Re: [Geared_hub_bikes] Re: Schlumpf
On 5/3/2010 8:55 AM, Trina Brady wrote:OH these are geared BB/cranksets. I think I found a website but there does not seem to be alot of information on how it works does anyone have a link to a good site?
Go straight to the source
- I've got a SpeedDrive on my Airnimal Chameleon, one on a Dahon Jetstream XP and a MountainDrive (2.5:1 underdrive) on a MTB in conjunction with a Nexus Red band 8spd.. with the folding bikes, I wanted to maintain a single chain ring and not run a front derailleur and cabling .. with the MTB, I wanted a large gear range, didn't want any derailleurs or dangly bits hanging down (overall gear range 767%) and wanted to limit any duplicate gears.. I've never had a problem with any of them.. if there is a downside, it weighs more than a conventional bb for obvious reasons.. somewhere I have a picture of one sitting on a gram scale, I'll see if I can find it.. I also have a nice used one for sale, and I'm in the US.. there also are shift paddles available that make shifting easier than hitting buttons, but I never use them. I guess I should post some pics in the photo section here at some point.
So when you are riding along in the lowest gear of the 8 speed and the direct drive of the schlumpf - how does the shift to a lower gear feel in the pedals? It seems to me like a big jump.
Also - from your pictures - how is the Sachs 2 speed automatic? I have one not built into anything (as well as a few Bendix hubs, one built onto a bike that comes apart in the middle).
- --- In Geared_hub_bikes@yahoogroups.com, Mike Wilson <mwilson@...> wrote:
> So when you are riding along in the lowest gear of the 8 speed and the direct drive of the schlumpf - how does the shift to a lower gear feel in the pedals? It seems to me like a big jump.With the Mountain Drive, it is huge jump .. 250% ... a 53/21 crank... I run a twist grip with the Nexus, so, if I were to shift as you suggest, I would rotate from 1 to 6 if I wanted to keep the ratios more or less consecutive..
> Also - from your pictures - how is the Sachs 2 speed automatic? I have one not built into anything (as well as a few Bendix hubs, one built onto a bike that comes apart in the middle).
> Michael Wilson
The Automatic Duomatic is not a kick back hub.. it has centrifugal weights inside the hub that allow the hub to shift automatically at a prescribed wheel rpm... it is adjustable with a little torsion spring inside..I've actually wound some springs to fine tune for my applications.. I have the Dahon shifting at 13 mph (around 80 rpm cadence) and the Douglas at 14 mph (around 90 rpm cadence) ... shifts are fast and smooth.. the faster you pedal the faster it shifts.. it won't downshift if there is pressure on the pedals (standing going uphill but below the normal shift point)and will even shift by itself to a higher gear without even rotating the pedals (as in cresting a hill).. I wrote about it on Bike forums .
- I have one on my Greenspeed tadpole recumbent, and it really helps going up the hills!
Bruce Alan Wilson
The bicycle is the most civilized conveyance known to man. Other forms of transport grow daily more nightmarish. Only the bicycle remains pure in heart. ~Iris Murdoch, The Red and the Green