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Drivetrain woes (external bearing bb at work again)

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BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
So yeah, Ive been tooling with the shifting for weeks, and Ive got it about right except that gears 1 and 2 on the back slip down when I pedal backward in my biggest front ring (32). Ive tweaked everything I can, and still cant make it work. The chainline is just funky.
So to be sure, I took it to the LBS (gasp!) and they poked at it for a few minutes and agreed with me. WTF? So I just have to accept that it wont ever work right?
Basically, there are three spacers with the BB, one on the drive side, however if I remove it, my front Der. wont function.
This sucks.
 
J

JRB

Guest
I am about to leave, but post pics and peeps will be able to help I am sure. Chainline is the one thing I think is whacky about the new BB types. I had to run spacers on the non-drive, like you said. I don't remember having 3 though. Hell - I don't recall without looking. What derailler is it??? I had a bike that I couldn't run XTR on, but XT worked fine.
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
Der. is an x7.

Hone front der.

Still, Im pretty sure neither of those are a factor, unless there is a front der. out there that somehow bottoms out much closer to the frame than the one i have. Spacers on the non-drive side wont matter, obviously, but the ONE on the drive side is necessary to provide enough spacing for the front der. to work. I dunno. Sucks tho.
 
Wumpus

Wumpus

makes avatars better
Dec 25, 2003
8,161
153
Six Shooter Junction
BurlyShirley said:
unless there is a front der. out there that somehow bottoms out much closer to the frame than the one i have. Spacers on the non-drive side wont matter, obviously, but the ONE on the drive side is necessary to provide enough spacing for the front der. to work. I dunno. Sucks tho.
Click to expand...
Maybe a road front derailer???


I know nothing about SCAM derailers, but is there some kind of B-screw. Maybe the top pulley is too close to the cogs.
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
Wumpus said:
Maybe a road front derailer???


I know nothing about SCAM derailers, but is there some kind of B-screw. Maybe the top pulley is too close to the cogs.
Click to expand...
Its a shimano hone der. pay attention:rofl:
 
def

def

Monkey
Feb 12, 2003
520
0
knoxville, tn
Mine does the same thing in the 34 and 31 too if I back pedal more than a full revolution. (XT external crank, old ass XT rear der and red carrier sram gears) I've just gotten used to it and don't back pedal more than I need to, you pedal foreward to get up the hills. I haven't messed w/ the spacers because I just don't want my non drive crank arm to be any further out than it is. But I do believe the issue is the spacing behind the bb.


edit: just read your post again. 3 spacers on the drive side?! I've got....let me look.....2 drive/1 non drive. I say kick one over to the non drive and readjust your der. A little english and patience should make that derailuer work.
 
Wumpus

Wumpus

makes avatars better
Dec 25, 2003
8,161
153
Six Shooter Junction
Make sure you don't have a bent rear cog or a bent tooth. I had a bent tooth that was causing the chain to jump when I backpedalled.


You're chainline might be bad, but it can't be worse than the one on my Banshee and I don't have any issues (121mm spindle with XT cranks - 52ish mm chainline). Recommended chainline for MTB is around 47.5-50mm front chainline -- Measured from center of seattube to middle ring.
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
d.e.f. said:
Mine does the same thing in the 34 and 31 too if I back pedal more than a full revolution. (XT external crank, old ass XT rear der and red carrier sram gears) I've just gotten used to it and don't back pedal more than I need to, you pedal foreward to get up the hills. I haven't messed w/ the spacers because I just don't want my non drive crank arm to be any further out than it is. But I do believe the issue is the spacing behind the bb.


edit: just read your post again. 3 spacers on the drive side?! I've got....let me look.....2 drive/1 non drive. I say kick one over to the non drive and readjust your der. A little english and patience should make that derailuer work.
Click to expand...
No. I have ONE spacer on the drive side TWO on the non drive side. I cant go any less than that.
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
Wumpus said:
Make sure you don't have a bent rear cog or a bent tooth. I had a bent tooth that was causing the chain to jump when I backpedalled.


You're chainline might be bad, but it can't be worse than the one on my Banshee and I don't have any issues (121mm spindle with XT cranks - 52ish mm chainline). Recommended chainline for MTB is around 47.5-50mm front chainline -- Measured from center of seattube to middle ring.
Click to expand...
Ive checked the teeth and no bends. I had that issue before, so it was one of the first things I check out. With what you say about the Banshee though, it does seem odd that I cant get it right.
 
A

auntesther

Monkey
Oct 15, 2001
293
0
Boston, MA
I have Hone cranks on my Giant Reign and I have just accepted the chainline isnt going to be great. I played with the spacers..or I should say I began to..but the nondrive side has such few threads, I did not feel comfortable running 2 spacers on tha side. One thing you could do is get a RaceFace Diablous BB...they have deeper cups and thus alot more threads..so you could probably shift the spacers around alot more with those cups and maybe get the chainline back in decent order. With the stock Shimano BB, its just not gonna be great. I did have a bit better luck with a SRAM chain and adding a couple of links so the chain wasnt so tight in the bigger cogs
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
johnbryanpeters said:
Did you happen to read the instructions? They're very specific about how many spacers to use and on what side, depending on width of bottom bracket and type of front derailleur. Required number of spacers can range from zero to three.
Click to expand...
Yes, of course.
 
def

def

Monkey
Feb 12, 2003
520
0
knoxville, tn
BurlyShirley said:
No. I have ONE spacer on the drive side TWO on the non drive side. I cant go any less than that.
Click to expand...
Gottcha. I read it, but for some reason, not too closely. I'm known to be a retard from time to time.


Will the front der hit the chain rings when you shift? Or does the no spacer routine put the crank so close that even w/ the lower limit all the way out, it hits the frame and limits shifting? I know the set up gods will be mad, but you could maybe raise the front der up a little higher (but not too much) than normal to clear the rings better <- if its hitting the chain rings and you can't fool too much w/ the limit screws.
Also......is the rear end in alignment? Even if its slightly off a few mm's, it can make a big difference. I'm sure mike didn't do much w/ it, but he isn't a 125lb teenager.

Online diagnosis and trouble shooting is almost as difficult as the phone call at midnight from a buddy getting ready for the next day's ride. Good luck w/ it.
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
Yeah, If I remove that spacer, the der. will hit the chainrings. I dont think that I could move it up enough without terribly screwing it all up. I will give that another shot tomorrow though and see how it goes.
I havent given much thought to the rear not being squared up, but that could explain it.
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
johnbryanpeters said:
What led you to two spacers on the non-drive side and one on the drive side as opposed to the opposite (I'm presuming 68 mm BB and clamp-type derailleur)?
Click to expand...
The instructions, actually. Another spacer on the drive side would make the chainline that much worse.
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
johnbryanpeters said:
I must have misread the instructions. I thought that for a 68mm bracket it showed two on the drive side and one on the opposite.
Click to expand...
It definitely didnt say that on the instructions I got with the crankset, although I didnt really look at what you posted. But as I said, either way, another spacer would really screw things up.
 
DirtyMike

DirtyMike

Turbo Fluffer
Aug 8, 2005
14,437
1,017
My own world inside my head
BurlyShirley said:
Yeah, If I remove that spacer, the der. will hit the chainrings. I dont think that I could move it up enough without terribly screwing it all up. I will give that another shot tomorrow though and see how it goes.
I havent given much thought to the rear not being squared up, but that could explain it.
Click to expand...

I have ran into this directly with the Bullit and a set of XT cranks. 1 drive side two none drive is for a 68mm shell, for a 73 youll need only two, Now as for were your Derailer is hitting, to realy make this work well your going to want 2 spacers on teh Nondrive side, and an Etype derailer on the drive side. Should still be available in an XT!!! That will fix you right up!!!!
 
BurlyShirley

BurlyShirley

Rex Grossman Will Rise Again
Jul 4, 2002
19,180
17
TN
DirtyMike said:
I have ran into this directly with the Bullit and a set of XT cranks. 1 drive side two none drive is for a 68mm shell, for a 73 youll need only two, Now as for were your Derailer is hitting, to realy make this work well your going to want 2 spacers on teh Nondrive side, and an Etype derailer on the drive side. Should still be available in an XT!!! That will fix you right up!!!!
Click to expand...
The bullit I have is a 68mm shell. But I will surely look into the e-type thing. Its not the answer Id like, but it may have to do.
 
DirtyMike

DirtyMike

Turbo Fluffer
Aug 8, 2005
14,437
1,017
My own world inside my head
Naw, if you can get a hold of one of the XT etypes they perform just fine. The XTR's on the other hand, are the SUCK!!! the carbon is Way to flexy to work very well. Should be ok with two spacers on Nondrive side and an etype derailer, just make sure when you sinch up that the bearing cups bottom on the frame, not on the tube that goes in between and youll be set
 
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