elmore leonard

Trek 820 mountain bike bottom bracket.
I have a blue matte Trek 820 mountain bike. Not sure what year but possibly 2009 with a Suntour crank. Anyone know what bottom bracket I should order?
Thanks in advance, Elmore.

Bill Kapaun

The one that fits your crank.

Andrew R Stewart 

Elmore- Bill's reply is much what I would have said. You are the one with the answers, your bike already has the Bb size in it. That you don't ether know this (that your answer is there) or are unwilling to do some effort to find out which size BB your bike has is too bad. That you don't know how to take advice is sad. Now if you had replied with "how do I figure it out" instead of a personal attack on Bill I would have explained how. Andy.

dedhed

Those guys do have 820 experience. Their point is a BB has nothing to do with brand, year, or model of bike. It's all about the crank, spindle length, BB shell width and threading. To know for sure you'll have to pull the old one out and see what it says or measure the spindle length and shell width. It will be english threading

Lanovran

Unbelievable... Someone asks a simple question, and the first thing he gets is a smart-ass reply ("the one that fits your crank" hardly constitutes helpful advice). Then people jump down his throat and behave like condescending jerks when he calls them out on it... Not everything is so cut-and-dry easy for everyone on this forum, guys, because not everyone has the same level of knowledge or experience. We all started somewhere, and we all need help sometimes, so get off your frickin' high horses and keep your rotten attitudes to yourselves.

Now then, in answer to the OP's question... What BB you need first depends on what fits in your frame (i.e. BB type/threading & size). Compatibility with the crank is secondary; because after all, if the BB doesn't fit in the frame in the first place, then the crank is moot. Based on the color you mentioned, it sounds like you have a 2007 Trek 820, which uses a square taper sealed cartridge BB, in size 68x122. You should be able to find a replacement for a decent price at your LBS or online. Shimano's UN-55 is pretty solid, with alloy vs. plastic left-hand threads, and it's pretty affordable. Here's a forum thread from another site started by someone who had a similar need (includes pictures).

elmore leonard

Thanks for the reply and the information Lanovran. Appreciate that.

Andrew R Stewart 

Those of us who frequent this forum get a bit tired of people acting like we just sit here wait for the chance to pull some sort of minutia out of our memory banks. Many of us go back a few decades and learned how to learn. Sure we asked our mentors, and when they said for us to do the homework we complained to our self not to their face.

Perhaps Bill was having a bad day and answered Elmore with a good but less then gifted reply. But Elmore's response was really off base. I mean calling out Bill's mom? That's grade school stuff. This is the context I replied to.

Like I already said, a civil reply and I'd have repeated what I've posted to two others in the last couple of months. A reply as to how to measure the BB in question and the factors to be aware of when replacing one. But my ship has sailed here. Andy. (who wonders how many 820s it takes to be experienced.)

Lanovran

No...to be honest, I do agree that Elmore's immediate response was uncalled-for in that regard. I honestly just get so tired of all the useless, smart-ass stuff that people go out of their way to post, however, that I felt annoyed on his behalf. I mean, if one isn't inclined to actually answer a question in a useful way, or offer anything of substance, then why post at all? Yes, Elmore could certainly have responded more maturely, but then Bill didn't have to waste his time with what seemed for all the world like childish & sarcastic trolling, nor resort to calling him an idiotic dolt afterward. I admit that I may have misinterpreted your subsequent remark, Andy, in that I initially read it as another meaningless "too bad, so sad, you're dumb" sort of comment. I apologize if I was unfair in my own response.

As for the actual subject matter, I don't have an encyclopaedic knowledge base of all things 820 (who does?), but I do know where to look for relevant info, and I don't mind taking just a couple of minutes to help out now and then if someone doesn't know where to look. I have asked questions myself in the past that went unanswered because I didn't have the resources to learn on my own, and I only got snark or insults in place of any actual assistance, so I can relate to Elmore feeling frustrated. I do feel that there can be too much elitism and attitude in this forum sometimes, but I will try to do a little better job of keeping level myself.

LesterOfPuppets

The OP has been developing a reputation in here and C&V.

SkyDog75

A square taper bottom bracket needs to be properly sized for the frame and the specific crankset, which is the point Bill was originally trying to make. You can deduce that you'll need a 68 mm English-threaded cartridge because that's what fits the frame, but the required spindle length is dependent on the crankset. If the original poster's cranks are original, he may need a 122 spindle as you said. If he has a different crankset that was designed for a different spindle length, he'll need to measure/verify based on his existing one or look up the crankset (not frame) specs.

Lanovran

Yes, I know. That's why I said the crank is secondary, as in it's the second thing to consider after the frame. A BB could potentially fit the frame, but not the crank, or it could fit the crank, but not the frame. The former circumstance would be easier and cheaper to remedy than the latter, hence my giving priority to frame fit. Of course, ideally, one would be able to find the necessary measurements for both and get it right the first time.

HillRider

Given the cost of square taper cartridge bottom brackets these days I expect making a mistake there would be a lot cheaper to correct than having to change the crank.