Schlumpf announces new High Speed Drive

The maker of bottom-bracket gearboxes comes out with a new model: this one gears up by a factor of 1:2.5, so the 26-tooth ring becomes a 65...UPDATED with an important correction.

Posted by Peter Eland on Monday 12 Aug 2002

High Speed Drive

The new model complements the existing Speed Drive (which gears up by 1:1.6) and Mountain Drive (which gears down by 2.5:1).

The High Speed Drive can be used with either hub gears or derailleurs:

- With a SRAM Spectro 5-speed hub you get an overall range of 560% - more than a Rohloff!

- With a Shimano Nexus 7-speed hub you get 611%

- With the SRAM 7-speed Spectro hub you get an impressive 761%

- Small-wheel bikes can also use it with rear derailleurs to get n impressive range of gears.

The High Speed Drive is fitted with a 26-tooth chainring - and this has an integral chain guard. This gived a very compact chainring unit, with a diameter of under 5", which could be useful in certain designs, especially perhaps for folders. To fine-tune the gear ratios when the High-Speed Drive is used with various different hub gears and wheel sizes, Schlumpf provides replacement rear cogs (for 3/32" chains) to fit hub gears from SRAM and Shimano. These are available in tooth sizes from 24 to 32 teeth. Alongside the 'standard cogs' already available from the hub manufacturers, this gives, says Schlumpf, a most useful range of gears for wheel sizes from 16" to 29". Another welcome innovation is the use of needle bearings for internal gearing, which should minimise friction. Current models use plain bushings for the planetary gears - which works fine, but needle bearings should be even better.

Installation is the same as Schlumpf's existing models: it slides into the bottom bracket shell, and can be fixed either using a torque arm or with 'cone washers' - for which you need to chamfer the bottom bracketr shell using a Mavic cutter (or get your bike shop to...)

We'll get a first look at the High Speed Drive in the flesh at the IFMA show in Cologne, in mid-Spetember. Details should also be appearing at but no details of the new model were up as I write this.

Schlumpf drives are made in Switzerland, but are available worldwide though specialist dealers, or direct. See his website for more. Kinetics are a UK importer. The drives aren't cheap - in the £250 region - but have a good reputation for reliability.

Posted by Dave Minter ( on Wednesday 2 Aug 2006
I expect that Dave Halliday is already aiming to fit a 52T High Speed Drive on a Brompton. What does that get to, 130T? Sounds about right.

Posted by Ben - Kinetics ( on Wednesday 2 Aug 2006
Thanks Pete :-) Florian has also recently introduced a special Mountain Drive for the Brompton with a stubby torque arm - very, very solid. The Speed Drive is available in a Brommie version too...

Posted by Span Tally ( on Wednesday 2 Aug 2006
'ere, Pete, how come all these articles are "Copyright © 2001 Velovision". It's 2002 now, y'now :-)

Posted by Peter Eland ( on Wednesday 2 Aug 2006
So it is... fixed :-)

Posted by Simon Ward ( on Wednesday 2 Aug 2006
Blimey - Pete hacking my code. He must be getting braver in his old age :-)

Posted by Peter Eland ( on Wednesday 2 Aug 2006
Just uploaded a better picture :-)

Posted by Bill Roberts ( on Wednesday 2 Aug 2006
I'm not very techie minded with these things, so perhaps one of you could help me out here. I have a 2002 Birdy Red (8 sp SRAM derailleur) which I use daily to commute on (usually, responsibility shared with another bike) over a largely very flat route through London. Now and then, it gets a holiday to the Lakes/somewhere hilly. What would be great, therefore, is a couple of lower gears and a couple of higher ones, but with the higher (faster) range being the default one for flat riding. I never use gears one and two on the flat.

My questions are:
1. What would the ideal set up be to achieve something like this (using the Schlumpf option)?
2. How easy is it in practise to use the Schlumpf changing system? The idea of aiming for a button with my heel in traffic or halfway up a hill is a bit worrying.
3. Could one use the machining option with a Birdy (rather than torque arm), it being made from aluminium?

I gather Steve Parry has a Birdy Red with a Schlumpf drive - I wonder which one he uses?

Posted by Peter Eland ( on Wednesday 2 Aug 2006
I have a Birdy Red with Mountain-drive (type 1 - 2.5 times reduction) which does exactly as you suggest - defaults to the std gear range, but with stump-pulling lows for touring in hills. Fitting it was easy enough (but requires the Mavic chamfering tool or a bike shop with one - the torque arm is much less neat on the Birdy) and shifting is dead easy - no problem at all after the first few minutes.

Schlumpf actually does a 'birdy kit' with all required spacers to get the right chainline etc.

This is all written up in Velo Vision Issue 1 by the way when I did a four-page review of my modified Birdy (it also has Magura brakes and some luggage mods).

Back issues easily available via the online shop, or phone, fax etc :-)

Posted by John Turvey (john.turvey) on Wednesday 2 Aug 2006

Posted by John Turvey ( on Wednesday 2 Aug 2006
I have a Brompton (5 speed Sturmey Archer) with Mountain Drive - this originally had a 46 tooth chainwheel and 38 inch to 86 inch gear range - in Sept 98 I installed a Mountain Drive (with mini torque arm) and a 50 tooth chainwheel - giving gears from 16 inch to 94 inch - my only problem was chain alignment - solved by longer bolts with more spacers, and a Highpath chainwheel - which should be an adequate range for most purposes. Peter Eland has a Mountain Drive on his Birdy which (I think) has been milled rather than using a torque arm.

Posted by Peter Eland ( on Wednesday 2 Aug 2006
Florian Schlumpf just emailed me - I'd misunderstood about the replacement cogs. The drive comes with a 26-tooth ring only (not other sizes). You use replacement rear sprockets to fine-tune the ratios. The story's now corrected.

Posted by Bill Roberts ( on Wednesday 2 Aug 2006
So Peter - does your arrangement keep the exact gear ratio you had when you bought the bike, plus a 1:2.5 reduction? Or . .did you decide on a chainring/rear cassette arrangement which gives you a slightly higher default range than when you bought it, plus the seven lower versions? This is the kind of thing I meant . .maybe its all covered in issue one (which I have by the way), along with the ingenious Birdy pannier holding device! ;-)

Posted by Peter Eland ( on Wednesday 2 Aug 2006
Hi Bill, yes, I kept exactly the same ratios - in fact I seem to remember I re-used the original Birdy chainring. Yes, some slightly higher gears might be welcome, but I didn't want to faff around too much in case it affected the folding.

Next mod will have to be a hub gear and preferably brakes, but I've so many other projects on the go first (converting the russian trike to disk brakes , sorting out trailer hitches etc etc) that I doubt it'll be any time soon.


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