Tandem Cycling - 8sp hub in 7sp Cannondale?
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03-28-08, 01:46 PM
I converted my 7sp spaced cannondale to a new 8sp hub a few years back and every things been great. it shifts fine and works great. it's a bit of a stretch to pull and set the hub since the spacing is for 7sp, but it's easier than unbolting the old 7sp freewheel hub it had before. Question is, does anyone have any experience with any long term ill effects of riding the rear end stretched like this. I know Sheldon Brown didn't recommend it, but it doesn't take much force to get it to fit and nothing rubs, plus i'm enjoying 8sp shifting (now converting to campy centaur ergo shifters)
Sounds like a 5mm stretch? If the bike is steel (Cannondale steel??) you could put a leg and
a couple of arms into the job and just over stretch it enough to reset to a wider stance.
More accurately you could use a 1/2inch allthread, a couple of nuts and washers and a caliper
to do the same thing. There is a small risk of splitting the seams at the BB. OTOH if this is
a typical aluminum frame, your risk is a bit higher as aluminum has a fatigue limit and every
mount dismount cycle increments. Failure will be sudden and catastrophic. Good thing aluminum
is up to $0.85 per pound scrap, as the frame will then be worth $6-7 at that point. Al can't be
sprung to a wider stance. As long as it is easy to do the risk is low in reality and you are not
shortening the frame life a whole lot. No one could say how much and the bike is steadily
shrinking in value as the 10spd era marches on. I would say continue to do it.
Parenthetically I have a 5spd Teledyne Titan frame that has to be sprung to
mount the 9-10spd wheel I am using and it takes a bit of effort to put the
wheel back in. I had a Peugeot PX10 531 frame that I put an 8spd on and
it was a real wrestling job to get that wheel back on the bike. About 2x the
amount of muscle needed. I can get the wheel in with both arms pulling the
Titan rear triangle but to put the wheel in the Peugeot I have to sit down,
put a foot on one side pull with an arm and manipulate with the other arm.
Neither bike seems to care about the off angle fork ends.
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