Bicycle Mechanics - Mountain Drive / Speed Drive

I'm curious if anyone has any experience with this product? It's a planetary gear system that installs inside the bottom bracket that either increases (speed drive) or decreases (mountain drive) the normal range of a bike with a internally geared rear hub (I suppose it could also be used with a rear derailleur). It looks like a good product, but it's pricey, and appears to require a frame mod to the bottom bracket, which means you may not be able to go back to the original configuration...

http://www.schlumpf.ch/md_engl.htm

Hey Merton,

You were looking for a giant chain ring. Here's your answer. Get a 53 and this puppy (Speed drive) and you can bust a tendon or two.

I'm curious if anyone has any experience with this product? It's a planetary gear system that installs inside the bottom bracket that either increases (speed drive) or decreases (mountain drive) the normal range of a bike with a internally geared rear hub (I suppose it could also be used with a rear derailleur). It looks like a good product, but it's pricey, and appears to require a frame mod to the bottom bracket, which means you may not be able to go back to the original configuration...

http://www.schlumpf.ch/md_engl.htm

As I understand, you can either cut a bevel inside the BB (i think they will sell you
the cutting tool), or use the torque lever installation:

Quoting from the installation guide: "The torque lever is fitted to the rear chainstay with a clamp (included in the shipment). If using the torque lever, you don't have to modify the bottom bracket at all."

regards,
-j

The last time I saw a planetary drive on the crankset was Charlie Harding's 90-speed bike (5 cogs * 3 chainrings * 3-speed hub * 2-speed crank).

> which means you may not be able to go back to the original configuration...

Only the Mountain Drive comes with the torque arm, you have to bevel the BB for the Speed Drive. As long as your BB shell is ~>= 41 mm OD, you shouldn't have a problem putting a standard BB back in if the tapering was done correctly (39-39.5mm OD). If you have a thinish BB shell, it might be a good idea to make a tapered spacer to fill the tapered area if you put a standard BB back on later.

The Schlumps can be the greatest thing since sliced bread, if you need them, but it's not clear from you original query why you think you might. A properly adjusted front derailleur is more efficient, but Schlumpfs really aren't bad. There are probably a lot of people riding around on worn out and misadjusted derailleur equipped bikes that are wasting more energy. Here are some miscellaneous ramblings, and things to be careful of:

A Schlumpf can be shifted while standing still (#1 benefit in my book).

The shift knobs really don't fall off or wreck the drive IF installed and torqued correctly.

The easy shift EX-Shift arms make shifting while pedaling a LOT esier, but are only available for 170mm crank arms.

Although a little noisy at first (particulary in the indirect ratio), they quite down significantly in a few hundred miles.

The tendency for the pedals to want to turn when freewheeling or pushing the bike also gets better with time.

You might need to order the +10mm BB spindle version to fit some chainlines properly.

Not all 3rd party square taper spiderless cranks will "fit", but some of the ones that don't can be machined to work. You would be better off getting "approved" cranks from Schlumpf if if one of their size offerings will work for you.

Florian Schlumpf is a cool guy who is working on a two speed hub for Unicycles.

John

if you need them, but it's not clear from you original query why you think you might. A properly adjusted front derailleur is more efficient, but Schlumpfs really aren't bad.

I would match these up the way they suggest; with an internal rear hub (in my case a Shimano Nexus-7) Probably I would use the mountain drive to get some more low climbing gears.

I would match these up the way they suggest; with an internal rear hub (in my case a Shimano Nexus-7) Probably I would use the mountain drive to get some more low climbing gears.

randya - Therefore, some may point out that the Mountain Drive version would be operating in its least efficient (indirect) mode in the lower gear range you desire. I say horse puckey, it will give you what you want (if the rear hub can take the extra torque).

Since you're talking Mountain Drive, you do get a choice on mounting options, and for what it's worth, I've never had or heard of a case of anyone having a problem with a properly installed torque arm mount version, but there can be fit restrictions that might prevent using that one on some bikes. I have heard tales however of exeptionally strong riders with long cranks being able to spin the taper mount versions on trikes with ridiculously low gear ratios (like 10 gear inches or so), but I've never done it on anything of mine and have always wondered whether the "slippers" were installed properly (100 ft lb is a LOT of mounting torque, and they should be retorqued a couple of times while things are settling in during the first few hundred miles of use). With a "Toolkit #1", I don't know how anyone can be sure of the torque, and although "Toolkit #2" does let you use a torque wrench, it's a pain to have to pull the left crank to use it. Get both if you go for it. I don't think it twould be a good idea on planning to use the taper mount version if the OD of your present BB shell is less than ~40mm, you definitely don't want to skimp on cone seating area with the Mountain version. I couldn't find anywhere to "rent" a Schlumpf taper reamer in the US, so unless you're near one of the few LBSes that have one, you might be stuck with having to buy one or come up with an alternative if you're going to go with the taper version.

Florian Schlumpf can sometimes come up with custom or mix-and-match mounting bits to help fit one of his drives to a a BB configuration that doesn't quite match the published listings of slam dunks and no-ways.

John

I would match these up the way they suggest; with an internal rear hub (in my case a Shimano Nexus-7) Probably I would use the mountain drive to get some more low climbing gears.


I know im a bit late, but ive got a mountain drive equiped on my trike. Its a lovely piece of machinery. Ive got it hooked up to a SRAM Dual-Drive rear hub(3 internal, 8 external) for a total gear range of 9.1 to 122 inches(if I done my maths right). Ive done over 12000k on it without any significant problems. Ive purchased it strictly for the reason you mentioned above, nice low climbing gears for a heavily laden touring trike.