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Old 07-02-11, 09:24 PM   #1
6.2
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converting from 21 speed, to 3 speed?

Is it possible to convert the rear tire/hub/everything to a single speed, and keep the pedal gears at 3? i also have a wobble in the rear, fixed it once but it came back again after about 2 weeks.
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Old 07-02-11, 09:41 PM   #2
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OK- I guess what you're asking if you can eliminate the rear cassette and simple use the front derailleur for shifting. That's do-able, but I don't see what you'll gain. Even if you replace the rear hub with a single-speed type, you'll need to keep the rear derailleur to take up the chain slack when you shift the front chainrings.

A more practical conversion is to eliminate the front derailleur and shifter and just use the rear derailleur for shifting. It's got to be there anyway- why not use it?

In terms of the "wobble"- if you trued the wheel and it came back, you either didn't balance the tension of the spokes properly or the rim itself is bent. It's hard to tell from your description what's going on.
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Old 07-02-11, 09:53 PM   #3
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Basically I just want ansingle speed. So if I remove the deraileurs and shorten the chain to just fit so it's one speed that would work?
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Old 07-02-11, 10:07 PM   #4
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yes.
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Old 07-02-11, 10:09 PM   #5
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Ok thanks. That's what I'll do.
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Old 07-02-11, 10:18 PM   #6
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Originally Posted by 6.2 View Post
Basically I just want ansingle speed. So if I remove the deraileurs and shorten the chain to just fit so it's one speed that would work?

Yes, maybe. It depends on the bike. If it's older and has horizontal dropouts, you can do this. If it has vertical dropouts, you might not be able to get the chain tension set correctly.

The same considerations go into creating a single-speed as a fixed gear. Sheldon's page has a lot of good info: http://www.sheldonbrown.com/fixed.html
FWIW: I have a Schwinn LeTour that I converted to single-speed. It's great for cruising to the local coffee shop and other short errands.
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Old 07-03-11, 04:11 AM   #7
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Basically I just want ansingle speed. So if I remove the deraileurs and shorten the chain to just fit so it's one speed that would work?
Not that simple, need to have horizontal dropouts in order to adjust axle position for chain tension. Since it is very unlikely that the path of the chain is going to be a whole number of links.

Also, need to keep chainline in mind - the chain must run parralel to the frame, not at some odd diagonal line or it will tend to fall off the gears.

Lastly, you will need to remove all of the larger rear cogs than the one selected for singlespeed use. otherwise you risk having the chain snag on one of the larger ones and trying to climb up into a bigger circle- potential disaster when riding.


Why do you want to convert to a singlespeed anyway? Are you trying to work around broken shifters or something?
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Old 07-03-11, 05:04 AM   #8
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Why do you want to convert to a singlespeed anyway? Are you trying to work around broken shifters or something?
because they are hip!
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Old 07-03-11, 06:38 AM   #9
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How timely.

I have currently a old Fuji America which I converted to a single-speed using the Singulator to take up chain tension. However, living in West Denver, and wanting to commute to Longmont, there are some fairly robust rolling hills along Highway 93 to Boulder, which either require quite the hammer fest to get up, even considering I am using a 46T front ring, or if I switch to the largest cog in the rear, result in a spinout fest in the flats and on the descent.

My thoughts were to put a FD, and put the old 53x39 crank set on, and allow me to spin up the hills, but then switch to the 53 when I want to descend or for standard riding once I am in Boulder.

I like to use this bike for recovery rides, as it kind of forces my hand to keep to the gearing, and ensures I do not start riding to hard.

Questions

1) Will the Singulator from Soma provide enough tension?
2) I want to use Dura-Ace downtube shifters, but need a clamp, as there are no braze-ons on the Fuji? Does anyone here know whether there is anything out there?
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Old 07-03-11, 10:26 AM   #10
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'6.2' .. Why not rebuild the rear wheel with a 3 speed internal gear hub?
reads like the wheel needs work anyhow..

yea, VT a double chainring with a front derailleur will work.
.. but you still need a chain tensioner on the back,
one with a spring loaded 2 pulley wrap up
Of that difference, between the big and small chainring..
Shimano has one for Alfine group... Paul's Comp makes one too, in the US.
or just use a RD, with the limit screws turned in to center it over that 1 cog.

Yes there are band clamp front downtube shifters, go right on..
If you have a 9/8" downtube..
Back in the day, the frames used them before the trend
was to braze on a fitting..

Last edited by fietsbob; 07-03-11 at 10:32 AM.
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