Hello,

On a bike that can't take a double/triple chainring, I'm thinking of combining a three-speed Sturmey-Archer CS-RK3 gear hub and the 11-28 seven-speed cassette the bike was sold with, à la SRAM DualDrive.

But the steps between each ratio on that hub are pretty wide — from 14.3 % to 20% :-/ As a reference, it's only 13-14% on an Alfine 11 (except between the 1st and 2nd gears). An Alfine 11 hub in only 90% efficient, and I hope combining a cassette and a simpler, three-speed hub makes for a more efficient solution.

Is a cassette with closer cogs the only solution, provided it's available?

Thank you.

what frame are you thinking a 2 or 3 ring crank can't be installed onto?

search: ALTA BICYCLE BLACK BOTTOM BRACKET CONVERSION KIT ADAPTER 68MM AMERICAN TO EURO.

Will close cogs, give you the overall range you need, especially at low end?

if it will take 8 or 9 speed cassette why not go that way?

also are you sure a 7 speed will fit,? Early 7 speed cassette was pretty limited and replaced with the 8,9,10 speed width cassette

it seems to be designed for 8 or 9 speed cassettes

https://www.sturmey-archer.com/en/pr...3-silverSilver 3 Speed Disc Brake Cassette Freehub

Features

• 3-Speed internal gear cassette freehub with gear ratio of 177%
• Gear steps of 33% and 33%
• Compatible with standard MTB/ATB 9 and 8-speed cassettes
• Compatible with standard MTB-ATB left hand shifter for front tiple chainwheel
• Compatible with standard 135mm frame dropouts
• 6061 Aluminium hub shell
• Available with 28, 32 or 36 spoke holes
• Compatible with 11 to 34 teeth sprocket
• Anodised alloy finish
• Weight - 1155g

Gear Ratio
• Overall Range - 177%
• Gear 1 - 75% (- 25%)
• Gear 2 - 100% Direct Drive
• Gear 3 - 133% (+ 33.3%)

It's a folding bike, ie. not standard frame at all. With the 127mm square taper bottom bracket it came with, the derailleur has a very hard time moving from the small ring to the big (~60mm chainline instead of the 45mm expected by the derailleur). The frame make it impossible to use a shorter bottom bracket — the chain rubs against the derailleur fork.

What does that Alta part do?

Thanks for the idea. I don't know much about cassettes and what brand (Shimano, Sunrace, SRAM, etc. ) + model ("Compatible with standard MTB/ATB 9 and 8-speed cassettes") would fit that SA hub. I'll investigate if that solves the problem.

The fine steps and wide range on an Alfine 11 or Rohloff 14 are to get by with ***ONLY*** an IGH with one cog. The 3-speed IGH was originally designed to get by with only the IGH, so wide range was best (though still not wide enough for serious hills). With a cassette, you don't need finer steps within the IGH, the IGH just gives you low, middle, and high ranges. If you had more steps in the IGH, it would just give you more duplicate gears that you are getting with the cassette.

By the way, I have a folder, originally 1x7 gearing, needed lower gears for climbing. I wanted to put a triple crank in front, but the fat seat tube would not provide enough clearance at front derailleur for the cage to go in far enough on the granny gear, and a wider BB cartridge would space the high ring too far out for good chainline. So instead of mounting a 52/42/30, I mounted a 50/34 double with hollow spindle and external bearings, almost as much range and a far superior crank and bearing system in many ways. Even so, I still also had to grind off part of the excessively large inboard lip on the FD cage near the seat tube. I wanted to avoid the DualDrive due to the more complex maintenance. I might someday go to an ALL internal gear system with belt drive (and disc brakes) for winter wet weather as the grit trashes the external drivetrain and rim brakes.

Thanks for the idea. The dual speed derailleur I used first worked fine at the expense of the chain rubbing against the inboard lip on the biggest two-three cogs in the back. Maybe I should try again with a serious angle grinder to remove more.

I then tried a triple, which did solve the noise issue… but the derailleur had an even harder time reaching the outter ring to the point I often had to get off the bike to move the chain by hand :-/

Besides the extra weight, a 100km test ride with the Alfine 11 left me more tired than riding the 2*7 derailleur solution, hence my looking at alternatives. But I appreciate the total silence, the single shifter, the ability of changing gears even at a standstill, and the lower risk of hitting the rear derailleur — it happened a couple of times, speeds would no longer work correctly, and I had to pull it outwards to fix the problem.

OTHO, the gear hub + cassette means two shifters, a derailleur prone to be hit (20" wheel), and a lot of duplicates/close speeds (~ 14 unique/useful combinations out of 3*9) :-/

"I mounted a 50/34 double with hollow spindle and external bearings, almost as much range and a far superior crank and bearing system in many ways" : What would replacing the square taper BB bring? Less weight, better performance? Would you have a link handy?

the Alta adapter allows installing a square taper BB onto a bike that has an old school single piece crankset... it won't help what we now know to be your problem.

your question is really: "why doesn't the stock front derailleur work correctly?" and i'd bet that an E-type mount Front der. is what the bike needs... just a guess.

example... this may or may not be the correct part for your folding bike... it is just to give you a concept of the E-type mounting...
search: .ebay.com/itm/226344804407 on Ebay

Note: That bike came with a single chainring, that I needed to replace with a dual crankset to get a wider range for touring. Hence my problem.

Folders can be quite different from standard bikes.

In this particular case, even with the original 127mm, BSA 68mm Kenli KL-08A BB it came with, the fork of a dual derailleur can't totally move inboard (it hits the rear triangle) enough without the chain slighly rubbing againt the derailleur fork; Moving the big ring yet further outboard with a 2mm spacer or a triple derailleur makes it difficult or even impossible to work because of its ~60mm chainline.

I didn't know those "E-type" derailleurs. Provided I do find one second-hand since they're no long manufactured, can they handle a ~60mm chainline?
https://www.ebay.com/itm/226344804407
https://www.taylor-wheels.com/front-.../3x8-top-swing

Note the Max tooth count of the sprocket the altus is used for... It WILL NOT fit Your bike with that 50T ring.

can you please post a few direct-on side pics of the drive side of YOUR bike? and also a measurement of the seat tube of the frame?
why have you chosen the 127mm Bottom bracket? what is the exact Crankset model number that's on the bike now?
how much room is there between the chain ring teeth and the Chain stay/lower frame tube that runs from the BB to the rear axle? a Downlooking Pic of that area would also help us.
what model front Derailleur is on the bike now, or that you have tried to make work? the number will be on the left side of the left half of the cage...
all we have to work with is the info you can provide here...

there are other configurations of E-type mounts that allow up-down adjustments...
search: Shimano Deore LX E-Type Mountain Bike Front Derailleur
and Search: Shimano SLX FD-M660-E-type Front Derailleur
on ebay to see examples...

the Older LX versions may have a deraiilleur more suited to the larger chainring your tiny wheels need, since a lot of older MTBs used larger rings, and even those goofy oval rings...
and shopping around may find a road-curved Der that might be perfect.

personally, i'd try getting the CHAINLINE pulled in to correct things, if possible...
rule of thumb is 1/4", 6 mm clearance between the teeth and chain stay member of the frame... some have gotten away with 2-3mm... i always try for at least a 4mm gap

and Double Front Ders have a shorter tail than Triple ders...

and one more piece of info to consider.. square taper Cranksets are not all the same offset... i classify them as inny, middy, and outy... this refers to the position of the center of the spider to the inner chainring....

The front derailleur I use is a Microshift 9 speed triple. Triple because I had originally planned for that, but glad I got it anyway with my 2X as the longer cage means no chain drag on small cog/chainring combos (though I try to avoid). That FD had an unusually wide and thick top lip bent inward, way overkill in stiffness, my guess is for harsh MTB applications. I ground off what lip interfered in the locale of the seat tube, but none of the vertical cage metal, and it is still plenty stiff. It is a road style FD, as band-clamp style FDs are NOT made in the huge ~40mm seat tube diameter. It is mounted with a road derailleur adaptor by Litepro, sold by a folding bike dealer. The spring force on this FD is huge, too much for grip-shift, and even with a trigger, I need to push straight on the lever with my right thumb, not try to swing my left thumb as that will cause injury. A Shimano FD would be lower spring force, but won't fit the FD adaptor; The Microshift has a cantilevered linkage, but the Shimano linkages are in double-shear, better design, but the linkage is just forward enough to prevent proper mounting on the adaptor.

2-piece hollow-spindle cranks (first seen on Shimano Hollowtech II) have the following advantages:
- lighter weight
- bearings being external, there are more balls and/or larger, so more durable
- bearings are closer to crank, so the spindle is more loaded in shear and less bending
- easy to axially preload bearings (no slack), and can adjust over time to maintain, this greatly improves bearing durability
- easy to remove crank with only allen wrench, not crank tool
- unlike square tapers, with choice of either dry and stuck on over time, or lubed with anti-seize and sometime coming loose. Left arm clamps securely around spline.
- backwardly compatible to fit BSA/English BB threading.
- 43.5mm chainline (for 2X), dead perfect for my 130mm OLD 7 speed.
- crank with integral spindle, chainrings, bearings, was $60 on amazon, great quality. I needed to buy special bearing wrench, $20-25 I think, but is a 4-way one to handle that many bearing spline patterns.

Only possible downside: Bearing seals are close to inside face of crank arms, so dirt in there might grind, versus square tapers where the seals are recessed. My bike is strictly road, but this might be a factor for serious off-road in mud.

Rear derailleur: GS (mid) length cage works for 50/34 x 11-30, and it has capacity to do 34 cog. But still sufficient ground clearance. I used Shimano Tourney with integral claw mount as my folder did not come with an FD adaptor, it used the Dahon compact style forward of the axle. This shifted much better, gave me the capacity I needed, reversed shifting from Dahon/RapidRise to normal, and was dirt cheap at $13. "Lighter than air, stronger than steel, cheaper than dirt."




The above gives me 21-85 gear inches, or just over 400%. Others on here have gotten the same range with 1X gearing with very wide cassette range, requiring only a compatible freehub body (not 7-speed), rear derailleur design for the wide cassette, and the cassette, assuming all are compatible with your frame rear O.L.D.

I ran a gear calc with "close ratio" 52/42 cranks and the difference between the chainrings was larger than the steps on the Sturmey Archer 3 speed. Why do you think the steps are too large? Too large for what? The change between each internal gear are only two shifts on the cassette.

Uhh... you sure about that? Granted, SA 3s, even Brompton Wide Ratio (BWR), don't have enough range for my local hills. But I think the steps are still larger than 52/42, which is 24% up. SA model AW is 0.75/1/1.33 which is 33% up 1-2 and 33% up 2-3 shifts. (Do I have that right?)

Now a 50/34, which I love, is a 47% upshift. Best thing ever, when you can't fit a triple.

The diameter of the seat tube is 41mm. The 127mm BB is what the bike came with and works fine with its original 52T single chainring and 7s cassette. Considering the fork of a double derailleur already hits the rear triangle by ~2-3mm on the smaller ring, a shorter BB, while making it easy/possible to reach the big ring, would only make things worse.

I originally used a double Sora derailleur, and moved to a triple Sora to see if it solved the chain rubbing on the smaller ring + big cogs — it did while making it very hard to reach the big ring. Catch 22.

There is enough room between the small ring and the rear triangle. No issue there.

If only there were a derailleur with an ultra short cage so it could move inboard enough to avoid the chain rubbing.

I would love to, but I don't see how it could be done with the derailleur already hitting the triangle with a 127mm axle BB.

Yup, replacing the double FD with a triple did solve the chain drag issue… while making it harder/impossible to reach the bigger ring :-/

Incidently, the Microshift R9 expects a chainline of 45mm, while the bigger ring sits at 60mm with the double crankset + 127mm BB.

I did notice the triple Sora requires more force to reach the bigger ring than the dual Sora, to the point the Tourney TZ SL-TZ500 shfiter couldn't stay in place while on the big chainring and I had to use a Sunrace M90.

So IRL I shouldn't be concerned with the steps when using a 11-28T 7s cassette?

For the picture, I removed the 40T single chainring that I used with the Alfine, put the 50/34 back on along with the braze-on Sora double derailleur + Litepro clamp. As shown, with the cable unattached (ie. on the small ring), the cage hits the triangle. It would take about 2-3mm for the chain to not rub against it.

Problem solved: I didn't think of removing steel on the outside of the cage. The inboard lip on the double derailleur is pretty thick and when ground down, the cage can now move inboard enough so the chain no longer rubs.

I'll miss the silence and ease of use of the Alfine, but better performance when touring is an important point too.

Thanks everyone for the help.

While I'm at it: Do you know of an OLD 140mm, silent/quiet 7/8s hub I could use instead of the no-name hub the bike came with? Grease on the freewheel does dampen the noise… for a while, so a permanent solution would be nice.

if not available, a more common 135mm can do as shown with the Alfine 11. It only takes a couple of spacers on each side to fill the gap, along with spacers to move the disk caliper inboard

Yes, I wasn't sure if I was clear on doing the same on mine, that's why I said I ground the LIP of the cage. If I understand your pic, you ground the inboard lip near the bottom of the cage, I guess because it was hitting the chainstay there? My 3X cage is at least a centimeter above the chainstay there (positioned well for a 50/34 2X). On mine, the interference was at the extreme front/top of the lip, where it was hitting the road FD adaptor, which is pretty thick there as it also has a fore/aft adjustment slider. (Don'tcha wish they made a band-clamp FD in 40mm diameter?) Grinding the lip allowed me to remove the 4mm spacers under the drive-side external crank bearings, which caused:
- chain drop due to improper chainline
- left (non-drive-side) crank arm coming loose from spindle spline due to less clamping length...
- which also did not allow spindle end cap to engage the threads to preload the bearings

Grinding the cage lip allowed everything to work as designed, perfect.

Did you say what folder you have? Mine is an early Dahon Speed (steel) with no rear derailleur hanger.

If you simply look at the gear chart, you will see the steps do not work the way you're suggesting.

If you mean the chart in post #14, it gives percent increase between cogs, by larger cog divided by smaller cog for each step. It doesn't show the same percentages between IGH ratios, but I calculated the same way for each cog, range 2 divided by range 1, and range 3 divided by range 2. And I'm getting 33% in both cases, much bigger than the cog steps, and bigger than 52 over 42 which equals 24%.

I have respect for you based on great answers I've seen from you on many topics. On this, I still can't see it, but perhaps there is something I am missing.

Exactly — not the chainstay, though, the rear triangle, but it had the same effect. The FD could still reach the lower ring, but the noise the chain made while on the last three big cogs got on my nerves.

As for a quiet/silent hub… Onyx are supposed to be silent, but are way too expensive.

Shimano is supposed to offer quiet hubs. What model should I order, and what's the difference between road/MTB?

FWIW, the 7s cassette I currently use is a Shimano CS-HG41-7ac, mounted on a no-name OLD 140mm hub.

OOOHHHH, it's a trifold! Yeah I haven't seen a FD mounted on one, except a Bike Friday with swinging rear triangle, but those lack the vertical tube that you show interfering. Hmm, I first thought Tyrell Ive, but their rear triangle is different. The rollout fender shown I recognize from a bike on a thread months back, yep, I think that's the same one because I think I barely see the front wheel storage on the chainstay. What bike again? Is that the one with twin downtubes for the rear wheel to fit between?

Bifold, since the front wheel must be removed for a most compact fold. Not a real issue when used for touring, which is why I got it as a cheaper alternative to a Birdy or Bike Friday.

Still interested in advice about quiet/silent hubs. The sound is annoying when walking in towns.

Yep, that's the one. I should have said, "bifold with swinging rear triangle".

I dunno, I like the durability of ratchets versus roller clutches which I think is what the silent hubs use. I think cop bikes use silent hubs. Noise has never bothered me, *except* racers with molded carbon fiber wheels with big hollow spokes, those seem to act as a resonator, amplifying the ratcheting.

I don't mind replacing a hub every few years if that means a quiet/silent hub.

Apparently, "sprag clutch", used by Onyx, is a third alternative to ratches and rollers.