Question about Double to Triple Chainring Conversion

[pushinwind]

I have an old Atala steel road frame with a standard Ultegra 8 speed, double chainring setup. I would like to place a 105SC triple crank on to give me a little more relief in the mountains. Would anyone anticipate that I will need to puchase a different bottom bracket in order to make the switch? I'm just not sure whether the spindle will be long enough to accomodate the triple. Do they make spindles specifically for triples?

Another random question: are Dura Ace 8 speed downtube shifters compatible with ultegra 8 speed cassettes? Is the spacing the same?

Thanks.

 

[miyata610]

I think that the DA 8 speed stuff wasn't compatible with any of the other Shimano 8 speed stuff. However, I'm not sure whether it was the cassette spacing, rear derailleur pull ratios or shifter pull length that was different, or all three.

Check out Sheldon Brown.

You will need a long cage (GS) rear derailleur to take up the extra chain length.

This starts to make the whole project marginal. Have you thought about a comnpact crank (50/34) in combination with a 12-27 cassette?

 

[pushinwind]

Thanks - Sheldons website was very informative. I have been considering a compact crankset as well, I just need to crunch the numbers. Either way, my knees could use the help.