Schlumpf vs Di2

As I spool this project back up, there is just one question nagging me:  Is Schlumpf the right choice?  Reality has modified many of my initial aspirations, I think it’s worth reconsidering a Di2 front derailleur instead.

I’ll admit, the primary motivation for this smack-down is my growing uneasiness with internally geared hubs.  If not for that, Schlumpf would be the clear winner:  Improved chain line; no front shifter; no clunky front derailleur; a single, small front chain ring, wide gearing.  But my track record with internal gearing is pretty grim.

And some of Shlumpf’s advantage is eliminated in a world with Ultegra Di2 for both front and rear.  Without a single cog in the rear (Alfine), the Schlumpf’s contribution to a clean drive line is less significant.  Di2’s ability to coordinate shifting between the front and rear derailleurs—sequential shifting, or synchronized shifting in Shimano’s parlance—allows one-handed shifting.  This means the front shifter is eliminated, one of the biggest advantages that Schlumpf brings to the table.  While a front Di2 derailleur would require an extra e-tube cable running to it, it would be straightforward and clean to add it to my current setup.

But wait—synchronized shifting is a feature of Shimano’s mountain bike group, XTR Di2.  Does Ultegra offer it?  The surprising and disappointing answer is no.  I’ll leave it to this article to explain why.  So now I’m looking at wiring an extra shifter for the front derailleur.  It’s an e-tube cable, so meets my requirement for a sealed, weather-proof system, but still not ideal. 

Further, I’d be giving up the incredibly wide gear range offered by Schlumpf High Speed Drive (HSD).  But I may be OK with that.  I’ve already begun to lean toward the Speed Drive (SD) instead of HSD if I stick with Schlumpf.  While it offers wide gear range, the massive jump to overdrive is pretty unwieldy, requiring seven down-shifts of the rear derailleur if all you want is the next highest gear.  And of course the reverse is true when shifting down.  This might be OK if I could run the Schlumpf most of the time in one gear or the other, but the numbers don’t really line up this way.  This also means one of the big advantages of internal gears—the ability to shift when not pedaling—is all but lost because the shift is probably useless without a corresponding shift in the rear, which you can’t do without pedaling.


Ultegra and Schlumpf High Speed Drive

And then there are the wasted gears.  I like to go fast, but am perfectly content relying on gravity for the big downhills.  And this is not the machine on which I’ll be breaking the land speed record for human-powered travel.  I don’t need to be cranking at 85.71 MPH, or even the 40+ MPH I commonly achieve on a downhill.  My highest gear should correspond to the fastest speed I can regularly sustain while cruising.  Maybe I’m a wimp, but I don’t typically cruise at the 32MPH afforded by 119 gear inches (GI).  100 gear inches and 27 MPH should be more than enough, which means two wasted gears on the top end.  On the bottom end, gearing in the 16 GI range was arguably a necessity when loaded with 200 pounds of gear and a nine-year-old.  But I don’t anticipate doing that again—Zoe can do her own cycling now.  Since that tour I’ve rarely used, and never actually needed, my smallest front chain ring.  I can tackle any hill in the 20 GI range, which means about two more gears wasted down there.  And if I’m wrong, the fix is as easy as swapping in a smaller chain ring, assuming I’m running the Schlumpf.  On a self-supported tour, I need a high cruising speed even less than on a recreational ride near home.  The following graph shows how things look with the HD.  98.9 GI corresponds to about 26.5 MPH when cranking at 90 RPM.


Ultegra and Schlumpf Speed Drive



Ultegra Front and Rear

Of course there is a third option that I discuss here,  XTR Di2.  This technology is still in its first iteration, in Shimano’s most expensive mountain component group.  It’s really expensive and would mean swapping out the Ultegra derailleur and (maybe) rear hub I’ve already invested in.  I think that ship has sailed for this project.  With Schlumpf Speed Drive, XTR means maybe two wasted gears per my previous rationale, but pretty reasonable.  XTR in front and rear is a non-starter with the widest cranksets currently offered by Shimano, either 2×11 or 3×11, because the gearing is shifted way too low.  So an XTR front derailleur doesn’t appear to be a viable way to eliminate the Schlumpf.


XTR and Schlumpf Speed Drive


  Schlumpf HD or HSD Ultegra Front and Back Schlumpf SD + XTR Di2
Crankset $800 $250 (?) $800 (Schlumpf)
Rear Derailleur     $650
Front Derailleur   $225  
Shifter   $100 (?)  
Rear Cassette     $220
Total $800 $575 $1,670

Incremental Cost of Gearing Options

Which will it be?  A Di2 Deore or XT rear derailleur looks like a great future option if I stick with Schlumpf Speed Drive in the front, after the Di2 technology trickles down from XTR, but it’s not an option now.  An Ultegra front derailleur is tempting, but the (slightly) reduced range, the requirement of a front shifter, and the inherent scuzziness of a front derailleur make this option less appealing.  I’ll go with the the Speed Drive based on the earlier discussion, and because it leaves open the possibility of swapping to a mountain Di2 rear derailleur in the future.  I’ll consider the Ultegra option a backup if my final foray into internal gears winds up a bust like all the others.  

1 thought on “Schlumpf vs Di2

  1. mkzig

    While I am generally pleased with my Schlumph High Speed Drive, I agree that the Di2 front is worth a look. Having a single chain line (at least in front) is nice and the simplicity of a mechanical button leaves fewer things to go wrong (hopefully). On the other hand, if the front derailleur is as functional and robust as the rear Di2, then the advantage of a wider gear range would be attractive.



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