Zach Kaplan Cycles zakaplan@earthlink.net
Sun, 12 Dec 1999
The Mountain Drive and Speedhub complement each other nicely. With a Type 1 Mountain Drive and 11-34 cassette on a plain rear hub one only shifts into the underdrive on the Mountain Drive when encountering steeper climbs and then shifts back to direct drive when it levels out. With a Type 2 Mountain Drive and a Speedhub one only shifts into overdrive at higher speeds such as riding on the flats with a tailwind or descents. I would think the Type 2-Speedhub combination would be overall more efficient than a Type 1-plain hub combination because the Mountain Drive is taking a 5% efficiency loss when in the indirect gear and more time is spent climbing than descending. Rohloff recently had some efficiency tests done and the Speedhub was found to be more efficient than a derailer system in certain gears (probably due to extreme chain angle on an upright bike) and up to 2.5% less efficient in its least efficient gears which are 1st, 3rd and 7th gears where the most gears are engaged.
>Speaking of which, is it pretty easy to shift the Mountain Drive while clipped in? I tried to simulate it with my SPD clipless and it didn't appear that easy to reach the crank with my heel. I have not ridden a Mountain Drive with clipless.
I can't say how it would be with SPD pedals but with high float pedals like Bebops and Speedplays it is easy to shift the Mountain Drive while clipped in. I suspect with limited float pedals like SPDs the ease of shifting the Mountain Drive will depend on how your cleats are positioned. If biased for a heals in pedalling style it would probably be easy and if positioned for straight ahead feet it would probably be difficult. Personally my knees have no tolerance for limited float systems like SPDs so I switched to pedals with lots of free float in 1993.
Subject: Re: [trikes] schlumph Mt Gears
Date: Tue, 24 Oct 2000
List-Id: Recumbent Human-Powered Trikes <trikes.ihpva.org>
I used a 42T/60T chainring combo and an 11-27 9 speed cluster, which gave quite good gearing. There was an unexpected advantage: when new riders stopped in the wrong gear we could engage Mt Drive and start off sensibly. This is a *huge* benefit when the rear wheel has 100kg of load on it so you can't just pick it up and shift at a stop.
However there are some caveats: the 42T becomes a 16T effective in low range, and that makes the chain tension quite high. I found flex to be something of an issue, and I'm having trouble finding and fixing it (on my homebuilt). We also snapped the chain a couple of times when it was a bit worn and not lubed recently (2500kms of riding in WA, which has fine iron ore dust everywhere). That's with a rolling weight of about 200kg most of the time. I was using White Lightning on the chain every day (about 100kms) because it made a real difference, and dry lube is essential when there's Australian bulldust (very fine iron ore) everywhere, and daytime temperatures in the high 30s (around 100F, I think).
Also, after that 2500km the Mt Drive finally died. I'm not sure what happened, it just seized up so I posted it back to Switzerland. My guess is that the amount of riding it got, plus the tendency of one of the stronger riders to "kick" (power stroke < 90 degrees long) combined with the dust, heat, erratic oiling and continuous use may have ground some bits off the internals. I'll post a summary of Florians opinion when he sees it, since I suspect people here will be interested.
From: Edward
Deaton edde@freenet.tlh.fl.us
Date: Mon, 23 Oct 2000
Subject: Re: [trikes] schlumph Mt Gears
List-Id: Recumbent Human-Powered Trikes <trikes.ihpva.org>
Schlumpf Mtn Drive Type I works GREAT for wide range gearing. I'm getting some 72T chainwheels made up in 130mm BCD. Gives a range from 18.5 gear inches (or lower with bigger cassette cog) to 121 gear inches on 20" drive wheel (406 ETRTO - actually 18.5" diameter w/Vredestein S'Lick tire).
The step up type system ( Mtn Drive Type II) may work for you if you need mostly LOW gears with the occasional high gear for long downhills. It steps up 1 x 1.65 and produces an "equivalent" 72.6T chainwheel using a 44T chainring. In this case you may want to use a 30/44T chainring combination and continue to use your derailler system. Schlumpf Mtn Drive can accomodate TWO chainrings. You need to specify so you get the two-ring spider. Also designate Bolt Circle Diameter (BCD).
Expect a 2 - 5% efficiency loss in indirect range. So select which way works BEST for YOUR application.
I've had great experience with Schlumpf, both excellent service AND a unique very functional piece of equipment.
Your BB shell needs to be chamfered to accomodate Schlumpf Mtn Dr or get the torque arm installation kit.
BTW, I'm a Schlumpf dealer/installer. I have BOTH Type I and Type II in stock and can mill your BB.
My first experience w/Mtn Drive was on a BikeE NX. I currently spec them on several bikes including a Challenge Wizard, in stock.
Schlumpf Mtn Drive is the MOST ELEGANT way to get wide range gearing, imho.
Ed at Fools Crow Cycles
From: Ute
& Johannes Büttner johannes.buettner@asamnet.de
Date: Sun, 22 Oct 2000
Subject: Re: [trikes] schlumph Mt Gears
List-Id: Recumbent Human-Powered Trikes <trikes.ihpva.org>
We have it at our anthrotech (single) and our troika (tandem). It works very well on both trikes. We climb steep hills with our load: normally two children in a childrens seat and trailer. You have to realize, that your speed is slower than that of pedestrians! You don't have to catch up with them. If you want to be quicker, you don't need a mountain-drive. Problems: On steep roads you have problems with changing gears on a "normal" gear shifting (no hub shifting) as the chain-speed is too low to change the cog (I hope you understand my explanations). We have a Sachs 3*7 at the Anthrotech and a Rohloff at the troika. So we have to change (but also very carefully!) only internal hub-gears. Setup: some weeks ago the other setting has been discussed: Instead of MD-Typ I with big chain-ring in front a MD Typ II with small chain-ring. You can find it in the archive (hope so).