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Texan
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Tools are easy, knowing what your doing takes a lot of time and dedication. Google Sheldon Brown and Park Tools, and buy the book Zen and the art of bicycle maintenance.
 

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What kind of cranks do you have?

Those are two different tool - each one is for a different crank style.

park tools website has good tutorials. Its pretty easy to take off a crank, you have
to be careful to not over or under tighten when installing.

Remember, no right tight lefty loosey on cranks or pedals. If you have your tool at a 12 o clock position it always loosens towards the rear of the bike.

You also need grease and a way to clean out the threads.
 

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I'm being lazy and not researching your cranks...you can do that. Plus, I wouldn't know if your current cranks/bb are stock or not... they could have switched out to something else.

Your crank/bb type will determine the tools that are needed.

For a 2007, it could be one of 3 different types...square taper bb, isis/octalink, or external bb.

I'm gonna guess it's square taper.

For each type, different tools will be required to a) remove the crank and b) remove the bb.

As mentioned, the cups will not be threaded typical lefty loosey, righty tighty...one will, but the other will be opposite...I'm sick and forget at the moment which is which. Same thing with removing the pedals.

So, determine which crank/bb type you have and get the right tools. A good way to also learn is to take it to a shop where they can show you what you have, explain the differences between the 3 major types and then show you the appropriate tool that you can buy from them. Everyone wins.
 

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Hi guys/gals, I'm "new" to this forum and have to find my way around. VERY SIMILAR though to the metal detecting forum that I'm used to so there is a plus there. Anyways, didn't know how else to post/new thread because it says I need at least 5. In either case, this is the perfect start as I have similar questions about the BB/spindle and all. I just bought a '11 GT Avalanche 3.0 (black) and am new to MT'bking. I know it's "cheap" bottom of the barrel bike. I've done my fair share of road biking in the past when I was MUCH YOUNGER, but have "grown" out of it and was NEVER able to get back into it. So I decided to finally buy a MT bike. A very VERY DIFFERENT feeling when it comes to steering compared to a road bike. Anyways, this is the perfect thread to start reading/posting. Sorry to the "OP" for "hijacking" the thread in introducing myself. This is NOT my intentions. Like I said, "I have questions myself..." on the subject at hand. Anyhow, nice to "meet" all of you.
 

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First off, welcome back to biking and to the forum EatingDirt! The GT is actually a great start in the addictive world that is mountain baking.. definitely a lot different than road biking and MTBR is an awesome community in which to ask questions and share your experiences. Don't hesitate to ask a related question here until you can create your own thread!

zero_cooljr, I second will-lee wonka's suggestion.. If you can't get to a LBS do as driven instructed and post a picture - makes it much easier to help diagnose.
 

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thank you drblauston for the welcome. My question relates to this thread in that I was wondering what "size" BB I have. I will go back to the LBS "Performance" and ask, but I kinda already did. I asked him that I wanted to know if it was a 68x110 or ? Was I right about this question? I mean, I barely knew 170 or 175 for the crank size? Anyways, I won't go off subject too much. I had also asked if I could have the "build" sheets or bike parts list that the bike came with (they put the bike together for me) and he basically said, "the bike comes with so many different options that there really is no parts list..." Finally, what I meant by parts list is this:
1x front derailuer
2x washers
6x bolts

if you get what I mean. For example, (hopefully a better example) what kind of a BB did my bike come with? Is it a UN54 and what size? Was it a 68x110 or a 68x113 etc (without taking the thing apart and especially now, since it is brand new)? I also asked, are the cranks JIS or ISO? I know, from reading this forum that there is a fairly big difference between the two and don't want to mix and match. How do I find out what I have is basically the question that I have? I have MANY questions to ask. I am by NO means a "hard core" MT'bker. I don't plan on jumping off of 10ft roofs or "bunny hopping" from one rock to the next on the edge of a 100+ foot drop off. HOWEVER, I do miss the days of being able to go "off road" if I want to and just, OBVIOUSLY, was never able to do that with the road bikes. I think that was one thing that got me back into the "dirt". As far as I'm concerned, too old to do a "superman" over the bars nowadays. Anyways, I plan on going back to the LBS sometime this week and asking the same and/or similar question. ALSO, when I stand on my bike, is it supposed to basically... well... without getting too graphical, is it supposed to basically "touch" the croch area, but yet be able to stand "flat footed"? That is how it is with mine. I know for a road bike that there is supposed to be a "little bit of space" when standing over the "top tube". Is it somewhat different when being fitted for a MT bike? I mean, he did "fit" me, but it just seems a bit weird and/or I'm just NOT used to it because it IS a MT bike and they are pretty different in MANY ways compared to a road bike. Sorry if it is somewhat off subject, but again as you can see, I have some questions. I eventually hope to pass on my experiences to the next person after I read and learn some more off of this forum and my riding experiences. Again, thank you for the welcome!!!
 

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EatingDirt, the recommended stand over height is 2 to 4 inches. My bike gives me 1.5 inches.

Here is one way to check. Stand over the bike, pull it up by the top bar and seat until it is against your body and also level (both wheels the same distance off the ground or floor). Do you have about 2 inches, or more, under the tires? Aggressive riding styles require the generous stand over height.

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zero_cooljr, Gary H gave you good advice. The book "Zen and the Art of Bicycle Maintenance" is about $17.00 at amazon and is money well spent for anyone that owns a mountain bike.
 

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EatingDirt, the recommended stand over height is 2 to 4 inches. My bike gives me 1.5 inches.

Here is one way to check. Stand over the bike, pull it up by the top bar and seat until it is against your body and also level (both wheels the same distance off the ground or floor). Do you have about 2 inches, or more, under the tires? Aggressive riding styles require the generous stand over height.

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zero_cooljr, Gary H gave you good advice. The book "Zen and the Art of Bicycle Maintenance" is about $17.00 at amazon and is money well spent for anyone that owns a mountain bike.
Jim Holloman, do I "compress" the front shock all the way and then lock it out? Then try the "stand over"? I can see that the front fork w/ shock would make the bike "taller" than normal. Again, compared to a road bike, MT bikes are different in certain aspects. Thank you for the book title as well. Will be looking for this book as well.
 

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So I was wondering if those will do the trick, or if I'll need other tools.
I don't know what BB is on that bike as you didn't specify what model level it is. You're probably running a Hollowtech or ISIS style splined crank instead of an external BB system so I would suggest this tool:
https://www.amazon.com/Pedros-Unive...=sporting-goods&ie=UTF8&qid=1325690996&sr=1-1
It has adapters so it can pull square taper or round cranks and it has the 8mm wrench needed to pull most crank fixing bolts.

If your BB is external then it looks something like this:

Where your frame (yellow) is surrounded on both sides by large cups (black) with notches evenly spaced around the edges for removal. That will require the BBT-9C for removal.

As for the BB, you'll need something like this:
Amazon.com: Pedro's Bottom Bracket Socket - ISIS Compatible: Sports & Outdoors
ISIS compatible means that it should worth with most internally splined BBs that you will come across.
 

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Jim Holloman, do I "compress" the front shock all the way and then lock it out? Then try the "stand over"? I can see that the front fork w/ shock would make the bike "taller" than normal. Again, compared to a road bike, MT bikes are different in certain aspects. Thank you for the book title as well. Will be looking for this book as well.
No, don't compress the shock to get your stand over.

Now, your boys may touch the top tube, depending on how you hang ;-)...but the clearance is really to your crotch. I.E.--stand over the bike and lift it off the ground to where you can't lift anymore...right up against your groin (not to the point of pain, of course)...lifting the bike evenly, the tires should come off the ground a few inches (equally since bike is level). Jim Holloman described the same technique.

The size of the BB is important, but less so than the type.

The shop doesn't sound like they are being much help, to be honest. A new/stock Avalanche 3.0 is going to come equipped the same whether you buy it from Performance in Alaska or Bob's Bike Shop in Florida.

I'm assuming you have the disc version?
2011 GT Avalanche 3.0 Disc Mountain Bike - Mountain Bikes

There's a link under Specs for the parts listing, although it's not the best listing.

From googling the crankset, it appears it comes with a square taper bottom bracket.

Good luck and have fun riding!
 

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Fat-tired Roadie
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This thread is making my head hurt a little bit. ;)

Part of the problem is that there are several different standards and sizes involved.

I don't want to restate too much of #17, because he covers the types pretty well. Don't worry about ISO vs. JIS. ISO is some European road cranks and bottom brackets, and you'd have to go out of your way to get one. As zebrahum suggests, you probably don't even have square taper anyway. As others have suggested, you're usually best off just pulling off one of the crank arms to figure out what you've got, and removing the bottom bracket to figure out its spindle length.

The bicycle itself almost certainly has a 68mm English-threaded bottom bracket shell. That means that you need a bottom bracket for a 68mm shell. The crank determines the required spindle length. Unless you have a specific reason to change, just getting a one-for-one replacement is the way to go if you've killed your bottom bracket. It's about a $30 part, your shop most likely has it in stock, and getting it swapped costs about the same as the tool. For a while, mountain bikes were pretty consistent about having either this type of shell or a similar but slightly wider one. Now there are a couple of standards out there, so you can't just buy a bottom bracket and expect it to work - you need to know what you're replacing, or understand what your particular crank and shell need.

So what's the goal here? Personally, I wouldn't bother buying tools for this task unless I expected to use them again, and if you're changing to a different style of bottom bracket, that's at least one set you won't be reusing.
 

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For example, (hopefully a better example) what kind of a BB did my bike come with? Is it a UN54 and what size? Was it a 68x110 or a 68x113 etc (without taking the thing apart and especially now, since it is brand new)? I also asked, are the cranks JIS or ISO? I know, from reading this forum that there is a fairly big difference between the two and don't want to mix and match. How do I find out what I have is basically the question that I have?
The best place to get a "parts list" for your bike is the manufacturer's web site. For your bike, here is the spec list:
http://www.gtbicycles.com/2012/bikes/mountain/trail/2012-avalanche-3-0

For all intents and purposes, unless something breaks, you don't need to know a lot of the specific details. For your example of BBs, who cares what size it is unless you need to replace it. When it wears out, then worry about it.
 

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laffeaux, AndrwSwitch, and the rest... thank you. Sorry that I'm such a new guy at this. Point is well taken as far as, "until the part breaks..." Let me just share a quick background about me, I build my own computers (i.e. buy the motherboard, mem, HDD, etc etc etc) because back in the day I was sold a computer by a salesman that told me ALL kinds of things I could do with it... LONG STORY SHORT, I found out that you couldn't do squat with it, thus, over 25yrs later (i.e. present day) I've tried to do things myself as much as possible. Hence the reason I joined this forum, so I can learn. I don't mean to bother with dumb questions... just trying to learn what I've read and my own past experiences with road bikes. MT bikes are, I'm sorry, a "whole new world"... at least to me!!! Of course, there ARE similarities, BUT... well, I'll just leave it at that... so THAT is a basic background of me. Thank you for sharing your thoughts and experiences and I... eventually... plan on passing it along to the next person. I do have ONE last question however, please humble me for this one... how DO YOU KNOW and/or why are the BB's vary? 68x110... 68x113 etc? Is it because of the "chain line" and some frames are just "wider" in the back than others? 3mm is THAT crucial??? Just asking. Again, thank you guys. Onto the next thread to read and learn after this one.
 

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Fat-tired Roadie
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Usually the crankset specifies the bottom bracket spindle length for a given shell width. And, it's arbitrary. Just how the designer decided to put the taper in the crank arms.

One might choose to use a spindle length other than the one recommended. Tuning chainline would be the most common reason.

The vast majority of mountain bikes have 135mm spacing in the back, and the distance from center for the cassette is standard. There are exceptions, of course. Unlike computers, which were developed by engineers (who thought the other engineers were idiots and developed competing standards...) bicycles evolved. There are competing standards that are the result of parallel development processes, intellectual property stuff, and sometimes just one company deciding they have a better idea.

Think of the frame of the bike as being a lot like a CPU housing/power supply set. It dictates what motherboards are compatible, at least without modification, what drive form factors are compatible, how much power is available without modification, etc. In this metaphor, the crank is kind of like the motherboard. While you get some choice as to which chain rings and bottom brackets you can use, they have to be compatible with both the frame and the crank arms.

Check out sheldonbrown.com for a lot of historical information. His site is a brilliant resource if you want to get a little deeper into the why.

And like I said earlier - how I'd know what bottom bracket I had/needed would be to either pull it out and look at it, pull the crank arms off and measure the spindle, or look it up in the manual or specification for the crank, depending on the circumstances.

3mm can be pretty important, but it's not necessarily. Some frames have very tight clearance around the chain rings, especially if you're using larger chain rings than what the designer had in mind. So, 1.5mm can be the difference between clearing the chainstay and taking little chunks out of it when you get out of the saddle and hammer.

Aside from suspension components, really a mountain bike is mechanically near-identical to a road bike. Some things are sized or shaped differently, but it's got all the same parts and many of them are cross-compatible.
 

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A. Don't be sorry for asking questions, that's what the forum is for. Sometimes you'll get good answers...sometimes you wont. Hopefully, the law of averages will work in your favor. ;-)

2. How do you know what size the BB is? You pull it out of the frame. That's the only way to be sure about what is in there. The size will be stated on the BB itself. And if it's been worn off or doesn't say, it can be measured. Now, how do you know what's SUPPOSED to be in there? You might have to scrounge up some specs online or if the bike is new and stock then you'll know when you pull the old one out.

D. Switching sizes of BB can affect the drivetrain. It can throw off the intended chainline, as meant by the frame designers (as Andrw stated...including the reason for the different lengths). And if you get a BB length that is shorter than intended, you may have rubbing of the chainrings on the frame, which as you can imagine would be bad (Andrw covered that too ;-)).

However, note that newer external BB/cranks spindles come in one size so you don't have the ability to choose your spindle length like with traditional cartidge BBs. So, that can maybe put your mind at ease some about choosing the exact correct BB size. Don't stress too much about the size. Get the correct shell size and try to match the spindle length to what you have or maybe get it close...and if you get a newer external bb/crankset, then you don't have to think about it at all as it's one size fits all (for better or worse).
 

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2. How do you know what size the BB is?
Just to add on to this post, you can also measure it in the frame. Measure the width of the BB shell (where the BB threads in to) and if you pull the cranks you can put a pair of calipers on the BB spindle as well. Measurements are in millimeters.
 

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I LOVE this PLACE!!!:thumbsup: The people here are "down to earth". I was afraid at first to even sign up because in my past experiences with road biking... well, let me just say that people nowadays "act" like they're wearing "the yellow jersey". I'm sorry, but I just can't personally get into that kinda "mindset" thinking that I'm better than the next guy. As far as I'm concerned, you bleed just as bad as I do and I do NOT have something to prove to myself or others THAT BAD!!! That only says that you have some sort of self confidence issue and I HAD to get away from that. Anyways, IMHO, a bunch of "pricks" are out on the road these days. Just relax and ride... life is tooo short to "pass" by. BTW, did I say that I NJOY this place. Thank you all for the welcome and advice. It is well taken on my end. Now onto the next post/thread to learn about my "new" enjoyment/hobby!!! You guys rock:thumbsup:
 
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