Crankset change--advice appreciated!

[Ana]

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.

[bike4ever]

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.

[Ana]

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?

[SadieKate]

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.

[SadieKate]

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).

http://www.sheldonbrown.com/gloss_bo-z.html#bcd

[Ana]

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

[SadieKate]

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.

[Ana]

I also found the original specs for my stock frame which is a Shimano 105 50-30-30

[aicabsolut]

since the longest part of my leg extension is not at the bottom of my stroke.

Just swap out the crank arms. Keep the same rings, spider, and BB. Get your LBS to locate you some Shimano 165mm crank arms. That's your cheapest option. You're not going to get any rebates at the shop from a crankset with 1000mi, and selling a 105 crankset isn't going to get you much.

[Ana]

Just swap out the crank arms. Keep the same rings, spider, and BB. Get your LBS to locate you some Shimano 165mm crank arms. That's your cheapest option. You're not going to get any rebates at the shop from a crankset with 1000mi, and selling a 105 crankset isn't going to get you much.

Thanks for the input! I was uncertain whether only changing the crank arms was an option They are difficult to find online

I always feel better knowing what I want before I go in so I don't feel like they are trying to sell me something I don't need

[aicabsolut]

Yeah it's no problem. They may have to order them for you, but they should be able to do that. My bike came built with the wrong sized crankarms for the frame size, and the shop just ordered a pair in the right size and installed them. Then they dealt with the bike manufacturer about getting reimbursed (because the bike was sent to the shop with the wrong parts).

You don't even have to go with Shimano if you don't want to. I believe FSA crankarms are compatible. Maybe you'd need an FSA spider too, but your current Shimano BB and rings will definitely work. Of course, FSA will probably be more expensive, especially if you go with carbon. With a 105 crankset, I wouldn't really worry about upgrading parts of it. Either keep it the same and save cash or upgrade the whole thing. I just rode a new 105 crankset a couple weeks ago, and the thing is so flexy compared to Dura Ace or my old FSA crankset that it's not really worth the cash, IMO, to put nice crankarms on flexy rings.

As you have noticed, it may be hard to find 165mm cranksets anyway, stock. So ordering the cranks separately and sticking with the same level of componentry is probably the way to go unless you want to go all out with the upgrades. In that case, you can see if your shop can custom order you a new triple (in Ultegra or DuraAce 7800 (old DA), say) with 165mm arms or swap out whatever stock arms they can find with 165mm ones for free.

[Cataboo]

I could be wrong - but I'm 5'1, use 165 mm crank arms, get knee pain with 170mm crank arms, and I usually have my saddle all the way back on the seat.

My experience with small bike frames is they usually adjust the seat angle to 74 or more degrees which makes it so that if your seat isn't all the way back, it feels like you're really sitting right over the cranks... and while short people are shorter, their femurs are usually not that short that it's comfortable to sit right over their cranks. I usually have my seat all the way back to compensate for the seat angle and I just use a shorter higher stem to bring the handlebars closer to me.

I just bought a frame with a 73.5 seat angle and I find the positioning of the seat to the cranks much more comfortable and natural.

[Ana]

Wouldn't it be wonderful if we could tweak the geometry of our frames too?

Okay, so I'm dreaming big....can you blame me?

I will report back (perhaps in a new thread, we'll see) after I get fit I'm excited to get fit (except for the spending money part..)

If they tell me the geometry is all wrong, does that mean I can get a new bike? I'm so drooling over those Seven Gateway Program bikes!!!

Must...divert...attention...

[aicabsolut]

I could be wrong - but I'm 5'1, use 165 mm crank arms, get knee pain with 170mm crank arms, and I usually have my saddle all the way back on the seat.
.

Yes, that makes total sense. However, the OP isn't complaining about knee pain, so I'm not sure the crank length is the problem. Maybe the seat tube angle is part of it. Maybe she needs to adjust her reach shorter unlike my first guess, but I still think it's more likely a reach issue causing back and shoulder pain than a crank length problem. The cranks could be wrong for her build, but I don't think that's related much to the pain issue here.

[Bluetree]

Ana, I have to echo the posts about getting a proper fit, especially with a fitter who has access to a Fitcycle.

Like I said earlier, I'm also 5-1 and needed sub-170 cranks. I always thought I needed 165s but when I was thoroughly measured, it turns out I needed a 167.5 because of the length of my femurs. Since I was making a substantial investment at the time (Red cranks + ceramic BBs) I wanted to make sure -- and I'm glad I did!

Also, I suggest you hook up with some local cycling clubs. Their members can be a treasure trove of good information (finding the most reputable shops/mechanic, how to get parts in your neck of the woods, borrowing/trading components, etc). Most have a forum or email list that is handy to get information out. My club is a tremendous support group for me and have always responded if I wanted to try out a new wheelset, saddle or stem. No need to go it alone when working on a bike fit!