Pheard

I believe I need a new crankset but I don't know how to find out of a crankset is compatible with my bike. My bike is a trek 930 and it has shimano stx cranks on it.

Im wondering if this crankset would fit on my bike

https://wheelworld.com/site/itemdetai...=39&sort=Price

My other question is, why is that xt crank 99 dollars and the other ones they are selling are 250?
Whats the difference between all the different xt cranks, and how do i find out what crank will fit on my bike?

does the one thats 99 not include the other crank arm or something? will i need to buy a compatible bottom bracket?

EJ123

Hey I have the same size as that crank on my bike

Pheard

also which bottom bracket would go with my crankset?

https://wheelworld.com/site/showitem....ory&Catalog=39

Pheard

Im surprised the ****** who makes a topic about pineapples gets more replies than this topic which actually is about a valid thing to do with mtbing.

EJ123

Haha yeah really

harov3

If Im correct(not often) then stx is old time shimano long gone and has a taper fit or square bottom bracket to crank fit. In which case no that xt wont fit as it has an octalink type crankarm fit. Get someone whos knows to confirm the type of BB you have and if it is square you could cruise ebay for square or taper fit crankarms. Or try pricepoint.

Yeah, pineapples belongs in Foo.


Ebay

Raiyn

It will fit, just not on your BB
Because thats a 752 and they're in the 760 series now
New model more refined design etc etc
It says "cranks" not "crank" so one could safely say they mean both arms

Pheard

RAIYN THANK YOU, you are the single most valuable information source on this site.

also, will any of the xt bbs work with that crank? or is there a specific one, if so link me to which one.

Raiyn

I don't know your BB shell size. It's either a 68 or a 72.

Pheard

how do I figure it out? is there a way to see what size a trek 930 shell size is online?

Raiyn

It's likely a 68, but aside from contacting Trek (or getting lucky here) your best bet is to see what your current one is when you yank it. Don't just take my guess for a fact on this one

Pheard

Ok, so basically I need to pull my crank. Problem is I don't know how to use my crank puller. But, you've been an amazing help raiyn.

also, they have 68x107,110,113... so on.. my bb will say exactly what dimensions I assume?

Raiyn

You have to do more than that, you have to pull out the BB as well.
Crank removal
https://www.parktool.com/repair/readhowto.asp?id=103
Bottom bracket removal
https://www.parktool.com/repair/readhowto.asp?id=94

You can't go by the old one for the axle length (113,118 etc) your NEW cranks will dictate that and I don't have a Shimano manual sitting in front of me.

Pheard

You can't go by the old one for the axle length (113,118 etc) your NEW cranks will dictate that and I don't have a Shimano manual sitting in front of me.


Im confused what do you mean?

edit: nvm I see what your saying my bike dictates the first number the second one depends on the crank I buy

mtb-chop

Crank puller - remove the crank bolt, thread the outer part of the crank puller into the crank arm (probably be able to do this without a wrench), and turn the handle part of the crank puller until you feel the crank puller post contact the bottom bracket spindle. Resistance at first will likely be pretty high, but turn the handle until you unseat the crank arm. A couple of turns past that, the crankarm should come right off. Then just unthread the puller from the crankarm and you're done.

Cranks and bottom brackets are fun - enjoy!!

Then you need to get the bottom bracket out - start on the non-drive side and then the drive side. After you get it out, you should see the size in the middle of the bb.

Raiyn

Let's see, spend $150 on a new crankset and BB or spend $15 to replace the current one? I'd rather spend the $15 and get the thing back up and running so I can save $$$ for the next bike.
Besides that it's damn hard for me to accurately diagnose a bike over the internet. Take it to the shop and see what they say. If the cranks are f'd then upgrade if you want, but if they're still good to go then ride them into the ground

Pheard

Ok, thx for the advice raiyn. Im going to bring to the shop, if the crank is screwed ill get the xt setup. My last question is how do I figure out what size im going to need to get for the xt crank? (i mean for the second number)

The only reason Im thinking about getting the xt crank even if my crank aint screwed up is its a great price for an xt crank. My crank as it is has tons of teeth that are bent and starting to come off.

Raiyn

It's either going to be the 113 or the 118. Seeing as this is a steel bike with narrower tubing I'm going to make an educated guess and say the 113
You do know that you can replace chain rings too right? You don't have to replace the whole bloody thing.

Pheard

Yea I know, but I mean better crank I can use when I DO get a new bike. If I got a new bike I would have to get a different size bb assuming I do get this xt crank though right?

Raiyn

Possible. You may need to get the 118, but that depends on the bike in question. Basically what you're doing is trying to make the chainline as close to perfect as possible. Now the 118 is only 2.5mm wider per side, but that can make a difference when adjusting and using certain gear combos, not to mention drivetrain life. Nine speed systems are a lot more finicky than your current 7 or 8 speed system when it comes to such things.

Pheard

Well I went to the bike shop and the bb is completely bent in one direction. The guy said all I need to replace is the bb but I asked if he would suggest me just getting a new crank (my old one is in crap shape anyways). So Ive ordered the xt and the bb for it.


My last question is all the cranks have sizes 160mm, 170mm, 175mm, 180mm
what is that a measurement of? the crank arm length or what? the crank im buying only comes in 175mm does this measurement matter compatibility-wise? or is it just a preference when it comes to the bike.

Raiyn

Which is what I told you.
Everything you ever wanted to know about cranks, but were afraid to ask
https://www.sheldonbrown.com/cranks.html

Pheard

how do I see what size my old stx crank was?

Raiyn

Should be stamped on the inside of the arm

Pheard

yep, turns out I ordered the same size.