derail3

I want to build a new folder for commuting. I have some ideas but need some tec questions answered.
Lets start by saying that I own a Bromton and a Bike Friday NWT. I want to build something that has 20" wheels, very large gear range, internal hub gearing no derailers or slack tentioners, front hub dyno lighting, folds smaller and neater then my NWT. I know that the Birdy black would do most of this but they are very over priced in the USA, with limited support and 18" wheels.

Here is what I am thinking of building. I need to know if the gearing can be setup the way I want.

Using the Dahon MU-XL https://www.dahon.com/us/muxl.htm It comes with horizontal drop outs,
8 speed Nexus hub, front dyno hub.

Option 1
8 speed Nexus Hub in rear
Larger front chain ring
Schlumph Mountain-drive in bottom bracket

Will the Mountain drive fit in a Dahon bottom bracket?


Option 2
Rohloff Speedhub - 14 in rear

Will the Rohloff Seedhub fit in the rear drop outs with out using a tenioner? How wide are the rear drop outs?


Option 3
Rohloff Speedhub in rear
Mountain drive in bottom bracket

This is not going to happen because of cost and overlaping gears. But fun to think about.


Will any of these Options work and what are the good and bad points?

jur

I would go for a modded option 1.

A Schlumpf mountain drive steps down and you certainly don't need that - you'd end up with a huge swag of completely useless gears at the low end. Instead opt for a Speed drive which steps up. Then with judicious choice of chainring you can have perfect gearing. I wouldn't use the high speed, just the speed drive. The other one steps up too far.

BruceMetras

I'd go with option 1, but with the Speed Drive, which is a 1.65/1 overdrive... the MountainDrive is a 2.5/1 underdrive.. the Schlumpf easily fits the Dahon BB.. I've been running the 8spd Shimano and SpeedDrive since early 2006 without problems.. it's a slick set and has a gear range is over 500% .. there is another member on this board who is running a Rohloff in his Dahon XP.. AFAIK, he was very happy with his setup also..

invisiblehand

What is the efficiency comparison between Options 1 and 2?

Alex Wetmore had an interesting argument regarding the two on the YAK group a while back. I will leave the details to him -- assuming that he responds -- but I recall that the cost and gear range between option 1 and 2 is approximately the same but that the Rohloff is more efficient and has a reputation for extreme reliability.

Option 1 is probably more robust with respect to theft.

I assume that have two internal drives is inherently more complicated than a single internal drive.

The Speed Drive requires chamfering of the BB to install. The Mountain Drive has a no-chamfering option.

sprockets

I'm doing something similar. I'd look for a rebranded Dahon if you are going to be replacing components. I picked up an Avenir from a police auction for $120 (Looks like a Dahon Impulse but rebranded for Raleigh) single speed that I'm converting to an 8 speed. I haven't decided if I'm going with a Sturmey Archer or Shimano internal hub yet but the SA has a 28 tooth hub so I can use the existing rim. I'll probably replace the crank and the brakes too. All in I should have a good little bike for under $400 Canadian

invisiblehand

Finding the 28H 8-sp Sturmey Archer hub in the market might be a problem.

awetmore

The cost is really close. With the Schlumpf you are pushing the limits of your internal gear hub by running it much lower than it was designed for and you have extra gearing losses due to having two planetary setups instead of one. The Rohloff is already more efficient due to the oil bath (compared to grease for the SRAM or Shimano hubs).

If you don't want the Rohloff cost I'd just go with a SRAM i9. They are available now and the gear range is wide enough to get 24" to 85" gearing. That is plenty for most situations, including touring.

The Swift Folder is another good option for this type of bike. You can buy it as a frame kit only to save some money. The steel Swift Folder frames probably have a burly enough dropout that you could run the Rohloff with the OEM1 anti-torsion device and avoid the big ugly strap.

If you aren't held up on 406mm wheels then I'd consider a Tikit. It has an integrated rear triangle and is nice for internal hub conversions. When they (hopefully) announce an IG model it should have a new rear dropout that incorporates a mechanism for taking up the chain slack. On my Tikit I was very lucky and the chainstay length is perfect for 53/18 gearing with no tensioner.

alex

rhm

+1, but I'd also suggest you ride the bike for a month or two before you modify anything, just so you know what you're working with. I have found the SA-8 hub has a wide enough gear range for all my needs (though I must admit I been either up or down a real hill with it).

BruceMetras

I don't know of any hard data on the efficiency differences or comparisons as to how they actually relate to real world riding.. Florian Schlumpf states a figure of around 97%... I've yet to read a figure for Shimano's premium 8spd hubs.. I've seen figures ranging from the high 80's to 98% for the Rohloff.. what's not talked about as much is the total efficientcy figures that go into propelling a bike down the road... drivetrain efficientcy differences (with respect to time vs distance) is hardly significant compared with wind, gravity, traffic, body energy, rider position, or even tire choices... much is made of a 5% difference in drivetrain efficientcy, but in my tests over familiar courses, it doesn't carry over to significant time losses.

The cost is roughly 1/2 to buy a SpeedDrive and a Shimano kit against a Rohloff... the gear range of the Rohloff is 525% ... the SpeedDrive/Shimano 8spd is around 507% ... the MountainDrive/Shimano 8spd is over 750%.. both the Rohloff and the Schlumpf have excellent reputations for reliability.. I doubt that the Shimano will be close.

The Schlumpf is not a complicated device...A 14spd Rohloff in a can not much bigger than the Shimano will be complicated, but if you're equating 'complicated' with overall efficientcy, I would expect the Rohloff to be more efficient..


You chamfer the BB for the MountainDrive just like the SpeedDrive.. I am running a MountainDrive/Shimano 8spd Redband in my Downtube FS (pictured) that I use regularly on mountain trails ...

invisiblehand

Nice setup Bruce.

With regards to cost, I did a quick search the other month and came up with

Option 1:

$500 for the Schlumpf
$200 for the Nexus Redband

Option 2:

$1150 for the Rohloff

However, my initial estimate of Option 1 omitted the shifter for the Nexus plus a chain tensioner ... apparently the Rohloff comes with both. Of course, the chain tensioner may or may not be needed. If you go with the Speeddrive you need the tool (can be rented) and perhaps labor to do the chamfering. The Mountain Drive has an option that does not require chamfering. But I am unfamiliar with its advantages and disadvantages. If you go with the chamfering option, then the additional cost of that decreases the difference between the two.

My comment regarding complicated was not related to efficiency. It was just based on having two "complicated" internal drives instead of one. For example, I would think that hybrid autos are more complicated than the standard gasoline power-only auto. I don't know enough about planetary gears nor engineering to look at the internal workings of the Schumpf, Nexus, and Rohloff and evaluate.

awetmore

The Rohloff includes everything that you need (tensioner, shifter, cables, housing, etc).

For the Nexus Redband you need to include the cost of the shifter (that includes cables). You'll also need to include the cost of getting the champfers cut for the Schlumpf. The tool for doing that is not standard at most bike shops.

I think that once you add the true costs up the Rohloff is only slightly more (about 10-15%) than the Schlumpf plus Shimano. The Rohloff is a more robust hub and will almost certainly last longer than the Shimano. The gear spacing is even (where the Shimano has many large jumps, especially the 22% jump between 4th and 5th gear) and you only have one shifter to deal with. Looking at it this way I think that the Rohloff looks like a much better deal.

To save money I'd go with the SRAM i9. 340% is a very good gear range. $400 for hub plus shifter isn't a bad deal.

alex

BruceMetras

Thanks, I enjoy both bikes ... of course, YMMV, but I purchased the Shimano and Schlumpf sets (twice) online each time for the Shimano, and locally for the Schlumpf drives, and neither set went over $600 complete with cranks, shifters, cables etc. .. the Shimano hub probably doesn't include a shifter as you could opt for a twistgrip or trigger shifter, or even in a pinch, could use a friction shifter.. the prices I was getting at the time from the Rohloff distributor across the bay from me were over $1200... running a Schlumpf also allows me to change rear wheels from a relatively heavy hubgeared wheel to an ultralight deraileur wheel (which I've done) while maintaining the gear range....so that versaltility was also in the back of my mind when I started on the projects..also, the units run very quiet (which I like)... I'm not really pushing one setup over another (I think the Rohloff is magnificent), just relaying my personal experiences and what has worked for me over the last two years... today, there are even more choices available... and more on the horizon.

derail3

Bruce,

Thanks for sharing your experience with the Mountain/Speed drive and a 8 speed Nexus hub.
I see you also live in the SF bay area. I live in the east bay (Walnut Creek) Can you recomend a SF area shop to purchase and install a Mountain/Speed drive. I do not have the skills to do it my self.


James (derail3)

CHenry

C.M. Wasson, a Brompton dealer in Palo Alto does custom installation of Schlumpf drives on Bromptons. I suggest you call him.

rhm

You know, another option would be Nuvinci hub, offering a bit more gear range than a SA or Nexus. I suspect that 350% would be enough for anyone, since my SA8's 305% is plenty for me.

awetmore

Recycled Cycles (Seattle) has a used Schlumpf Speeddrive for sale for $225. Saw it there last night.

NuVinci would be a nicer idea if it didn't weigh 11lbs.