Internal Gear Hubs
 

If you have a Fat Bike/Trike you have probably found your gearing choices are limited. I started looking at the possibility of installing an Internal Gear Hub & discovered that my choices were the Sturmey Archer SX-RK3 3 speed for 170 mm drop outs & the Rohloff for 190 mm drop outs. - THAT'S IT! The Sturmey Hub is a favourite for High Powered E Bike Conversions with some suggesting the hub easily handles 3000 watts. The Rohloff costs more than many Fat Bikes & Trikes so I went back to the drawing board. What if there were frame adapters similar to what you can buy for installing a larger diameter back wheel? (This is a common mod for recumbent trikes.) Alternatively, what about using axle extenders similar to what are used on training wheels? For a 170 mm wide drop out you would be looking at 17.5 mm extension on either side of your hub if it were centered on your 4 inch wide rim to use a common 135 mm Internal Hub. Would the hub need to be offset to the right to allow for tire or chain stay clearance?
For a 190 mm down to a 170 mm drop out for the SX-RK3 the reduction is even less, 10 mm on either side. It would seem to me that an axle extension of less than 1/2 inch would not compromise the integrity of the axle unless it was used under extreme conditions. The axle extenders used for kids bikes training wheels are rated for 150 lbs. each & the application & stresses seem very similar to my mind. Anyone have any thoughts?

Too heavy.

Internal hubs don't shift well in cold weather.

That's a generalisation. Some hubs use grease, other uses oil. My internal hubs are fine in cold weather. They're a Shimano 11-speed on my old bike (oil), and my Rohloff hub (also oil) on the newer. If below, say, -15 degrees C, you can use a thinner oil (aka the Rohloff "cleaning" oil) if it becomes a problem.

A friend of mine had the Shimano Alfine on his Surly Pugsly. Pulled it off because it shift for crap in the winter.

Changing oil to accomodate for temperatures...sounds like a pain. Something you don't have to do with derailleur system.

Ah, the usual "a friend of mine".
You can run it year round on Rohloff's cleaning oil if you wish. Or get a Rohloff. Yearly oil change is not a bad thing, though. Just how cold does it get where he is? I have been to about -15 degrees C on my Alfine 11-speed and about -10 on the Rohloff so far. Not a problem on either.

If you set up your deraiileured bike for summer weather and then go run in -15C and below, I can guarantee you will have to adjust it.

Add to that, snow and mud will make a derailleur not shift at all. That seems a lot more work to keep clean - even on a singly muddy or snowy trip than the entire oil shift on a Rohloff or Alfine.

You complain about oil shifts, but I only change my oil once a year or so. I don't even change for winter (so not even half-yearly).

How well does your derailleur work in bad weather, mud, or even with just road grit? Have you ridden in weather that was not clear skies forever and way above freezing?

How much cleaning of your derailleur setup do do after each and every ride? Do you own dedicated cleaning brushes for your cogs and derailleur?

Also, what hub does the "friend of [yours]" run? Alfine what exactly? How many gears? 5? 7? 8? 11?

After initial cable and housing bed-in I don't have to adjust the RD. And that adjustment is just a small barrel turn. Works in snow, and dirt.
shifter cable stretch should be the same (non) issue on a Rohloff.

Chain gets wiped off after a ride and lubed monthly unless it is rainy, but that is the same for a Rohloff, unless you have a belt drive.

If you mean the cable will stretch or shrikinng with temperature, so should the housing. Assuming they have similar coefficients of expansion, thermal shrinking or expanding of the cable should be cancelled out by the same for the housing.

The only real disadvantage of an RD is that it can be damaged, especially on a wide fatbike. On the other hand, the $1,400 Rohloff is the only hub rated for MTB. The Alfine are not durable enough. But the RD has a huge advantage, it shifts under heavy load. I never damaged an RD, but shift under load all the time. So I take that. For $1,400 and the weight of the Rohloff, I can bring a whole bag of spare RD with me.

They have their place, and some advantages, but not the ones you list.

I mentioned a couple of advantages of an IGH - specifically as it pertained to prj71's claims.
And they are that: Advantages. The only disadvantage is a little more weight. I can live with that as opposed to all the disadvantages of a derailleur system.
I am still waiting for him to answer the questions regarding his "friend" and his hub.

As CargoDane says, cold weather affects derailleur systems and internal gear systems roughly equally. Just avoid breaking through ice and plunging the bike into a river at 25 degrees F. The cables will freeze instantly. (I can report from personal experience that you might end up with only a single speed and only the front brake working until you finish the ride.)

I live in WI. Below zero or below 20 degree weather is common during the winter. Like I said, he stated the shifting became real hard so he went back to the derailleur system. He had the 11 speed.

My derailleur works fine in the snow conditions and dirt or road grit. Never has been problem. I don't ride in mud and neither should you. Wrecks the trails and wrecks the brakes. Also has the potential to wreck the drivetrain.

I clean my derailleur twice a year with a brush. Oil the chain on every other ride.

Ah, the comparison with anecdotes of cheap or badly set-up drivetrains. Someone has an SARM NX drivetrain that is sh$$ty and then claims all RD systems are bad. And then someone with a cheap IGH and wrong oil, and then says all IGH are bad.

either IGH or RD can work very well in adverse conditions. You just need to:
- buy a good one of either type
- maintain it
- set it up properly

If you have problems with either type, you did something wrong. It isn't the whole category of drivetrains that is bad. Each have their place.

As far as I know the only IGH available for a 197 mm fat bike is from Rohloff and it is a pain to get. It is their A12 version, and it requires getting a frame measurement kit first, then maybe they will sell you the hub. Plan on $2K for one. I have a SRAM XX 11 speed RD on my MTB. It functions very poorly below 0F.

It does need to be adjusted at a cold temperature to be mostly functional between 0F and 32F. The Fatbike I am building up will use an SRAM Eagle GX 12 speed, and I expect it to be marginal below 0F. I haven't found a chain that is designed to run at those temperatures. The Rohloff with a belt drive would be great, but I am a bottom feeder and the GX came from my parts bin, and from eBay before that.

Assuming your RD is serviced it probably is the shifter. I had NX shifter acting up in winter... upgrading to XT solved the problem.

The chain shouldn't cause problems in cold.

I prefer the SRAM ergonomics, so I don't consider switching to Shimano to be an "upgrade". My wife's hybrid uses Shimano, and while they are a good product, I don't like the fit and feel. The shifting on my MTB is fine down to somewhere around 5F. Below that, it gets wonky. The cable and the hard stops are steel, while the derailleur itself is mostly aluminum. They expand and shrink at different rates. I can still ride, but it is not nearly as precise as at 70F.

On the subject of chains, it has been a long time since I have done anything with thermal expansion calculations, but my memory says that ΔL = αLΔT,where ΔL is the change in length L, ΔT is the change in temperature, and α is the coefficient of linear expansion, which varies slightly with temperature. The thickness of the plates is much less than the length of the pins of the chain, so the plates will shrink a lot less in thickness than the length of the pins will shrink. The chain will get tighter. I looked in the Tsubaki industrial catalog and they didn't recommend using any of their chains below 8F.

I am sure that a Rohloff with the correct oil would be OK at -20F, but when I can get a set of carbon Fatbike wheels with DT Swiss hubs + cassette for under $1,000 and had the GX derailleur and shifter in my boxes o' junk, the extra cost is not worth it to me.

This wasn't supposed to be a Derailleur vs Internal Gear Hub debate but after 11 years of West Coast Recumbent Cycling, Touring & taking people out on Fat Trikes for Day Trips, I know what causes the least headaches, adjustments, mis-shifts, stuck shifts, derailed chains & repairs because I'm the guy that usually has to find a solution. I can tell you without any doubt whatsoever that if your primary goal is a headache & problem free cycling experience go with a decent IGH. After living with both I will never, ever put one of those 100 year old French designed shifting methods on ANY bike or trike I own. That's how much of a difference the Internal Hubs make. Unfortunately for the 190 mm rear drop outs on my Fat Trikes the Rohloff is the only off the shelf option so I am doing like the E bike builders do & figuring out my own less expensive solution. The Sturmey Archer SX-RK3 is the closest hub I can find that I am trying to make adapters for & other users have had satisfactory results feeding 3000 watts through that hub. Try feeding that much torque through a derailleur. Add in the fixed chain line with an IGH & chain wear is just another headache practically eliminated. If you are happy always fiddling with your shifting, that's your choice but I prefer to be actually riding.

I never heard of a chain having problems at low temps. I guess you could use a too thick lube....

At cold the chainstay also shrinks. And even if aluminum frame contracts at a different rate than steel chain, that should be minimal. And RD have a movable cage anyway.

I've seen the posts about cold temp issues - It appears you are not riding cold, but possible sandy conditions. My first fatbike experience was on the beaches of the North Shore of Oahu with an Origin8 Crawler using a NuVinci IGH (pillbox-lean pic below). The sandy ride was addictive, and we picked up his & hers Pugsleys when we got home to Minnesota.

I've see the posts about IGH being heavy, and this is true, but this doesn't seem to be your goal if your looking for a fat trike.

The NuVinci is a continuous variable IGH - might not be exactly what you're looking for. I found the range limiting, but I'm an strong/fast rider (and I like the 100-year old French stuff :thumb:)

https://cimg5.ibsrv.net/gimg/bikefor...ea48dec324.jpg

I have some experience riding in cold temps (pic below was -28F) - I've never had an issue with my chain in the cold - I use T-9. I have had issue with the rear hub freezing up with the pawls not engaging (I've had a couple sub-zero walks). That was a long time ago with a really old bike - once the rear hub was flushed and re-lubed, I was problem free. I will say, it was entertaining for a week or two with sub-zero temps when I'd keep pedaling like a fixie to keep the pawls engages - any freewheeling would leave me struggling to reengage them.

https://cimg6.ibsrv.net/gimg/bikefor...d401e99542.jpg

NuVinci Hubs
 

I'm familier with the NuVinci as well as it's increased weight & somewhat limited range. What I am not aware of is if they come with 190 mm OLN spacing. If they do I would appreciate a link to where I can buy them. Since our trikes are equipped with 500 watt mid drives the limited range & extra weight are not a concern. Since Fat Trikes weigh in the range of 60 lbs. possibly more with the Power Assist & Battery, the extra couple of pounds of an Internal Hub becomes a mute point & the advantages far out weigh any reason for not using them. In case it is of interest, here is a chart showing the most common IGH's on the market & their best gear spreads using off the shelf standard chainrings & rear sprockets. Numbers that could be difficult to achieve using a derailleur & cassette. (scroll down) - https://mid-islandadventures.weebly.com/ig-hubs.html

The NuVinci hubs are now sold under the name of Enviolo ( https://www.enviolo.com ). You should contact them directly to find out if they can supply the hub that you want. If not, and you still want an IGH, get some money and get a Rohloff.

Bottom line...$2k for a fat hub. Not worth it.

I kind of like this pinion idea. But also pricey at the moment.

https://mythcycles.com/2020/03/10/fu...rbox-fat-bike/
https://mythcycles.com/bikes/custom-framebuilding/
http://carverbikes.com/news/pinion-g...beast-fatbike/
https://blog.gatescarbondrive.com/20...-canadian-fat/

If purely motivated to achieve a simpler bike set up, are there any recommended IGHs that comes with a coaster brake? 3 speed is sufficient. I have a Rohloff on an old 29er and it works perfectly but its overkill for what I’m building and I miss the old coaster brake simplicity.

((Fantastic pic HypnoToad!!))

Rohloffs
 

At $2000. u.s. when riding out the door, It's not going to happen. Especially when I have several trikes to equip with IGH's.
As can be seen from the Gear Inch Chart the very best gear spread you can achieve with a Rohloff is not getting that much of an improvement in gear range and that's running out of spec which voids your warranty. At least with the Alfine 11 speed I need to blow 3 or 4 hubs before I am reaching the cost of a single Rohloff. After more than 3 years of riding with the Alfine 11 with a mild Mid Drive there doesn't seem to be any indication of that happening.

Just heard back from Enviolo (NuVinci) they are not making a hub with 190 OLN spacing.

The Sturmey SX-RK3 is ordered & a local Machine Shop is making the adapters for me.
Photos to come soon.

purchased a fat bike from the Suzhou Ansbern Sports Co., Ltd. on Alibaba.

The bike has a Bafang G510 Ultra Max Mid Motor 1000W and a Gates CDX Belt.

On the first ride, the gears would not engage properly on my RSX-RK5 Sturmey-Archer IGH. Since then the issue has got so bad I can't ride the bike.

After multiple futile attempts to contact Suzhou Ansbern Sports Co., Ltd. I contacted Sunrace USA. Their technical person said that Sturmey Archer gears are not designed for mid motors therefore any damage falls outside their warranty and I should contact the bike manufacturer.

Suzhou Ansbern Sports Co., Ltd. are not answering their phone so it looks like I am hooped.

How do you live in WI and not ride in mud? I am in Ohio and half the year the entire state is mud. and wrecking trails really doesn't mater if I am riding on a trail that was made by a truck with 44's on it or 4 wheelers.

How do you deal with the ICE spray? I have had to ride single speed a few times from a frozen derailer, that was after giving up trying to keep it working stopping and clearing ICE slush off.