I found a presumably 3rd party Speed Drive upgrade kit on a Taiwanese auction site. It includes not a genuine Schlumpf but an ATS Speed Drive, a sprocket (which looks like a deadly ninja weapon ), an eccentric bottom bracket, and a belt. The item goes for TW$16500 (about US$516) but sadly the seller does not ship oversea. If this thing actually works well, I hope someone can import it to the US and sell it here.
I’ve just fitted a Schlumpf Speed Drive to my Strida Mini, using the original belt ring and some engineering work costing about £50. I will be posting pictures and more details soon…
May be It would be a new chance for everybody that owns a Strida Sport Duo instead of fitting large wheels, because the mudguards dont match, the big tyres are less comfortable, more expensive and less available. As the fitting 18" wheels purposse in the SD is rising the speed, may be, we could get the same speed in our duos with a different alternative.
The alternative would be to fit the original plastic Strida front pulley to the current Speed drive and keep the 16" wheels. Unfortunattely, the original Strida 5 plastic pulley has four inner spokes instead of the five ones the miny pulley has. One solution would be to use the not holed Strida 3 plastic pulley, although I dont know if , after chopping, the structural strengh of this pulley would be enough.
At last, We could use the new alloy strida 5 pulley (optional), chopping it and adapting an intermediate thin alloy plate.
Andy B: Awesome mod! Mini owners are lucky that their crank arms are 5-bolt just like the Schlumpf SD. Us 5.x owners can’t do the same unless we somehow manage to find a 5-bolt front sprocket to replace the existing 4-bolt one.
A quick update regarding the Schlumpf Speed Drive kit for Strida: I heard the first batch of the kit was almost ready. The delay of release was due to a redesign of clutch geometry. The change was deemed necessary to compensate for the higher tension on the belt (vs. a chain).
If the technical issue is indeed true, it helps to explain why Sports Duo has been produced in such a small quantity. But it may also raise a red flag on the durability of existing Sports Duos.
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.”
I’m thinking here that the belts don’t have the slack and give that a chain has here which can probably stress out the intricate gearing they have inside. Those belts are very strong and don’t stretch at all.
I thought with the snubber correctly adjusted (ie 0.5mm gap max, but not touching the back of the belt) … that belt tension can be much lower - on par with a chain. Maybe Schlumph dont get this ?
The price seem high - the china made one appears to be much less - but only available on a new bike.
For me, spending 400 Euros (or so) for 2 gears is too much for not enough, so I won’t be bothering. But it’s a useful link for anyone who wants to look further…? Please post here, if you go further?
It still baffles me. There’s a huge volume available on the Strida; that whole area of the drive cog, below the crossbar, times the width of the pedal axle? You could get a load of big gears (lower torque, higher efficiency?), and axles and springs and bearings in there?
If this was a Dyson product, gears would have been available years ago…
(2 other pet modifications I have in mind:
Folding seat. If it hinged below the front of the saddle, close in to the frame, to lie alongside the back strut… The whole bike would eat sooo much less volume… The saddle would be mounted on a strut, which would be parallel to the ground when unfolded. This strut could be about 600 mm long… And used to hang luggage off… Which is much more efficient than a rack to stand luggage on?
Wheeling the Strida folded? It’s twice the pain it needs to be, because you have to hold it upright in two dimensions. One simple fix might be to buy a pair of Strida wheel magnets, and fit them to either end of a short flat bit of plastic, and, when folding, instead of clipping the wheels together, click each wheel to an end of the strut, making a “very short wheelbase Strida”, that would be stable “front to back”, and would only need supporting left/right. Immediately, you stop carrying the weight when wheeling it folded…)
I think the point of Strida is SIMPLICITY, and the design aims to be pure, clean, simple and Iconic. There are plenty of bikes with zillions of gears - but its interesting the fixie urban movement is also going simple 1 speed. I beg to differ about dyson products: yes they are highly innovative, and extremely well marketed, but the design style - with all the innards out on display - is not to everyone’s taste - like seeing all your intestines and ugly bits on the outside of the human form
2 speed locally made Shlumpf geared Strida’s are also slowly coming to market from Ming - they work out cheaper than buying a Strida and then adding the gear. But the gear upgrade direct from Shlumpf will be super quality swiss engineering… I guess give them all time to get these to market - manufacturing, shipping and distribution is not as instant as the internet.
I saw a pic of a folding Saddle on a Strida …sorry cant find: I think it was on a picture from Taipei show a couple of years ago: The seat folded down to be parallel with the tubes: yes it did make the bike slimmer at the top, but also more complicated - with big safety issues: if not locked could drop the rider and lots of finger traps.
The idea of setting the wheels apart when folded is interesting - But I have no problems with the stability of my folded Strida. The best tip (from this forum I think) is to roll the bike as vertically as possible - with most weight through the wheels, not the arms, this means hold by stem with a bent arm, Or: hold by the front of the saddle. I think, Having the 2 wheels together makes the folded Strida more easy to manoeuvre - in fact just like the Dyson Ball vacuum - we’ve all seen the adverts for, steering around furniture etc.
I recently emailed Schlumpf Innovations to inquire about a Speed-Drive for my Strida 5.0. They were very helpful, and promptly replied with a quote of 821 CHF (Swiss Francs) plus 82 CHF shipping to the USA, for a total of 903 CHF.
821 CHF is currently about 577 EUR or 707 USD, 777 USD with shipping to the USA.
That’s higher than I expected. Has the price gone up from the 519 EUR quoted earlier in this thread, or is this currency fluctuation?
with kind agreement of Mr. Florian Schlumpf, mechanical engineer in Switzerland, I would like to publish parts of the conversation between Mr. Schlumpf and me a few weeks ago:
Me: “… as an enthusiastic owner of a Strida 5.2 I would be highly interested in where to get a speed drive and in knowing the costs of the precious piece. Sharp, possibly not really competent, tongues here in Austria claim the Strida MAS does not operate properly.”
Mr. Schlumpf: “The sharp tongues are not totally wrong: years ago we made a licence agreement with a Taiwanese company.
Presently, these gear drives are mounted into the Stridas - unfortunately with little success since the quality leaves a lot to be desired. For this reason we decided to produce a tailor-made alternative including the excentric fitting for the Strida, which is now available and works faultlessly. However, with “made in Switzerland” and 5 years full warranty this part is also a little more expensive.”
I received the following parts:
Speed drive and belt
Tool set “maintenance”
Info sheets, mounting instructions
In my case, the price was exactly 553,27 Euro (speed drive plus toolset minus 4 % when paid within 10 days).
And praise the lord if you are NOT going to be charged for customs duty (in my country about 20 %).