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Crankset change--advice appreciated!

Ana2010-04-28 17:56:05 +0000 #1
So after tweaking my fit, I've decided I want to try a shorter crank length since the longest part of my leg extension is not at the bottom of my stroke.

I want a 165mm and have a 170mm. I want some advice about getting it switched since I am not yet handy (or properly equipped) to do it myself.

I only have one nice road bike and have no need for a 170mm crank (after all, I'm only 5'3" with a "long torso for my height" which translates into short legs). My bike is Shimano 105 triple and is only 18 months old and has less than 1,000 miles on it. I change the chain regularly so I think it's in pretty good shape. I want to keep it at Shimano 105 or better and I know labor will need to be done but I want to stay around $200 or less. What is the standard protocol? Can I ask for a credit for the crankset and let them keep it or should I keep it and try to sell it myself?

And if so, how much credit do you think would be reasonable?

What is the best thing to do?

Any stories of others who have had their cranks changed? It's a huge hassle for me to do this since I do not own a vehicle so I can't do a lot of shopping around but there is a shop I prefer.


bike4ever2010-04-28 18:06:14 +0000 #2
You said this was a triple - is it a compact triple (50-39-30)? Or is it a traditional triple - 52-42-30?

1000 miles on the crank set will have scratches and scuffs. A shop will not be able to sell the crank set as new. If you can get credit, I would request $150. If they aren't willing to go for credit then I would suggest you try selling it for the same amount.
Ana2010-04-28 18:03:02 +0000 #3
Um...

I think it's a standard triple (52-42-30). I didn't know they made compact triples!

Thanks so much!

Do I need to worry about the bottom bracket or can I keep the one I have?
SadieKate2010-04-28 18:58:40 +0000 #4
Your shop will be able to advise you on a compatible crankset with the existing bottom bracket.

I don't think you'll get anywhere near $150 for that crank. Look at ebay for comparative values. There is a brand new one on there with a starting bid of $89 with no bids. There is a used one with two bids currently about $27.

A question: why are you already changing the chain? You should be able to get 1,500 to 3,000 miles depending on how you clean/lube the chain and your size.
SadieKate2010-04-28 18:43:13 +0000 #5
Quote:

Originally Posted by bike4ever

You said this was a triple - is it a compact triple (50-39-30)? Or is it a traditional triple - 52-42-30?

Compact refers more to the BCD or bolt center diameter which allows you to use smaller rings.

The two cranksets you mention are probably both 110/74 or 130/74 BCD (bolt center diameter), the same crank size but running different size chainrings.

Compact triples run smaller BCDs (such as mtb cranks and touring triples from Sugino and TA) and allow you to use much, much smaller rings (for instance 20-22 tooth inner ring).

www.sheldonbrown.com/gloss_bo-z.html#bcd
Ana2010-04-28 19:23:32 +0000 #6
I just examined them up close and the outer ring says Shimano 50-D (or 0, I can't tell which one it is) so I think it's a compact

It makes sense since I'm such a small person and the bike is small.

I had no idea this was going to require so many details

I'm learning new things about bike components every day!

I guess I'll be headed over to my LBS to ask them about it

Thanks for all your help
SadieKate2010-04-28 20:04:36 +0000 #7
Read my post above about compact cranks. A 50T outer ring does not necessarily mean you have a "compact" crank. Compact is the bolt center diameter.

There are and were plenty of standard triple cranks with 50T outer rings.
Ana2010-04-28 20:41:37 +0000 #8
I also found the original specs for my stock frame which is a Shimano 105 50-30-30

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