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Thread: 3x3 conversion

  1. #1
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    3x3 conversion

    In my quest for a lighter 3-speed it was suggested to me that I consider lacing an SA hub into the rear wheel of an old mountain bike. So I'm doing it. I had an old Univega (pretty close to bottom of the line so don't get excited) and bought an old hub. I hope to have it all put together tomorrow. The hub's been overhauled I just need to build the wheel and string up the brakes and front derailleur and it should be good to go.

    It will be a little weird looking, but it's got to be a better ride than the old steel-rimmed Fuji I was riding. I'm excited to have it done, but am slightly worried that there's something I haven't thought about that will make this project less straight forward than I think it is. Has anyone else done a 3x3 conversion?

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    old codger icithecat's Avatar
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    Rear hub spacing? Old SAs were about 115mm? There is quite a squeeze from a 126 road frame. I have no knowledge of what a univega is, so I do not know what spacing it would have.
    Godd luck and have fun.

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    The anti-rotation washer needed for the S/A hub is something the remember.you may need to cut a new one as the axle slots on the new bike are wider.

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    can't member Noah Scape's Avatar
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    Quote Originally Posted by frameteam2003
    The anti-rotation washer needed for the S/A hub is something the remember.you may need to cut a new one as the axle slots on the new bike are wider.

    This is very important. There is an axle washer (designed to keep the axle from turning in the dropout) that will fit the larger derailleur dropouts (10mm). It is not 10 mm, but the 9.5 mm version generally works fine. Check with your lbs or Harris Cyclery.

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    One of the guys at my local independent bike shop has done this conversion (with a different frame) I'm curious now, why he didn't mention the washers. The spacing on the dropouts isn't that much greater, I may even be able to crimp it in with the axle nuts and the slots are horizontal.

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    Well, I've succeeded! I have a functioning 3x3 and is it ever fun to ride. I hadn't ridden the mountain bike I used for this conversion in about 8 years, and I had forgotten how well the frame geometry worked for me. It's much more comfortable than a standard upright frame, and the 26 inch wheels mean I have a much easier time reaching the ground - I'm pretty darn short, barely 5'3, the Fuji even though it had the smallest possible frame, could be pretty precarious at stops without sidewalks.

    There were a few setbacks though. The alternashop I went to for parts gave me a few that were just wrongity wrong wrong. The first were the spokes that were 3mm too long, so I built the wheel twice, no big, I had the time.

    The second and more annoying problem was that even though I had brought in the chain wheel crank arm and the cog from my three speed hub to make sure that they were compatible and that I got the right chain , they weren't and I didn't. In fact the mechanic who had performed his own conversion insisted that they would be fine together. It was when I had the drivetrain completely adjusted and I went to test ride it that I discovered how wrong he was. So I went to a different shop, took the rear cog and the chain I had, they saw the problem right away, gave me the right chain (8-speed Shimano) and a cog from a coaster brake hub. Once I got it all back together it worked perfectly.

    The nitpicky stuff I had to tinker with to make it work:

    -I removed three or four links from the chain to get the rear derailleur away from the rear cog - the adjusting screw wasn't quite long enough to move it all the way out of the way.

    -I used modern thicker axle washers - the ones that engage with the dropouts - and seriously serrated outer lock washers just to make sure the rear axel doesn't slip.

    -It took a little futzing with the old low-end Shimano derailleurs to make the shifting smooth and get the rear derailluer aligned perfectly with the single rear cog, but once the chain was the right size it wasn't that bad.

    I've taken it for two extended test rides and tomorrow is the day that I resume my normal commute. I can hardle wait. Most of my commute is uphill and I have a feeling that my new lighter bike is going to rock it.

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    Now your going to have to do the "two rear cog thing" so you'll have even more gears---sam

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    Quote Originally Posted by frameteam2003
    Now your going to have to do the "two rear cog thing" so you'll have even more gears---sam
    That's funny. Back in the day, when I worked as a 3-speed mechanic I saw an article about modifying a hub to put several cogs on it. I was intrigued at the time but as it required welding and I was afraid of fire....
    Now it just seems silly. I only kept the 3 chain wheels on the front because I didn't want to switch out the crank. Then as it got more difficult to make the thing work I became a lot more invested in it.

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    Simple to add two cogs to a sturmey archer hub---get two shamino 6 splime sprockets and file off three of the splines on each--they are thin enough to go on the driver and still put the lock ring on.

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    Quote Originally Posted by frameteam2003
    Simple to add two cogs to a sturmey archer hub---get two shamino 6 splime sprockets and file off three of the splines on each--they are thin enough to go on the driver and still put the lock ring on.
    Good to know, but seriously, I have *Plenty* of gears now.

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