Bicycle Mechanics - Fitting a triple

I'm just installing my first ever triple crank. I notice that the distance between the granny ring and the chainstay is very tight (maybe only a millimeter or so), although it doesn't touch. Is this normal, or does it indicate that the spindle is too short? My current spindle (111mm) was bought separately from the chainrings/cranks, which themselves were made up from an old double plus a newly purchased granny. If I do indeed need a longer spindle, what length would make a noticeable difference - 113mm, 116mm? The current chainline is about 45mm, if that's relevant, and the tubes are regular diameter (this is an old frame from 1982).

Thanks for any help you can give me. I used to swap out doubles all the time in years gone by, but this triple is really giving me a headache!

Yeah, 1mm is too close, especially if there is any flex in the BB or the cranks.

You may need to go quite a bit wider. Sheldon Brown indicates that for Shimano road triples, 45mm is the chainline, but because you have made up unique crankset you may need to look at a chainline range of 47.5 or slightly more. I suppose doing the calcs, that would mean a spindle of 116mm as you suggest, and moves the granny a total of 3.5mm away from the chainstay.

I know my old road triple set-up on my Fuji had a 118mm BB, and I might be inclined to go that wide to ensure chainstay clearance in your case. But then you might compromise derailleur range and line to the rear cogs.

Check Sheldon's site for the correct BB spindle length for your triple crank. He's got it all.

http://www.sheldonbrown.com/bbsize.html

For Shimano Octalink- specced cranks, ISIS splined or standard square tapers, its usually 110-113 for doubles and 118 or so for triples. But, yes, just check the speccs for your crank.

And, kinda crucial, is your BB 68 or 73MM?

You can use a spacer to give more clearance on the right side if it won't cause the left arm to hit the chainstay. You may not have a problem anyway. I have a single speed mtb with no more than 1mm between the chainring and the stay.
http://thumb9.webshots.net/t/55/55/9/47/62/2244947620068014369ZmdEeX_th.jpg (http://sports.webshots.com/photo/2244947620068014369ZmdEeX)

You can use a bottom bracket spacer to move the crankset out. These are available in various thicknesses, you may only need a 1mm spacer. These work well and are easy to install. My LBS usually keeps a few in stock. I used a 1.5 to correct a chainline problem on my wife's triple.

Al

You can use a bottom bracket spacer to move the crankset out. These are available in various thicknesses, you may only need a 1mm spacer. These work well and are easy to install. My LBS usually keeps a few in stock. I used a 1.5 to correct a chainline problem on my wife's triple.

Al

Why didn't I think of that? :rolleyes: