Bicycle Mechanics - Looking For BB for This Bike

Thanks to my LBS, i now have a BB in this bike (http://www.trekbikes.com/bikes/2003/mountain/4300.jsp) that is to long. The spindle length is too long and is giving me all sorts of shifting trouble.

If you follow the link i provided to the bike you will see that it has this CRANKSET: Suntour XCC-150 42/34/24. Here is the link to the Suntour Cranks (http://www.srsuntour-cycling.com/servlet/siteos.suntour.SRDownloadServlet?binary_id=430&SID=1096996996_ef93000034c262a85482). It says that i need a 122.5 square taper BB.

Considering the fact that my current problem is that my BB is too wide, doesn't 122.5 seem too wide? (73mm shell) I have read up at Park Tools and Sheldon Brown re: BB install/removal and chainline etc. Do i just take a chance and order the BB suggested by the crank manufacturer?

Does anyone know what BB this 2003, 4300 takes for sure? There are a lot of these bikes out there.

BTW, for those of you wondering....why not take it back to lbs? Well I have told them that i want it replaced and they said they will. I still haven't worked out who pays for what. I figure if i have to pay for anything i may as well do it myself for the experience. The guy also told me, "well the owner really doesn't like to order much this time of year so you can bring it in...it might be 10-14 days until we get the BB in."

Long story short, i really want to do this myself. I have purchased all of the necessary tools and intend on doing most of my own wrenching. I will learn as i go.

I guess they don't like to have you link to a PDF file. Try this link to Suntour (http://www.srsuntour-cycling.com/) instead if it doesn't work for you. Click on chainrings at the top right.

What did they give you?

Thanks to my LBS, i now have a BB in this bike (http://www.trekbikes.com/bikes/2003/mountain/4300.jsp) that is to long. The spindle length is too long and is giving me all sorts of shifting trouble.

If you follow the link i provided to the bike you will see that it has this CRANKSET: Suntour XCC-150 42/34/24. Here is the link to the Suntour Cranks (http://www.srsuntour-cycling.com/servlet/siteos.suntour.SRDownloadServlet?binary_id=430&SID=1096996996_ef93000034c262a85482). It says that i need a 122.5 square taper BB.

Considering the fact that my current problem is that my BB is too wide, doesn't 122.5 seem too wide? (73mm shell) I have read up at Park Tools and Sheldon Brown re: BB install/removal and chainline etc. Do i just take a chance and order the BB suggested by the crank manufacturer?

Does anyone know what BB this 2003, 4300 takes for sure? There are a lot of these bikes out there.

BTW, for those of you wondering....why not take it back to lbs? Well I have told them that i want it replaced and they said they will. I still haven't worked out who pays for what. I figure if i have to pay for anything i may as well do it myself for the experience. The guy also told me, "well the owner really doesn't like to order much this time of year so you can bring it in...it might be 10-14 days until we get the BB in."

Long story short, i really want to do this myself. I have purchased all of the necessary tools and intend on doing most of my own wrenching. I will learn as i go.Have you pulled the cranks and measured the spindle that is in it??? That would seem to be the logical starting point. Who do you think knows best what spindle length their cranks take? I can't believe you are still beating this horse. A 122.5 square taper is a one that shimano offers.. Dollars to donuts, a shimano cartridge removal tool works on it. FWIW, the Sountour site seems broke.....Didn't you say you had another 4300 with the same crank? If so pull the crank and measure that spindle.

Have you pulled the cranks and measured the spindle that is in it??? That would seem to be the logical starting point. Who do you think knows best what spindle length their cranks take? I can't believe you are still beating this horse. A 122.5 square taper is a one that shimano offers.. Dollars to donuts, a shimano cartridge removal tool works on it. FWIW, the Sountour site seems broke.

1. No. i haven't measured the spindle. How can i get accurate measurement without calipers? JUst eyeball it? I am a newbie mech. and really don't want to take it out unti i have a new one.

2. Yes i am still beating this horse. The fact that the chain has started to fall off the inner ring has made me get my stick out again.

3. I too assume that a Shimano removal tool will work. I have one in my garage.

4. The Suntour link is a PDF file on their site. Do you have acrobat reader?

What did they give you?

I don't know the measurement of the one that they gave me. I assume i will need to pull the cranks and measure it. All i know that it is too long and it screws up the front der. The front der. has to be adjusted out too far on the L setting to allow for clearance on the middle and outer rings.

The current setup offers a pretty darned good chainline in any combo using the inner ring. THat includes the outer cog. That tells you right there that it is too wide.

1. No. i haven't measured the spindle. How can i get accurate measurement without calipers? JUst eyeball it? I am a newbie mech. and really don't want to take it out unti i have a new one.

I usually get close enough for govt work with a tape measure or ruler. At least it's a place to start and part of the rational and logical process of problem solving. A caliper is good to have. Even a cheap plastic one is is plenty useful.

I don't know the measurement of the one that they gave me. I assume i will need to pull the cranks and measure it. All i know that it is too long and it screws up the front der. The front der. has to be adjusted out too far on the L setting to allow for clearance on the middle and outer rings.

The current setup offers a pretty darned good chainline in any combo using the inner ring. THat includes the outer cog. That tells you right there that it is too wide.

I love it... the newbie mechanic is an instant expert on chainlines and BB's, but can't figure out how to measure a spindle. :rolleyes: You haven't even measured it yet seem absolutely certain that this one is too wide, and so far I'm looking for any logical reason you would assume that.

You haven't even measured it yet seem absolutely certain that this one is too wide, and so far I'm looking for any logical reason you would assume that.That was hashed and rehashed in another thread.

I love it... the newbie mechanic is an instant expert on chainlines and BB's, but can't figure out how to measure a spindle. :rolleyes: You haven't even measured it yet seem absolutely certain that this one is too wide, and so far I'm looking for any logical reason you would assume that.

Take it easy seely. :p I am no expert at all. That is why I am asking for advice. Which you provided none of BTW. I know the BB is too wide. It has been confirmed by about half a dozen people on this forum in another thread. My LBS also admitted such.

I also do have some mechanical experience. I have been working on electronics and office equipment (mainly copiers) for over 12 years. I can promise you that a copier is a LOT more complicated than a bicycle. It is also very mechanical. In the old days many of them used to be chain driven.

Anyway, i am not going to debate whether or not i am smart enough to diagnose a BB that is too wide. I'll leave that up to you. Until then, if you can tell me what BB this bike takes I would appreciate it. Otherwise you can keep your brilliant observations to yourself. ;)

BTW, how would you measure a spindle that was still mounted in the shell if you didn't have calipers? I knew i could measure it, i just wanted to measure it accurately.




I'm gonna take a W.A.G. and say that if they put a BB in that is too long, It may have caused the front der to reach the outer limit of movement before it reaches the position where there is no rubbing in the big/little combo. By tightening the adjuster screw a little more and then shifting, you place even more force trying to get the der to move when it's already at the limit, which it can't and something has to give. In this case the cable.

You mentioned that they (the LBS) claim the der is at a wierd angle. That reinforces my suspicions that the BB is the wrong size. From the pics it looks to me that the der is at the limit of its travel.

How did it shift before they replaced the BB? .....Trekrider 8/24/04

Original Thread (http://www.bikeforums.net/showthread.php?t=63068)

Anyway, i am not going to debate whether or not i am smart enough to diagnose a BB that is too wide. I'll leave that up to you. Until then, if you can tell me what BB this bike takes I would appreciate it. Otherwise you can keep your brilliant observations to yourself. ;)

BTW, how would you measure a spindle that was still mounted in the shell if you didn't have calipers? I knew i could measure it, i just wanted to measure it accurately.



.....Trekrider 8/24/04

Original Thread (http://www.bikeforums.net/showthread.php?t=63068)
I can measure a BB spindle with a ruler and bloodshot eyeball to about .5mm,and that is more than good enough.The sooner you start actually doing some of this stuff the further down the road you will be.

Well, I learned that a camera actually distorts measurements. :D Look at my pic and it looks like it is under 120mm. In fact the measurement is 127 mm. Therein lies the problem i believe. I am going to order a 122.5 mm and get it fixed.

Thanks for the help. Does anyone know where i can find a 122.5 that is reasonably priced? I have located only one online so far. I don't want to spend too much because i figure the crankset will go bad next week based on my luck.

You might try Bike Tools, Etc. (http://www.biketoolsetc.com/) . They have a wide range of bottom brackets at a wide range of price points.

Doc

sweet spider man ruler!
:D

sweet spider man ruler!
:D

The joys of parenthood. My son has spiderman everything, including bike helmet. :D

I was always under the impression that a spindle length is spec'd based on the crank, not the bike, although there may be a bit of fudge for seat tube diameter (which is usually called out for in the crank manufacturers literature).

Right or wrong, that's the method I've employed. Seems to work for me.

I was always under the impression that a spindle length is spec'd based on the crank, not the bike, although there may be a bit of fudge for seat tube diameter (which is usually called out for in the crank manufacturers literature).

Right or wrong, that's the method I've employed. Seems to work for me.

The 122.5mm that i just ordered is specified by the crank manufacturer. (Suntour)