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Old 05-02-10, 04:27 PM   #1
clt1bkc
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Compact Crankset

I have a 2006 TCR Limited Giant road bike that I need to replace the crankset. It curently has a Truvativ Compact GXP 36/50. I need to replace the crakset because it is worn. I would like to upgrade the compact crankset to Ultegra FC 6750 which is a 50/34 not the 50/36 that is on there now. For all the people in the know out there is this douable going from a 50/36 to a 50/34. I want to purchase this from Ebay so I can keep my costs down. I have a new Felt I ride on weekends and I use this road bike to train during the week or ride 40-60 miles. Would it make sense to go with this more expensive crankset given the age of the bike. I see I can get one on ebay for about $130 bucks vs Performance bikes new at $299.

Would appretiate any input.

Thanks
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Old 05-02-10, 04:40 PM   #2
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yes it is doable. You have to decide how much is to much. I've put more into my 1986 Cannondale than most other people would, or maybe even I should've, but I like the bike and I believe in good parts. If your going to keep it and ride it for a long time and you have the funds then I don't see a problem with getting good parts. If your going to get a new bike shortly, then no, don't spend the money.
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Old 05-02-10, 05:48 PM   #3
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What is worn on your current crank? Any wear item on a crankset (chainring and bottom bracket) can be replaced for less cost than a new crankset (at least less than the cranks you are considering). If you do decide to ditch your current crank due to wear, let me know and I'll help you recycle it
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Old 05-02-10, 05:52 PM   #4
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The change from a 50/36 to a 50/34 is not only doable, it's trivially easy. Just switch the crank and bottom bracket and you are good to go. The gearing change is really quite minor.
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Old 05-02-10, 07:15 PM   #5
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The change from a 50/36 to a 50/34 is not only doable, it's trivially easy. Just switch the crank and bottom bracket and you are good to go. The gearing change is really quite minor.
I am not really to good mechanically inclined. Is there a website or link you can provide that shows what tools are needed to switch out the crankset and the bottom bracket? I am going to go with the ultegra ? I would like to attempt before I pay my local bike shop to complete this it does not look that difficult.
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Old 05-02-10, 08:29 PM   #6
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I am not really to good mechanically inclined. Is there a website or link you can provide that shows what tools are needed to switch out the crankset and the bottom bracket? I am going to go with the ultegra ? I would like to attempt before I pay my local bike shop to complete this it does not look that difficult.
Start here: www.parktool.com Park has tutorials for just about every type of bike repair and covers both older and newer components and the needed tools (Park's naturally).
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Old 05-02-10, 08:33 PM   #7
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You can still get a good price on a Shimano R700 Compact. This includes the BB, it's sold by a brick & mortar dealer, and it will function just as well as the 6750.

Changing cranks will require a special tool to remove/install the BB, but the same tool will work on both. You'll also need a couple of allen keys (or, ideally, allen socket heads), some grease, and some common sense so you don't crossthread the bottom bracket shell. You can go to parktool.com, sheldonbrown.com, or check out a good repair manual from the library if available. If you don't want to buy the tool(s) or have doubts about doing the job, your lbs can do it.
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