Schlumpf Speed drive

[mill4six]

I'm getting a Birdy on the cyclescheme which I'll be using with my wife for light touring. With this in mind there's a Schlumpf option which will extend the gear range of the 8 speed (sub £1000) model for £230. (Schlumpf usually about £450). Before I buy it are there any Schlumpf horror stories, or even praise? I should know about?......

[gilesjuk]

No personal experience, but these unusual gear systems don't tend to stay around forever and make repairs more painful.

I'd stick to hub gears or derailleurs.

[thirdcrank]

Schlumpf have been around quite a while now. All I know about them is what I've read. I think they have two different models, one which gives more gears up, and one the other way. I've had my own Birdy over 10 years now and obviously, it's not the current model but it's the Elox - silver coloured - Ultgra / XT 8 speed, top of the range before they introduced the Black - 9 speed. Mine came with 56T chainwheel and the XT 8speed 11 x 18 block, gears from 36" to 91." When I eventually replaced the cassette I got the XT 11 x 30 which dropped the bottom gear slightly to 33".

I found the original gearing OK. The steps are roughly 7" and narrow enough for me. There's a picture of me I've posted a couple of times on here riding up to the windfarm over Oxenhope, something like 1:6 - wuthering heights territory. I'd not have bothered with the 30T if I'd not been changing the cassette through wear. There is a bit of a limit to the climbing you can do on a Birdy. The back end is very short so I feeel obliged to lean quite well forward to avoid my fear - which might be illogical - of pulling an unintended wheely. Also, the the suspension is a lot better suited to a smooth pedalling style, rather than anything which would cause it to start bouncing. It's easy to get the feeling you are on a rocking horse.

I'm presuming you are thinking about lower gears. I suppose 91" sounds like a low top but it's been high enough for me. A Birdy will really scoot - and that's a word I've often used to describe it. They seem to encourage brisk pedalling. Again, they reward a smooth pedalling style rather than riving the bike about which can really have you bouncing.

I presume Birdy have offered the Schlumpf option because some people said they wanted more gears. Double chainrings can cause problems on folders because of the short back end. The Schlumpf is presumably a way of giving people what they say they want. Are they now discounting it because people say they want them but don't want them that much? Incidentally, while I've been posting I've remembered that they used to offer - and may still do - a version with the SRAM 3 x 7 system, combined hub gear and derailleur. That was a cheaper option when I got the 8 speed and I never considered it - I was so impressed with the Elox.

I'd say gang warily. Hopefully, somebody with experience of the system will post. It's the sort of thing where I'd want a test ride before committing myself to buying one. Birdy have tried one or two white elephants in the past, including a hub gear with belt drive. I think Si is something of a Birdy connoisseur, although I've not heard him mentioning the Schlumpf

[rogerzilla]

The Schlumpf has been around for a good few years. It usually needs the BB shell to be chamfered or a torque arm to be fitted. Henry Sturmey dismissed bottom bracket gears (which were pretty much contemporary with the first hub gears, and in no way a new idea) 100 years ago because they have to withstand about three times the torque of a hub gear, so are either heavy or quickly destroyed. However, metallurgy is more advanced now and the Schlumpf seems to last.

[byegad]

Like all hub style gears there are some losses in certain ranges. Before the hub gear fans lynch me I know derailleurs have problems with efficiency too.

As the Schlumpf ony has two gears thing are simple. When new there will be some drag in the indirect gear, you mention a Speed Drive. Ask yourself if you will spend more time i the overdrive range or the direct? If the answer is the overdrive you may be better to get the mountain drive which has a bigger step, around 2.35:1 IIRC as against 1:1.65 for the Speed Drive. You would need to fit a bigger chain ring but the Mountain Drive has a standard web and you can get loads of chainrings from SPA Cycles if the supplier can't change it. The Mountain Drive will even take two chain rings for those looking for more gears.

From what I've found out about the drive (from only two users I know), the drag in the indirect gear gets less as you build up the miles but there is always some even after many miles. They both said that the extra drag in the lower range was not too much of an issue as they were only ever in the lower, indirect range when the normal range was too high to climb in anyway!

[thirdcrank]

... You would need to fit a bigger chain ring but the Mountain Drive has a standard web and you can get loads of chainrings from SPA Cycles if the supplier can't change it. The Mountain Drive will even take two chain rings for those looking for more gears. ...

Because of the problems inherent with the short rear triangle, all Birdys come with a pair of plastic chain guides which fit around the entire circumference of the chainring, one on either side. Birdys don't come with double clangers for the same reason, and that's presumably why they offer the Schlumpf option. Unless things have changed, the standard Birdy chain ring is 56T and the chain guide only comes in that size. (I knew somebody who managed to break his plastic guide. He tried to manage without but the bike was bordering on unrideable with the chain unshipping. The replacement cost an arm and a leg.)

[Si]

... You would need to fit a bigger chain ring but the Mountain Drive has a standard web and you can get loads of chainrings from SPA Cycles if the supplier can't change it. The Mountain Drive will even take two chain rings for those looking for more gears. ...

Because of the problems inherent with the short rear triangle, all Birdys come with a pair of plastic chain guides which fit around the entire circumference of the chainring, one on either side. Birdys don't come with double clangers for the same reason, and that's presumably why they offer the Schlumpf option. Unless things have changed, the standard Birdy chain ring is 56T and the chain guide only comes in that size. (I knew somebody who managed to break his plastic guide. He tried to manage without but the bike was bordering on unrideable with the chain unshipping. The replacement cost an arm and a leg.)

I believe that Birdys don't have doubles up front due to the lack of anywhere to mount the mech and the fact that the swing arm would hit the inner chain ring (or you'd have a big QF) rather than the shortness of the back end. I've seen a few Birdys where the owners have done a little 'engineering' to fit a front mech and double chainset and they've not reported problems with the chain unshipping - the front mech keeps it in place.

[les-roberts]

I have had a speed drive on my 3 speed Brompton for about 5 years. Total reliability no noticeable drag between direct drive and the stepped up gears. There is some overlap so it gives 5 widely spaced gears, as I live at the top of a steep hill ideal.
I have used the Brompton with the speed drive for quite long trips, probably 50 miles max but that’s my limits rather than the bike and set up.
The speed drive needs to be properly fitted Bikefix in London supplied and fitted mine.
I think I prefer the speed drive to my Rohloff Brompton modified by Steve Parry. I would like to try the new Brompton wide ratio hub as a six speed to see how it compares.
Anyway don’t worry about reliability it’s simply not an issue.