. But with 600% of range, I haven't felt the need for a 2x.

If I did flatter rides, I would probably just use the Alfine 11 bike for the bulk of my rando rides. Unfortunately, its gearing range is too shallow for my level of fitness and the rides I do, and equipping it with lower gearing could exceed its torque ratings. I rode the Rangeley 600 perm with this bike (ride report if you care), and the gearing truly hurt in the White Mountains. I haven't run into the reliability issues folks have had with the early iterations of the Alfine 11, but I think you would want to go with Rohloff for the reliability, gear ratio, and torque ratings if you're set on a gear-hub rather than a gearbox.

Happy to lend more input if needed. 

-Andrew