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Has anyone retrofitted a schlumpf on their strida?

Advice from experienced owners on maintenance and repairs, riding skills and anything else.

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Re: Has anyone retrofitted a schlumpf on their strida?

Postby fwd-bwd on Sat Jun 05, 2010 8:11 pm

For anyone who's intrigued, here's the cost breakdown:

Speed Drive Kit, including silver crank arms CHF 689
Black crank arms (optional) CHF 10
Strida Parts (EBB, sprocket, and belt) CHF 100
Easy-shift kick plates (optional, silver or black) CHF 45
Strida installation and maintenance toolset CHF 32

Schlumpf offers 4% rebate for bank transfer payments cleared within 10 days after purchase. The deal is probably only available to continental Europe though. Anyway, people who are interested should contact Jolanda <>. It's a small company therefore it may take a few days before someone replies your inquiries. So be patient.

Re: Has anyone retrofitted a schlumpf on their strida?

Postby smitt53 on Mon Jun 14, 2010 8:52 pm

I fitted both the Schlumpf drive and 18 inch wheels to my Strida 5 last weekend. Here's a picture of the new setup:

The transaction with Schlumpf was very smooth. They don’t have secure ordering capability on their web site, so I phoned them up and provided my credit card number verbally. The package took less than a week to travel from Switzerland to the west coast of the USA.

Installation was very easy, no drama at all. Everything went together as intended and the entire process took less than one hour. Belt alignment is perfect and everything runs very smoothly.
I live in Oakland, California and the weather the past week has been perfect, so I got a few miles in. The combination of the slightly larger wheel/tire combination, lower rolling resistance tires and availability of a higher gear makes the bike much more usable for longer rides. I find myself using the lower gear most of the time, but for nice long flat stretches with little or no incline or headwind it is nice to have that taller gear. The tall gear is somewhat taller than I would like, I have to be going pretty fast before it works for me. It probably would have been more to my liking with the 16 inch wheels, but I did both mods at the same time…

It takes some practice to shift quickly. First you have to position the pedal, which I don’t find particularly instinctive – I have to think about it every time. Then you have to use an unusual movement with your heel, pushing sideways on the crank pin. This takes time, I’m not sure I will ever get to the point where I am “speed shifting”. There is a soft clunk as the gear engages, usually. Sometimes the gear engages with little or no noise. Because of this it is usually, but not always, obvious that the new gear is engaged.

Internal friction of the 2-speed drive is quite impressive. In fact, it is hard to tell subjectively which gear is direct-drive (it’s the low gear). That works for me, since I am spending most of my time in low gear. Once I build up some speed and upshift I can’t really notice any additional drag. Everything runs along quite smoothly.

Overall I am very happy with the Schlumpf 2-speed drive. It is a beautiful piece of engineering and machining and improves the appearance of the bike. The drive itself is remarkably small and compact. I need to practice my shifting, faster shifts would improve things considerably.
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Re: Has anyone retrofitted a schlumpf on their strida?

Postby RichardCoffey on Tue Jun 15, 2010 12:28 am


Thanks very much for sharing the information about your Schlumpf Speed-Drive upgrade. It sounds like a winner. I'm especially delighted to hear that the ordering and shipping process to the USA went well.

It is also interesting to hear that you swapped your stock 16 inch wheels for 18 inch wheels at the same time. If switching between the two sizes is a painless process too, then you have even more flexibility for dialing in a good setup for your needs.

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Re: Has anyone retrofitted a schlumpf on their strida?

Postby Ed on Tue Jun 15, 2010 1:58 pm

seems like with the 18 inch wheels you get the original 52 gear inches in the low gear and the high gear is almost pushing probably 80 gear inches. That thing is going to go like stink on a downhill. Fastest I went on a strida is 40km/h downhill and it was pretty stable as long as you relax and not have some death grip on it. else you got a really nice setup. Did you carry that wheel stand with you wherever you go in case of photo ops? :lol:

Re: Has anyone retrofitted a schlumpf on their strida?

Postby Guest on Tue Jun 15, 2010 2:17 pm

Thanks for sharing the review.
I guess the Swiss Shlumpf is the 'Rolls-Royce' of the gears: as a cheapskate, I'd love to compare with the ATS, licenced version of the gear. Does anyone have any news that Ming are selling this as an upgrade / accessory yet ?

Re: Has anyone retrofitted a schlumpf on their strida?

Postby fwd-bwd on Tue Jun 15, 2010 2:58 pm

@smitt53: Thank you very much for sharing. Regarding speedy shifting, you may want to consider adding Schlumpf's "EZ-shift kick plates" to your crank arms. I heard it'd make shifting easier.

@Guest: I contacted a few Strida distributors in different regions and none of them carried the kit. It seems that at this moment the only way to obtain it is ordering directly from Schlumpf.

Re: Has anyone retrofitted a schlumpf on their strida?

Postby RichardCoffey on Tue Jun 15, 2010 3:02 pm

I am interested in the ATS Speed-Drive too, so I emailed them last month. Here is the first response:

"Because we only sale the ATS speed drive. The Strida need not only ATS but also the adapter for ATS parts. Therefore I have to check w/Strida company tomorrow.
I'll inform U the result later. Pls kindly wait."

And the second:

"Pls surf the website http://WWW.STRIDA.COM and leave a message or send a e-mail , Strida will endeavor to get back to you as soon."

I followed ATS's suggestion, but have not received a response from Strida.

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Re: Has anyone retrofitted a schlumpf on their strida?

Postby hydractiva on Wed Jun 16, 2010 6:41 am

Hi all.

The problem with the speed drive is that its ratio is not accurate for a single-gear bike.
The speeddrive is designed for adding versatility to a multi-gear bike.
So, in multigear bikes, the speed drive ratio works good because multiply the options you can choose for two. (if you had a bike with 5 gear, with the speeddrive you get 10). You allways can get the right ratio between 10 gears.
But for a single geared bike like the Strida, the speeddrive is only a "less-bad" solution. The jump between the low and the high gear is too big for a fine use.
When 16 wheels, you get a very very low first gear you never can use in flat ground. The second gear is the same that the original strida.
When 18 wheels, you get a first gear "almost" the original Strida ratio (a little bit lower), but the secong gear is too high, and you cannot use it if the wind blow a little bit against you or if the ground is not totally flat. Even with flat ground, the feeling is that you must make a big effort.

Now, my veredict.

Not a accurate design for the Strida.
Very expensive.
Would I buy it again?: YES :shock:
Why? Because it is better than nothing.

A last advice:
After 200 km. the effort for pedaling is decreasing a lot. I think the mechanism comes very tight from factory and It needs a little of use for a right work.
At the begining, pedaling in the high gear (with 18" wheels) was a pain. Currently is very much better.



Re: Has anyone retrofitted a schlumpf on their strida?

Postby hydractiva on Wed Jun 16, 2010 6:47 am

And an added advantage for the SD.

You can secure your Strida easyly if you put your chain-lock crossing the speeddrive plate and the bottom alloy welded triangle.

This is the most safety method for locking a Strida, if you must leave it alone.


Re: Has anyone retrofitted a schlumpf on their strida?

Postby Blackstridaaustria on Wed Jun 16, 2010 6:07 pm

@RichardCoffey: Thanks for ATS research and your friendly words.
On Spring 10 I asked Strida europe:
"The Taiwanese 2-speed gear of the Strida MAS is said to be very unreliable. Do you know more about that?"
"The MAS Schlumpf cannot be ordered as a spare part."
----- ? ------

@smitt53: Thank you very much for the pics, will there be more?
The Schwalbe Kojak tires of my 18" Strida, inflated at 8,0 bar, seem to lose air relatively fast (about 0,3 per day).
Did you make this experience as well?

@hydractiva: Fully agreeing to your verdict, I am sorry to say that I have trouble with your gearing description.
Please do not take this personally.

@All of you
My first impression after riding a few kilometers on the 16" Schlumpf Strida: at this moment I realized that I had not been biking for decades before I bought my Stridas in Spring 10:
The lower gear feels much too low for me and the higher one awfully high.
The smooth original 100:30 gear is suitable for a completely untrained stork leg but not the higher gear of the Schlumpf.
It's true, with the higher Schlumpf gear you can go much faster ... if you can.

But things are getting better every day...

There are no "hills" in the area I usually ride, but a few "drive-ups" or "raisings" hardly managable with the 16" original gear are nearly not to be managed with the 18" Strida. The lower Schlumpf gear lets me climb up these places without any problem, slowly of course. Acceleration in the lower gear is certainly much better than the original on flat road. After 2 or 3 rounds of the pedals it is advisable to switch to the higher gear, which brings me to shifting:
As smitt53 said, you will need practice first. But in my case shifting became automatic after 40 or 50 kilometers, meanwhile I shift almost intuitively and frequently. Always wearing high shoes, I kick the shifting button with the heel or ankle - the Strida aluminium pedals are a bit more slippery than the original black ones and support the little sideways movement of the shoes better.
Also shifting without interrupting the movement of the cranks is possible, it is just a question of the right moment (and really cool!).
With increasing practice I am on the way to handle the higher gear, my top speed on Schlumpf 16" might be around 22 km/h at the moment, and it feels the same as top speed on 18" with original gear, but at lower cadence.
By now I have ridden about 80 km with the Schlumpf 16" and about half this distance on the 18" Strida for comparison.

For better understanding of the gear mystery I did some research on the web, then I took a ruler and used these online gear calculators:

The tires:
size; name; description; diameter (measured), circumference (arithmetical); circumference (measured)

16"; Kenda Kwest; 16 x 1,50 (40-305); 38,5 cm; 120,95 cm; 121,2 cm
18"; Schwalbe Kojak; 18 x 1,25 (32-355); 42,1 cm; 132,26 cm; 132,6 cm

Based on the two measured diameters of the wheels, the gear inches were calculated, and here are the results:
the first values are calculated with wisil, the values in brackets are from the soulbike calculator.

16" with original gear: 50 (50,4) Schlumpf low: 40 (40,4) Schlumpf high: 66 (66,7)
18" with original gear: 55 (55,3) Schlumpf low: 44 (44,2) Schlumpf high: 72 (72,9)

From my subjective feeling and corresponding to the results I have to say that the higher Schlumpf gear with Kenda 16" tires is certainly not the same as the original, as hydractiva mentioned, maybe her/his gear calculations are based on different tire sizes?
Anyway, I'll have to train a huge load before changing the wheels of my Stridas against each other :mrgreen:

Here is another interesting thread about sport duos: ... mpression/

Did you know that Strida Europe offers the MAS again, "available third week of June"?
Update 06.07.10: "available last week of july"
Update 06.08.10: "available last week of august"

Warmest regards
Last edited by Blackstridaaustria on Fri Aug 06, 2010 8:25 am, edited 3 times in total.

"Who knows nothing, must believe all." *

[* line from "Aphorismen"; Marie von Ebner-Eschenbach, Austrian poet, 1893]
[* book title; Werner Gruber, Austrian physicist, 2010]
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Re: Has anyone retrofitted a schlumpf on their strida?

Postby Guest on Thu Jun 17, 2010 3:04 pm

Hydra's descriptions of 16" gear inches are inaccurate, at least according to the official specs. Check out the link shared by Blackstridaaustria and also

Re: Has anyone retrofitted a schlumpf on their strida?

Postby hydractiva. on Thu Jun 17, 2010 9:17 pm

Sorry for the mistake.

The high gear with 16" is higher than the orginal Strida one.



Re: Has anyone retrofitted a schlumpf on their strida?

Postby Amuro Lee on Sun Aug 15, 2010 12:09 pm

fwd-bwd wrote:

The official price tag is 519 euros! Maybe it's to justify the cost or to deter people from buying ATS Speed Drive, Schlumpf made this statement:

"Please notice: the internal parts were modified in order to correspond with the higher proload of the belt compared with a chain. Always ask for the original Schlumpf speed-drive made in Switzerland!"

On another Schlumpf webpage, I found the following warning:

"The belt drive speed-drive comes with a special geometry of the internals, which matches the requirements of the higher belt tension, compared with a chain. Never combine a standard speed-drive with a belt drive."

Here is the opinion of Mark Sanders about the ATS and Schlumpf versions of speed-drive:
Mark Sanders wrote:Yes the ATS version of the schumpf is now very strong and very similar to the Swiss schumpf, this is used on IF Mode, Strida and Carry-Me DS. Also we used this gear in the Smithfield nocturn Folding bike race - where it did perfect service - in spite of being REALLY hammered in race conditions. The only weak point on both the Taiwanese ATS AND the Swiss version is on how it is assembled by the bicycle company - it is VITAL that the main locking ring (largest ring on the LHS with 3 slots in it) is really tight, because if it is loose the whole gear can slip and then wear the teeth that grip it to the bottom bracket.

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Re: Has anyone retrofitted a schlumpf on their strida?

Postby sdchew on Wed Sep 29, 2010 5:28 am

Hmm. Are there differences between the bottom bracket of the Strida 5.2 and the DS? Was playing around with the idea to do a 1 to 1 swap of the ATS for the Schlumpf to do a comparison before I reinstall it on the Strida 5.2.
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Re: Has anyone retrofitted a schlumpf on their strida?

Postby Guest on Wed Sep 29, 2010 9:42 pm

I think the BB shell is the same on all 5.x Stridas.


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