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8-Speed cog in a 126mm tail?

6500 Views 8 Replies 3 Participants Last post by Dave Hickey, Mar 16, 2007

Mr Bentwrench

Discussion Starter · Mar 15, 2007

Wanting to update my 7-speed downtube shift Vitus with some spare Shimano 600 8-speed lever shifters and a spare 8-speed cassette. Will a Shimano 8-speed cassette fit into a 126mm spacing?

I'm thinking you need 130mm to handle the 8-9sp gears and the Vitus is NOT the frame to try to expand.

If stuck with the 7-speed cassette, is there a way to limit my 8-sp 600 shifter's 'throw' to just 7? If possible, would it be a mod to the shifter's internal mechanism or just limiting the derailer's max or min to just 7 of 8?

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Dave Hickey

· #2 · Mar 15, 2007

Mr Bentwrench said:
Wanting to update my 7-speed downtube shift Vitus with some spare Shimano 600 8-speed lever shifters and a spare 8-speed cassette. Will a Shimano 8-speed cassette fit into a 126mm spacing?

I'm thinking you need 130mm to handle the 8-9sp gears and the Vitus is NOT the frame to try to expand.

If stuck with the 7-speed cassette, is there a way to limit my 8-sp 600 shifter's 'throw' to just 7? If possible, would it be a mod to the shifter's internal mechanism or just limiting the derailer's max or min to just 7 of 8?

An aluminum Vitus 979? I have one that runs 8 speed. If you want to run 8 speed, you'll need a 130 rear wheel. There are no problems stretching a 979 to 130. The stays are quite flexible.

In answer to your shifting question, yes you can use 8 speed shifters to shift 7 speed. The spacing between cogs on 8 vs 7 is almost indentical. You just don't use the extra click. I've done it many times

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Mel Erickson

· #3 · Mar 15, 2007

I'm running a 130 wheel with 8spd on my '85 Cannondale, no problem. You should have no difficulty putting the 130 wheel in. It will probably be tight and need to be helped in a bit but it should work without actually resetting the rear triangle (not really advisable on an alu frame).

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Mr Bentwrench

Discussion Starter · #4 · Mar 15, 2007

Although the Vitus already has a reputation of being 'quite flexable' :wink:, I'm just reluctant to stress an older bonded component frame and distroy such a nice riding and mint cond, all polish classic. In summary though, a 7-sp is all I can fit into the stock 126mm tail and I need 130mm for an 8/9/10 stack. :sad:

Big help and thanks guys! ... and glad I could remember my user name and password!

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Mel Erickson

· #5 · Mar 15, 2007

I'd do it and not think twice. Think about it. You're only opening the stays 2mm on each side. If it can't withstand this it's likely to fall apart anyway. But, I understand if you don't want to do this. I'm riding an older Schwinn Circuit as a 7spd because I really like the mint Shimano Sante group. It's fine with 7spd. Gears are definitely over rated.

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Dave Hickey

· #6 · Mar 16, 2007

What Mel said.... With the wheel out of the rear stays, grab the stays with your thumb and forefinger and squeeze. You'll see just how much give there is.....I use this test on any bike. If the stays won't budge, don't try stretching them. If there is plenty of give, go for it...Trust me the Vitus has plenty of give....

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Mr Bentwrench

Discussion Starter · #7 · Mar 16, 2007

Good point and tips from both of you. Thanks. I'll take another run at it now.

This particular Vitus is a pretty thing with a full polish frame w/ french blue tape and accent. The original full 600 componentry is mint condition so the move from 7sp downtube shifters to 600 8sp ratchets would be subtle, still period correct... and a LOT easier (and safer) to ride.

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Mel Erickson

· #8 · Mar 16, 2007

I don't know why you think it would be easier and safer to ride with 8spd rather than 7. My favorite bike to ride is my 7spd downtube shifter Schwinn Circuit. I find the shifting better than any of my other rides (including my 10spd Chorus/Record). I certainly don't consider taking a hand off the bars to shift a safety issue and it's barely less convenient. I like the positive and fast shifts better so the ease part is a wash.

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Dave Hickey

· #9 · Mar 16, 2007

Mr Bentwrench said:
Good point and tips from both of you. Thanks. I'll take another run at it now.

This particular Vitus is a pretty thing with a full polish frame w/ french blue tape and accent. The original full 600 componentry is mint condition so the move from 7sp downtube shifters to 600 8sp ratchets would be subtle, still period correct... and a LOT easier (and safer) to ride.

This picture is a couple of years old but this is my Vitus running 8 speed Dura Ace. The wheels are made from Dura Ace 7700 9 speed hubs

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