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Old 04-30-07, 02:04 PM   #1
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Is it possible to convert a Shimano 105 double into a triple?

I bought an IBEX X-ray about 8 months ago which comes with Shimano 105 components. This summer I will be doing some bike touring and riding over mountains and I'm worried that not having the third climbing chainring on the front is going to make sections of the ride miserable. The 105 comes in a double and a triple package and I'm wondering just how similar they are. Can I simply buy the small 30T chainring and attach it to my 105 double to make it a triple? I think I'd also need to replace the front derailler. I'd rather convert my double into a triple rather than buy a whole new crankset if possible. Any advice is greatly appreciated.
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Old 04-30-07, 02:09 PM   #2
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the dbl chainring you have will not accomodate a 3rd. you need a different set of cranks.
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Old 04-30-07, 02:10 PM   #3
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You'll need a triple crankset with chainrings, new bottom bracket, front and rear derailleurs.
There is no way to just attach a third chainring.
There have been many forum postings from people trying to convert from a triple to a double. Maybe you could make a trade. Remember that the shifters need to match the cassette and chain, 9-speed to 9-speed, 10-speed to 10-speed, etc.
105 shifters are double/triple compatible, but the speeds must match the cassette and chain.

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Old 04-30-07, 08:05 PM   #4
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double to triple

I did this exact piece of work on a lugged steel specialized allez comp (1999- I think). The simpler thing to do is to change to a 11-34 casette which will give you granny-like uphill possibilities. The thing you have to do here is to also change the rear derailluer to accomocate the wider spread of the chain with the last two cogs on the casetter (30 and 34). You could also use a 12-32. These are readily availalble by bidding on ebay or special ordering from your local bike shop new. Expect to pay close to 100 for the casette and 50-60 for the larger rear derailleur.

I did convert to a triple crank and its great, but you know really, if you ride more you won't need it Good luck.
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