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Dahon folding. Going all out. Advice on double chainring.

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Dahon folding. Going all out. Advice on double chainring.

Old 05-28-20, 03:26 PM
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rscott67
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Dahon folding. Going all out. Advice on double chainring.

Made up my mind. Bought a vybe D7 a couple of years ago. Modified to a killer 11sp. Currently sporting a Single 52t front chainring. Going to move to a double. Decided on doing a 56t/40t 130BCD 170mm configuration. #1. will my shifting be horrid with the tooth jump? #2. Large chainring diameter on 56t-should I just stick to 53/39 standard and play it “safe?” And of course, I’ve only got 20” wheels.
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Old 05-28-20, 03:59 PM
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I run a 56t on my Vybe and have plenty of top speed. Sporting an 11-28 in the rear. Curious...unless you are dealing with some extreme climbing...why move to a double?
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Old 05-28-20, 04:19 PM
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No legs

Originally Posted by kayakindude View Post
I run a 56t on my Vybe and have plenty of top speed. Sporting an 11-28 in the rear. Curious...unless you are dealing with some extreme climbing...why move to a double?
I try to conquer a hill on my normal run that’s a 4+ degree 1mile gradient. Current gear range not enough. 52 front/11-32t. Plus I wouldn’t mind more top-end to boot.
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Old 05-28-20, 04:19 PM
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No legs

Originally Posted by kayakindude View Post
I run a 56t on my Vybe and have plenty of top speed. Sporting an 11-28 in the rear. Curious...unless you are dealing with some extreme climbing...why move to a double?
I try to conquer a hill on my normal run that’s a 4+ degree 1mile gradient. Current gear range not enough. 52 front/11-32t. Plus I wouldn’t mind more top-end to boot.
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Old 05-28-20, 09:46 PM
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I do 50-32-20 on Brompton. The problems I had, before modifying the cage, was with 32-20 shifts, but I do not recall any particular with 50-32. When working with rings that are not matched, you try different orientations to get positions along the ring circumference where the chain can naturally climb from the smaller to the larger ring.
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Old 05-29-20, 03:21 AM
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I have a 52/36T chainring and 11-30t cassette on my Bike Friday.
IMHO, 56T is only necessary if you are riding against roadies and riding fast.
The only times I find that I wish I had it was when road bikes try to drop my on a slight decline where they can crank that higher gear.
On a flat course, where its hard to crank 110+ gear inches for a long distance, 52/11 on the foldie isn't that bad at all.


I've done a 80+km climb of 4%-8% (probably a 10-12% somewhere on the course but not that many) on my Bike Friday and the gear combo was enough.
In fact I was the top 3 who reached the summit (the other 2 riders on road bikes)
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Old 05-29-20, 03:55 AM
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Originally Posted by 2_i View Post
I do 50-32-20 on Brompton. The problems I had, before modifying the cage, was with 32-20 shifts, but I do not recall any particular with 50-32. When working with rings that are not matched, you try different orientations to get positions along the ring circumference where the chain can naturally climb from the smaller to the larger ring.
interesting. Definitely something to consider.
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Old 05-29-20, 03:59 AM
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Originally Posted by 2_i View Post
I do 50-32-20 on Brompton. The problems I had, before modifying the cage, was with 32-20 shifts, but I do not recall any particular with 50-32. When working with rings that are not matched, you try different orientations to get positions along the ring circumference where the chain can naturally climb from the smaller to the larger ring.
Originally Posted by pinholecam View Post
I have a 52/36T chainring and 11-30t cassette on my Bike Friday.
IMHO, 56T is only necessary if you are riding against roadies and riding fast.
The only times I find that I wish I had it was when road bikes try to drop my on a slight decline where they can crank that higher gear.
On a flat course, where its hard to crank 110+ gear inches for a long distance, 52/11 on the foldie isn't that bad at all.


I've done a 80+km climb of 4%-8% (probably a 10-12% somewhere on the course but not that many) on my Bike Friday and the gear combo was enough.
In fact I was the top 3 who reached the summit (the other 2 riders on road bikes)
thanks @pineholecam. Good stuff. And yes...I have 700c roadbike envy.
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Old 05-31-20, 10:34 AM
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Somewhere in the forum I posted my upgrade for vigor d9. I made it 44/24t double with 12-34t 10 speed cassette, so I get 14.0-72.6 gear inches. I would have preferred at least 76 gear inches because I run out of gears sometimes when going on a slight downhill, but it lasts for less than a minute at a time so the loss in time savings is only a few seconds.
i custom assemble the cogs to 12,13,14,15,17,19,21,24,28,34. So I get very close spacing at the top and wide spacing at the bottom range.

The 20t jump of the double is fine as long as I had set it up well. It needs a chain catcher. The 8,9,10 gear on the small chainring will rub the chain on the outer chainring so I don't use those gears, and don't need them because they overlap in range.

I also use a SRAM yaw FD so I don't need trim. I previously had a Shimano 4700 FD before it collapsed, but I had to bend the inner cage to widen it because of the extreme angle of the FD due to the thick seat tube. It also had very specific trim settings. With the SRAM yaw FD I only had to add some spacers under the cage screw and bend the front of the cage until the tail formed the same gap width as the washers. I could also use the 4700 trigger with trim but I simply adjusted the cable slack and limit screws so that trim index didn't do anything. You can find more information here

https://www.bikeforums.net/folding-bikes/1185561-how-bend-front-derailleur-fit-folding-bike-frames-thick-seat-tubes.html

Last edited by tomtomtom123; 05-31-20 at 10:42 AM.
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Old 06-01-20, 02:05 AM
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My Helios used to be 52T-11to30T and I swap for 53/39T -11to30T as a first evolution and it was more useable on big hill but found that I spent most of my time on 53T -13T&18T. The thing I didn't like was the jumps between gears. so I put a 9 spd 11to25T which gives me plenty of smooth power between 53T-12T&17T. With 56T, you should get very nice power.
39T-21T&25T is good on hills, no need for 28 of 30. With 40T, you don't need a high number of cassette teeth.
I am looking into a 56T for mate with a 44T and it would give me a powertrain similar to semi compact 700c.

So will a 56-40 work, yes, it should thing it is the 16T max gap advised by manufacturers and some pro ride with 18/19T gap. However I would consider changing the cassette too to make the most of the double chainring and get something smoother.
Have a look on XL how the gearinch evolves as with various cassettes and chainring.
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Old 06-02-20, 12:36 PM
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Consider a 3 speed rear with narrow spaced 9 speed cassette on non Brompton set ups.
A bit heavier , but simpler and given to folding. Brommies are a bear because the narrow OCD IGH's have al kinds of issues , and Rollies $$$.
The Sturmey Archer 3X9 rear is widely spaced but with the right chainring and cassette is a good and economical option on foldies and recumbents
The hub is ~$100 and spokes ~$20. As easy a wheel build as I have ever done, would recommend it to any beginner, easier than adding a derailieur.

Getting a good feel for what ratios and spacing you need is, as the above point out , essential

Last edited by bikebikebike; 06-02-20 at 12:43 PM.
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Old 06-03-20, 01:46 AM
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Originally Posted by bikebikebike View Post
. As easy a wheel build as I have ever done, would recommend it to any beginner, easier than adding a derailieur.
Really, this was actually one of my issue when I looked into these things. yes, fitting spoke on a hub is not difficult but I always worried about straightness... fitting a front derailleur is "just" the case of fitting a static bracket and bolt a derailleur... very easy. if you have a "premium" spider crankset, just undo the 4 or 5 bolt and fit the new rings... if it s a budget, swap the crankset (wish requires specific tool) but, it is all simple plug and play.
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Old 06-05-20, 01:38 PM
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Wheelbuilding, though intimidating, has a much easier entry than you might think. It's my relaxation, and the smaller wheels are easier to true up.
You really just need a screwdriver and spoke wrench, and maybe a beer and set of googled how tos.
Its a skill you pick up as you ride more, if only just at the maintenance level (spoke and truing)
Getting a front derailleur on a foldy not set up from the factory , and keeping it happy, protected and adjusted, is a bigger deal than on a standard diamond frame.
Heel shifting without one is, um, inelegant. Costs for FD+crank+mount run ˜$80, for parts if you shop it.
Greasy finger shifting lacks broad appeal.
My goal was to get a closer set of gears, since you can get a pretty decent gear range without involving the front.
Getting the gear set up with something that suits you on any bike is a degree of customizing that all bike riders should embrace, it's just part of a good fit.

Last edited by bikebikebike; 06-05-20 at 01:47 PM.
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Old 06-05-20, 04:19 PM
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What about the spoke length? Do you figure these from some diagram? What about hub asymmetry? Are you ordering the spokes of a specific length? I have a device for rolling the thread but it is practical for when you need to replace a spoke or two - I would not really want to thread many spokes with this.
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Old 06-06-20, 10:44 AM
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Smaller wheels are more difficult to true, not easier, because the smaller length spoke requires less turns of the nipple and become very sensitive to tension, and I think the more acute curvature angles make bumps and defects in the rim more difficult to flatten, especially at the pinned joint.
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Old 06-06-20, 12:09 PM
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Originally Posted by rscott67 View Post
Made up my mind. Bought a vybe D7 a couple of years ago. Modified to a killer 11sp. Currently sporting a Single 52t front chainring. Going to move to a double. Decided on doing a 56t/40t 130BCD 170mm configuration. #1 . will my shifting be horrid with the tooth jump? #2 . Large chainring diameter on 56t-should I just stick to 53/39 standard and play it “safe?” And of course, I’ve only got 20” wheels.
If you use 'greasy finger shifting'.. No Problemo, you put the chain on the other chain ring with your fingers while Stopped../
then at the top of the hill you put it back on the big chainring.. ?

A Schlumpf speed drive has a 1.6x internal gear, so in overdrive a 34t acts like a 54t
because the crank arms are on one side of the gears chainring on the other
Physical 39t acts like a 62 t as chainring turns faster than the crankarms..

https://www.schlumpfdrive.com/index.php/home-en.html

..

Last edited by fietsbob; 06-06-20 at 12:20 PM.
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Old 06-22-20, 09:52 AM
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I have a Schlumpf MD on my ICE XL trike with a Rollie, and they compliment well. The 3x9 rear hubs like the DuoDrive get most of that done at a lower price. Not as elegant, but accessible price.
I know you are a fan of greasy finger/heel shifting, and it sure is simpler, but I don't enjoy putting back chains that have jumped, and that tells me you have more patience and forethought than I, bob.

I was able to build up from spokes cut by a great ebay guy after checking the length on several of the online calculators.
childhood_dreams, He was very Competitive with blank spokes and has quick turn around. It was fun to learn about this part of the bike, and was simpler than I anticipated with no real surprises.
Small bench spoke cutter prices have shot up, and a nicer one is hard for me to justify
Specs for the hubs are very easy to find and dishing/offset is pretty easy.
As in anything the first one is slow, at least that is what my mother tells me. The rest are easy.
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Old 06-22-20, 12:07 PM
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Or there are clamp on Front mech mounts to fit a braze on style derailleur .. CNC somewhere on the other side of the Ocean..
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Old 06-23-20, 09:55 AM
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Originally Posted by bikebikebike View Post
Wheelbuilding, though intimidating, has a much easier entry than you might think. It's my relaxation, and the smaller wheels are easier to true up.
You really just need a screwdriver and spoke wrench, and maybe a beer and set of googled how tos.
Its a skill you pick up as you ride more, if only just at the maintenance level (spoke and truing)
Getting a front derailleur on a foldy not set up from the factory , and keeping it happy, protected and adjusted, is a bigger deal than on a standard diamond frame.
Heel shifting without one is, um, inelegant. Costs for FD+crank+mount run ˜$80, for parts if you shop it.
Greasy finger shifting lacks broad appeal.
My goal was to get a closer set of gears, since you can get a pretty decent gear range without involving the front.
Getting the gear set up with something that suits you on any bike is a degree of customizing that all bike riders should embrace, it's just part of a good fit.
I upgraded my 2004 Dahon D6 (steel frame) to 20 speed using a Shimano Tiagra 2*10 set. I was concerned that getting the front derailleur set up would be a pain but it was, and has remained, pretty trouble free and I can't recall ever adjusting it in the last 6 years or so. Maybe I was lucky. The RD needs more care and attention on mine.

The biggest pain was getting the braze on front derailleur to fit on the after-market clamp fitting. It didn't fit at first, and it took an hour or so with a metal hand file to remove enough of the aluminium from the FD. A small power tool like a dremel would have made short work of it.
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Old 06-24-20, 12:39 AM
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The SRAM yaw Rd has a little more clearance to the fat seat tube, and it has a removable screw on the tail in case you need to widen it. It also doesn't require trim when setup well. The Shimano Rd are riveted at the tail so they're difficult to widen.
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