mrteddiamond

Has anyone tried using a front derailleur and double crank with an internally-geared rear hub to increase the range of gear ratios available over use of the internally-geared rear hub alone? If so, can you describe how you handled chain tension and chain alignment problems?

dvs cycles

I think you would still need a RD to take up the slack.

tellyho

+1. Either a RD or a single speed tensioner. I'm sure Sheldon's done this.

Sci-Fi

And you can buy bikes like that...here's one example:
https://www.schwinnbike.com/products/...ail.php?id=954

Shimano's Chain tensioner picture...You adjust the chain line by spacing the whole unit from the hanger with supplied washers...cheaper/easier to just use a rear derailleur, although some would argue the chain tensioner has a lot more spring tension. Some prefer Rennen, Sette, DMR, Yess, etc:

ginsoakedboy

And at the point where you're running a FD and either a RD or chain tensioner, what was the point of going with an internally geared hub to begin with? Seems like you're re-introducing the very type of complexities and problems of exposure to elements that the internally-geared hubs are designed to bypass.

mrteddiamond

Point taken, GSB. There's no exposed cassette, and the tensioner is simpler than the derailleur (you don't have to worry about limit screws, B-screw, or cable tension), but yeah, having a tensioner and FD is a pretty high price to pay in complexity for a wider spread of ratios.

Sheldon Brown

Right.

I used a classic Hurét Jubilee with the Shimano 8-speed on my Raleigh International, and a Rohloff chain tensioner on my Greenspeed trike with NuVinci continuously variable rear hub.

Sheldon "Hybrid Gearing" Brown

mrteddiamond

Sigh. Sheldon's done everything. Sort of saps my will to live.

mrteddiamond

In the end, was it worth it? Did the resulting drivetrain require less maintenance, in your opinion, than a pure FD/RD drivetrain?

Sheldon Brown

Yes. In the case of the Raleigh International, the single rear sprocket is a 19 tooth, should last a looooong time, and the chainline is perfect with the 52 tooth ring, which was the primary one for most riding.

I rode this bike very extensively without the derailer, 52/19, and it worked great. As my legs began to deteriorate due to my advancing MS, I added the 42 tooth ring to help with the steeper climbs. I didn't get to ride this setup very long before I became unable to handle a two wheeler, so wear was never an issue.

The other big plus of this setup is that it shifts way better than a derailer system.

On the Greenspeed trike, I only got to ride with the NuVinci a couple of miles before the snow and ice came.

The NuVinci won't work with a standard rear derailer as a tensioner, due to clearance issues with the NuVinci shift linkage. Had to substitute the Rohloff tensioner for clearance.

https://harriscyclery.com/nuvinci

Sheldon "Limited Experience" Brown
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mrteddiamond

Thanks very much, Sheldon. I was hoping to hear that. I'll give this a try, then!

stevegor

Sheldon,

I have posted this question in the folding bike forum, but, what about this possibility for a Raleigh Twenty with an SA 8 spd hub using 451 rims and a 48t chainring and wanting a smaller 2nd ring?

Sheldon Brown

That would work. I really don't recommend the 451 size, but it would certainly be doable.


However, I generally don't like derailers on folding bikes.

Sheldon "Been There, Done Most Of That" Brown

stevegor

OK thanks Sheldon, but....please excuse my annoying ignorance, can I do it without a RD or a chain tensioner?

Sheldon Brown

Nope.

Sheldon "Brevity" Brown

C_LOGAN

It is possible to do anything, but I would say that it would not work very well without a tensioner. For a normal sort of front drive setup, the chain rings are usually different sizes by around 10 teeth - 5 chain links difference would create quite substantial slack.

Sixty Fiver

I can't really add anything more except my own personal experiences with similar setups...

I don't like derailers that much and with the right internal gear hub having adequate gear range should not be an issue.

I have played with different setups and did have a dual cog on an SA AW hub and used a rear d and thumb shifter to switch ranges and also ran a Shimano 3 speed with a dual chain ring and used a derailer to handle the tensioning duties.

I liked the SA AW setup with the dual cogs and tensioner from a functional point of view but hated the cluttered look of the derailer and found I can get by pretty well with 3 speeds... most of my miles are done on bikes that have one speed and don't coast. Other people might appreciate the high/low range this setup offered.

You can run an SA hub with 3/32 chain and 3/32 chainrings if you replace the SA cog with a cog from a Shimano 3 speed and use spacers or can use 2 Shimano cogs with the existing SA spacer (this is what I did).

I believe that Harris Cyclery also carries dual cogs for 3 speeds.

With a double chain-ring you need to have decent take-up at the rear and I would use a derailer rather than a tensioner (most won't even work with this setup) as the take-up capacity is greater, there's more tension, and the derailer can be set so that it is static and keeps the chain line optimal.

You can often do this with the set screws or simply reverse a shifter cable, insert it into the derailer (backwards) and then use that and the d barrel adjuster to set the derailer position.

I might have a picture of the derailer setup I used somewhere...

dbg

Another version:

https://dbg.home.att.net/featurebike1.htm

mrteddiamond

Spot on! Thank you!

anielsen

You mention that you measured the cable distance with shifting and were going to try a brifter with a travel agent. Have you done this yet? I have an 8 speed and would love to know if someone's tried it and it worked.

abeyance

it might be fiscal overkill, but you could you a schlumph mountain drive crankset/bottom bracket. i know i spelled that wrong.

dbg

I have too many bikes. This one hasn't done a trip yet in its current config. Also my interest in internal hubs has waned a little bit (I need to sell a couple of nexus-7s on ebay so I can buy a new nexus-8 to play with).

Someday I'll do that test.

rideone

i'm going to resurrect this thread because i am thinking exactly about the hybrid gear option. I'm currently building a light touring bike from a 1960s Wally Green frame. The rear drop outs don't have a derailleur hanger and spacing is about 122 (i think). I could get a 5-6 speed cluster in there without spreading the stays too much, but, then I'd have to use a fugly bolt on hanger and no indexing! Anyway I have a SA SRF-3 rear wheel on my commuter which I thought of swapping out. In the front I'd use a stronglight 49D with 52/32 gearing for steep hills. Having only one cog in the back would significantly reduce chain rub otherwise common with a cluster in the back. . It is very Sheldonesque!

Kimmo

Since you bumped a five and a half year old thread, we're gonna need pics.

Medic Zero

+1 !

I didn't even notice the dates until I saw the first post from Sheldon Brown. That was a trip!