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Old 11-11-10, 05:26 PM   #1
thundercleese
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convert singlespeed to geared?

I have a singlespeed mtb frame that I'd like to use as an around-town bike. However, I'd like for it to be geared. It's aluminum and has track ends.

Of course, the ideal setup would be an internally-geared hub, but I'm trying to do this project using parts I already own. I have a spare 8-spd LX rear wheel that would work great.

Naturally, the frame lacks a derailleur hanger. But I've seen a few bolt-on ones. Do you think something like this would work for my purposes?



DMR 10mm Chain Tug Mech Hanger

With the hanger on the outside of my chunky aluminum track end instead of directly in-line with it, will a standard mtb derailleur shift properly? Seems like it would be too "outboard" to reach the innermost / lowest cassette cogs.

I have a 10mm -> 9.5mm adapter washer from a Surly Tugnut that should make the hollow axle play nicely with the 10mm hole in the DMR hanger. Do you forsee any other problems? If this is going to be a huge hassle, or just plain unreliable, I'll have to suck it up and take a different approach.

Seems like everyone's going the opposite direction (geared to singlespeed). Swimming upstream once again...
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Old 11-11-10, 05:37 PM   #2
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I'd vote for doing the IG hub , so as to make the bother more worthwhile.

You have 120 dropouts like single speed use, or is this a wider rear like 135 mountain Hubs usually have, on your single?

double planetary drives .. with a chain connecting them
a 3 speed in the wheel and a 2 speed IG crankset is my new favorite.

Last edited by fietsbob; 11-11-10 at 05:45 PM.
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Old 11-11-10, 05:39 PM   #3
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The spacing is standard MTB, 135mm.
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Old 11-11-10, 05:56 PM   #4
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How thick they are , is an unknown, you can ask the dealer to call and ask. of course

The widget you highlighted is certainly made for those purposes .

maybe a 7 speed cassette with a spacer behind it will let you get the lower gear
Shimano K is a good ratio set, 13-34
might even index after a while of fiddling with it.

I would convert to a solid rear axle and fix it on with nuts.
to keep the widget and the hub solidly in place.



a holdover till the Alfine 11 speeds come down in price..

Last edited by fietsbob; 11-11-10 at 06:10 PM.
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Old 11-11-10, 06:35 PM   #5
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Originally Posted by thundercleese View Post
Seems like everyone's going the opposite direction (geared to singlespeed). Swimming upstream once again...
I would bet there's a demand for SS specific mountain bikes. I'd buy one if I could. Honestly, you're probably better off selling your bike and buying a geared MTB, since now you will have to buy shifters, derailers, cassette, new chain, etc. A geared conversion is possible, but IMO not really worthwhile unless you really can't let go of your frame. Plus, does your frame have cable guides? If not, you'll have to get some brazed on (not worth it) or run housing all the way across your bike. Neither solution will be very elegant.
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Old 11-12-10, 03:32 PM   #6
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Honestly, you're probably better off selling your bike and buying a geared MTB, since now you will have to buy shifters, derailers, cassette, new chain, etc.
I've got all that stuff in my parts bin. As for the shifter cable stops, the frame doesn't have 'em. But I don't mind running housing all the way out to the derailleur-- this would be a 1x8 around-town bike, not a showpiece.

Part of the reason I want to use the frame is that it's not worth much-- it has a gash / scrape on the downtube that would probably ward off any potential buyers. Still safe, as far as I can tell, but just ugly. It was a "scratch and dent" item from the reseller.
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Old 11-12-10, 06:05 PM   #7
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I can't really see this being worth all the hassle... surely you can find another "scratch and dent" frame and build this bike up, and save this frame for an IGH bike? The more the merrier...
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Old 11-12-10, 06:57 PM   #8
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Ha! It's finally happened! The conversions are going the other way now! I can now snowboard in hell.

+1 to the idea of selling it and buying a geared MTB. Would be a lot more economical.
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Old 11-12-10, 08:02 PM   #9
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Ha! It's finally happened! The conversions are going the other way now! I can now snowboard in hell.

+1 to the idea of selling it and buying a geared MTB. Would be a lot more economical.

Haha, yes... but I wouldn't exactly say I've "gone the other way"; I simply acquired a steel singlespeed mtb to replace the alumunum one I want to convert.

I'm probably better off just getting a $99 Nashbar / Pricepoint / whatever special. Or buying something used. Nearly $30 for a fancy chain tug...a few more bucks and I'll have something solid.
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Old 11-12-10, 08:07 PM   #10
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He has all the parts but the hangar and maybe cable, but it would be more economical to buy a new bike? What?

I think that a normal derailleur should be able to span the distance fine, but I am speculating. You are basically doubling the width of the dropout on one side (as far as the derailleur is concerned, if that makes sense). if you want to be safe, I would contact DMR and ask about the thickness of the hanger. Then you can find a spacer of about the same width, put the 8 speed wheel in the dropouts, hold the spacer against the track ends and the derailleur up to the spacer. You can then move the derailleur body by hand and see if it can span the distance of the cassette. Pretty rough but it should give you a good idea. If it's marginal you might only be able to use 7 of 8 cogs.
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