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Old 11-14-05, 09:18 PM   #1
brokenrobot
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7-speed to 8-speed freewheel

I *know* this answer is already in the forum someplace - but I can't find it! Sorry for what's probably a frequently asked question...

I've got a wheel that's currently wearing a 7-speed freewheel. It's spaced at 130mm. I also have a new 8-speed freewheel in my parts box. Am I likely to run into spacing issues putting the 8 on the 7-speed wheel? My gut says no, given the OLD spacing, but I'd really like confirmation beforehand...

Thanks!

-chris
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Old 11-14-05, 09:29 PM   #2
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If your spacing is 130mm, then you should be fine. I have no idea as to whether you'll need to put a washer on the axle to keep the rim centered or not, but I'm guessing no. I recently switched a 6-speed freewheel for a 7 on a bike with 126mm spacing, and didn't have to do anything but remove one of those spacers that go into the dropouts to help you place the axle correctly. It's tight but works fine! I expect things should be even easier for you.
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Old 11-14-05, 11:04 PM   #3
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Quote:
Originally Posted by brokenrobot
I *know* this answer is already in the forum someplace - but I can't find it! Sorry for what's probably a frequently asked question...

I've got a wheel that's currently wearing a 7-speed freewheel. It's spaced at 130mm. I also have a new 8-speed freewheel in my parts box. Am I likely to run into spacing issues putting the 8 on the 7-speed wheel? My gut says no, given the OLD spacing, but I'd really like confirmation beforehand...
130 mm spacing is standard for 8-speed setups.

8-speed freewheels require a greater length of axle protrusion from the right cone, and, as a result, 8-speed freewheel setups are at very high risk for bending/breaking axles.

Generally, if you want more than 7-sprockets and also want reliability, you should go to a cassette Freehub.

If you're not clear on the distinction, see: http://sheldonbrown.com/free-k7

Sheldon "Odd Numbers Are Best" Brown
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Old 11-14-05, 11:51 PM   #4
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Wow! An answer from Sheldon himself - I'm honored!

Thanks... I knew I'd be increasing my risk of snapping an axle - but I'm a little guy, and I'd really just like to get a few more miles out of this wheelset with the parts I have on hand, so I think I'm going to take the gamble; I need to replace the freewheel anyway, and I've got the 8-speed just lying there in its box staring at me.... I *do* have a cassette wheel on order, though, so I'll be ready when the worst happens!

-chris
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Old 11-15-05, 06:24 AM   #5
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I've done this conversion (7-->8) and found no problem. Make sure you have freehubs and not freewheels though, an excellent point once again from Mr. Brown.
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Old 11-15-05, 08:19 PM   #6
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With the wheel mounted, measure the lateral gap between the 1st cog on the 7-speed and the drop-out. If you've got about 8-9mm clearance, the 8-speed freewheel will fit no problem. If there's less than 8mm, you'll need to move a washer from the left side of the axle to the right in order to move the hub to the left enough to make room for that extra cog. You'll want to end up with about 4mm of space between the 1st cog and the drop-out. Then true the wheel to recenter the rim.
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Old 11-15-05, 09:08 PM   #7
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Danno, thanks! I've got about 6.5mm space with the 7, so it looks like I'll have to respace slightly for the 8 - though it's gonna be a near thing; may try just adding a washer and spreading the frame that couple extra millimeters - easier than finding spacers!

And I've got to ask: what do you DO, man? You seem to know details of everything from steel hardness to paint formulas to metabolic paths to... on and on!
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Old 11-15-05, 09:46 PM   #8
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I've just dabbled in a lot of different things. I was one of those kids that would leave my parents inherited grandfather clock that's been in the family for 500 years completley disassembled on the floor because I was curious on how it worked. I think there's some hyperactivity and ADD going on here...

Anyway, you're pretty close on that wheel. Just look on the left end of the axle and you should see a spacer or two between the hub-cone and the outer lock-nut. Just undo the locknut and take out one of those spacers or washers, about 3mm should do. Unwind the left cone about 3mm. Then remove locknut from the right side axle-end and spin in the cone about 3mm so it's tight again. Add in the spacers/washers, lock down one side with the locknut, adjust the other side for tiny bit of freeplay and lock it down. Minor truing to fix dish and you're done! Have fun!
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Old 11-15-05, 09:56 PM   #9
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Thanks, should have been more clear. The left side as-is has only one spacer - and it's about a 9mm or 1cm size. So I'm sadly going to have to hunt for a variety of smaller spacers to do this right Not a big deal, I suppose... I've got to hit the used-bike shop for something else anyhow, and I bet they've got a coffee can of them.
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Old 11-16-05, 11:56 AM   #10
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I couldn't fit an 8-speed freewheel on a "7-speed" Campy Athena hub that has an OLD of 130mm. Well, I could fit it on but it wouldn't clear the frame when the wheel was inserted. I had to move a ~2mm spacer from the left side to the right side and redish the wheel.
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