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Old 07-12-08, 02:10 AM   #1
bendembroski
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trailer + swift = need greater gear range

I'm looking to extend the gear range on my Swift (xootr). Soon the kid will be old enough to ride along, so a child trailer is soon on the horizon.

I'm thinking about adding a smaller chain ring (38t) to where the current chain ring is, an moving the current big ring to where the chain gaurd currently is. I'll just switch the the chain over by hand, depending if the trailer is attached or not. I'd like to pair this with a wider range cassette 11-32 or 1-34.

I seem to recall that someone did something similar on the massive swift folder thread, but I can't find it now. ( That thread is huge! )

Any reason why this shouldn't work ?

Thanks in advance for any advice.
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Old 07-12-08, 06:39 AM   #2
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I have a 38t inner chainring on my Dahon, and currently switch by hand. It will work, but you might not be able to use the 11. On mine when in the 11 the chain hits the outer 53t. A front derailleur hanger has become avalable and I will install one soon. I am sure that your 38 will work.
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Old 07-12-08, 09:14 AM   #3
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Spacing front rings

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Originally Posted by Herb View Post
I have a 38t inner chainring on my Dahon, and currently switch by hand. It will work, but you might not be able to use the 11. On mine when in the 11 the chain hits the outer 53t. A front derailleur hanger has become avalable and I will install one soon. I am sure that your 38 will work.
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You can add spacer washers between the spider and the small ring. A LBS will have them. They come in different thicknesses, so try and see which ones space the ring just enough so the chain then doesn't graze the large ring.
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Old 07-12-08, 02:46 PM   #4
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Originally Posted by bendembroski View Post
I seem to recall that someone did something similar on the massive swift folder thread, but I can't find it now. ( That thread is huge! )
I'm that someone. I actually gave it its own thread, so that's why you may not be able to find it:

Click!

Short version: Sram Dual Drive internal hub gear, 11/32 cassette, Burley nutted axel hitch.
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Old 07-12-08, 11:40 PM   #5
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Thanks for the tips.

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Originally Posted by noteon View Post
I'm that someone. I actually gave it its own thread, so that's why you may not be able to find it:

Click!

Short version: Sram Dual Drive internal hub gear, 11/32 cassette, Burley nutted axel hitch.
Ahhh, yes. I did see that. However, a dual drive setup is more expense and complication than I want. I'd prefer to just add the extra chain ring and move it over by hand when the trailer is attached.

My LBS is pretty good, but they do tend to not 'get' my folder. I'm sure he'll let me try a couple setups with spacers.

Any problems with dropping chains without the chain gaurd?
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Old 07-13-08, 07:53 AM   #6
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I'd rather have just added a chainring myself, but I didn't know it was an option. Also, because of how steep this one hill is on my commute home with the trailer, I really needed to get it down as close to 20 gear-inches as I could. The numbers came out right with the Dual Drive. If not for that hill, I would have left the drivetrain stock.

No chain dropping, but I'm not sure I understand. Isn't that thing I'm looking at, on the outside of the ring, a chain guard?
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Old 07-13-08, 08:04 AM   #7
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It is.

But in order to get the two rings, it's going to have to come off. The big ring goes where the chain guard currently is, and the smaller ring goes where big ring currently is.

Make sense?
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Old 07-13-08, 08:11 AM   #8
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Make sense. I still have mine, so no chain-dropping issues. The Dual Drive replaces the rear axel. I still just have one chainring up front.

I would never do this, but I was wondering last night what kind of gearing range you'd get if you added a double chainring to a cassette AND hub gear. Like one gear-inch or something, maybe. Talk about spinning...
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Old 07-14-08, 10:02 AM   #9
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My Swift never had a chain guard and it kept dropping its chain. The Yeah had the same problem. I had to step in with guide wheels a la Gaerlan. ight now the Yeah has a guard ring and the Swift a tight barrel guide. No pics at this stage.

Contrary to common belief, this is not due to short folder chainstay length - both these bikes have chain stays of the same order as big-wheeled bikes. Rather, it is a side-ways ripple set up in the chain on shifting, especially to higher gear; this movement ripples up the chain and may dislodge the chain at the front. That's why it will tend to drop off to the outside. A worn chain will be worse as it has more side-flex capability to sustain the sideways ripple.
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Old 07-14-08, 10:26 AM   #10
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Quote:
Originally Posted by noteon View Post
I would never do this, but I was wondering last night what kind of gearing range you'd get if you added a double chainring to a cassette AND hub gear. Like one gear-inch or something, maybe. Talk about spinning...

48 gears!

I rarely use them. Just left the small ring on because I was too lazy to take it off. Now I actually have two rear wheels. One standard and the dual drive. I used the dual drive on long rides when I need a lot of gears. I use the standard wheel for everything else (I use the small chainring more with the standard wheel and just shift it by hand, been doing this since my first folder in 1998).
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Old 07-14-08, 10:37 AM   #11
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OK, I gotta know the range of gear-inches. Do you know?
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Old 07-14-08, 10:45 AM   #12
bendembroski
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Quote:
Originally Posted by jur View Post
My Swift never had a chain guard and it kept dropping its chain. The Yeah had the same problem. I had to step in with guide wheels a la Gaerlan. ight now the Yeah has a guard ring and the Swift a tight barrel guide. No pics at this stage.

Contrary to common belief, this is not due to short folder chainstay length - both these bikes have chain stays of the same order as big-wheeled bikes. Rather, it is a side-ways ripple set up in the chain on shifting, especially to higher gear; this movement ripples up the chain and may dislodge the chain at the front. That's why it will tend to drop off to the outside. A worn chain will be worse as it has more side-flex capability to sustain the sideways ripple.
So, would this be controllable by backing of a bit (or a lot) when shifting ? I'd really rather not mess around with guide wheels or the like. I like to keep things as simple as practical. I'f not, any info you have on the barrel guide would be most appreciated.
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Old 07-14-08, 10:53 AM   #13
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Gear inches.

With an 11-32 cassette, it's roughly 17.8-131.1

I usually run 11-28, GI= 20.3-131.1
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Old 07-14-08, 10:56 AM   #14
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Quote:
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With an 11-32 cassette, it's roughly 17.8-131.1
17.8!

Hmm...
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