I think my cranks are going out or something. They're getting where they start to creak every time I ride and I keep tightening them and it isn't helping. They're 170mm. I do have another set of cranks, but they're 165mm. Would I notice a huge difference using those?

Probably - I went from 175 to 172.5, and I felt a difference - I like it better, but still a significant difference.

I have a 170mm crankset on my Parker and I feel a definite compromise. I switched the crankset on the Crapper once from 175 to 170 and I felt like I was on a little kids bike.

Lacking in power, lacking in leg extension, etc...

I plan to change the Parker to 175 in the distant future to make it more pedalable.

So from what you're saying, the 165 is going to be a noticeable difference in a crappy way. Hmm... This is no good.

It's all about personal preference. Will you feel the difference? YES. Will it be a positive or negative difference? That depends on you and what you prefer. I personally like 170mm, 175 just seem to long of a stroke to me and 165 feel to short. As Ed said, he prefers 175 for the longer stroke and more lever arm you get out of the extra length. It's all about you. Just switch them out and see how you like it, that is the only way you will find out if you like it or not. You can get a crank puller for around $10 on amazon and just do it yourself.

However, from my experience, if the nuts that hold your crank on is loosening it would probably be because of your BB and not the crank. Also, riding it loose will cause the crank to become whollored out meaning you might wanna consider replacing your BB and crank and not just the crank.

I thought the creaking was due to the crank tapers being worn. I'll try them on another BB and see if it continues. If that doesn't work then I'll try the shorter cranks. Thanks.

I had both my BB and my crank go bad on my MTB, it was a square taper BB, and what had happened was the nut that holds the crank arm on had loosened and was wholloring out both the crank and rounding the BB. I was told by my LBS that I could tighten the bolt after every ride and it would still end up loosening up (which is what happened for the next 2 rides lol). But I never had a creaking noise like what you are describing. I was getting at you said you keep tightening it. If you are able to tighten it time after time, then that bolt is obviously become loose. I'm not saying go out and buy a new BB and crank right now. I'm just saying that it is something you might wanna consider. What type of connection does you crank have? As I said, mine had the square taper, which is the only type that I know of that can do what I am describing. I don't know how others like ISIS and Octalink (which is what I now have would act if you road them loose.

Edit: also, if the cranks tapers are worn out they could cause wear on the BB so I wouldn't just try them on a new BB for very long because if the crank is also bad you could tear up the BB you are testing them on.

I've got 165mm on our tandem, 170mm on my touring bike, and 175mm on my road bike. I think I tend to spin a little faster on the tandem and have a bit more of a mashing pedaling style on the road bike, but the difference is pretty small and I have seen no need to switch to a different crank length on any of the bikes.

Thanks for going further into this with me, dsprehe89. The BB is actually the original to the 1994 Giant Yukon frame, so it may be the problem. I couldn't get it out due to rust, so I have just used it even though it isn't the smoothest anymore. I have a couple other BBs, though, so it's not a big deal to try a different one. It just so happens I'm swapping all of my parts over to another frame anyway, and planned on using the other cranks I have on that build-up. I'll just try these, I guess, and see if it makes a difference having them in another BB. I think maybe the cranks are worn, but what you said makes a lot of sense too. I guess I'll find out tomorrow. Oh, and yeah, this is a square taper. The cranks are early 2000s Truvativ that I got from a friend who hadn't ridden his MTB in years and gave it to me, so they've seen their use and been swapped a couple times and the BB is old and well used. Maybe they're both just worn out.

Being a 17 year old BB that has seen multiple cranks and a almost 10 year old crank that has been moved around, it is probably time for them to just be retired. BB's are pretty cheap and cranks aren't to bad either. If you replace both your crank and BB I would suggest either ISIS or Octalink. I upgraded my bike to Octalink V2 and like it, both seem to be much better designs than the old square taper in my opinion. Either way, good luck with it and glad to know I could help.