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
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.
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...
'ere, Pete, how come all these articles are "Copyright © 2001 Velovision". It's 2002 now, y'now :-)
So it is... fixed :-)
Blimey - Pete hacking my code. He must be getting braver in his old age :-)
Just uploaded a better picture :-)
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?
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 :-)
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.
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.
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! ;-)
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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