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I need to replace my cousins crank... but lost.

mroneeyedboh

mroneeyedboh

Monkey
Oct 16, 2006
106
0
Alright,
My little cousin has a diamondback response bike and its good for him, but the cranks are garbage ( all over the net saying the same ) its a square taper spindle and they come loose and round out the crank arm.

none the less, I'm wondering what or how I can find out the size that is needed to replace the one that is on it. Its a Truvativ x-flow crank. and at this link ( http://www.sram.com/_media/techdocs/2005_cr-4arm-e-r2.pdf ) it looks like there is only one bottom bracket used for that crank ( under square shaft ) but I cannot find any info on the bottom bracket that is installed into the bike.
 
boogenman

boogenman

Turbo Monkey
Nov 3, 2004
4,367
1,041
BUFFALO
save yourself the trouble and go to a shop.

I am sure they can get a isis crank and BB cheap on close-out somewhere.
 
downhillracer

downhillracer

Turbo Monkey
Jan 28, 2005
1,230
0
Sammamish, WA
agreed. isis will be the best bottom bracket/crank combo for the best price that won't round out like the square taper stuff. the bike just prolly wasn't designed or spec-ed to do what he is doing.
 
mroneeyedboh

mroneeyedboh

Monkey
Oct 16, 2006
106
0
I just dont want him to spend much. he wants a new bike but his mother wont let him fork out the money, weird I know.

but Someone has one on here for 75 shipped and that is enough for him, just not sure if it will fit. how do I find out the size, like 68mm or 73mm etc.
 
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slowitdown

Monkey
Mar 30, 2009
553
0
square taper doesn't just "round out" on its own. it happens as a result of not keeping the crank arms snug against the BB spindle, which requires only checking the crank bolts with a torque wrench occasionally -- a very fast thing to do.

square tapers will last much longer than most other designs if you do this. whoever says they just "round out" without any rider/mechanic errors... well, they're just wrong.
 
mroneeyedboh

mroneeyedboh

Monkey
Oct 16, 2006
106
0
haha you mad?

Its not my bike, I take care of mine. Hes young at 10 years old and doesn't get to ride much with me. SO he rides solo or with other YOUNG kids, they don't know of things like that. If it was loose, he would just tighten it. They don't know about torquing..
 
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slowitdown

Monkey
Mar 30, 2009
553
0
mroneeyedboh said:
haha you mad?

Its not my bike, I take care of mine. Hes young at 10 years old and doesn't get to ride much with me. SO he rides solo or with other YOUNG kids, they don't know of things like that. If it was loose, he would just tighten it. They don't know about torquing..
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no man, I just don't want to see you spend $$$ merely because someone told you square tapers always round out.

so I see what happened, it wasn't clear to me from your first post. I know, kids don't think about maintenance or torque wrenches, most of 'em. it's understandable that this one would get loose and round out.

but honestly even more modern ISIS standard cranks can get loose -- Truvativ Stylos in recent years had problems, both with their ISIS and their external BB types. I hear it has something to do with poor interface fit where the crankarm attaches.

you from Baltimore? the Natty Boh dude avatar...
 
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downhillracer

downhillracer

Turbo Monkey
Jan 28, 2005
1,230
0
Sammamish, WA
slowitdown said:
square taper doesn't just "round out" on its own. it happens as a result of not keeping the crank arms snug against the BB spindle, which requires only checking the crank bolts with a torque wrench occasionally -- a very fast thing to do.

square tapers will last much longer than most other designs if you do this. whoever says they just "round out" without any rider/mechanic errors... well, they're just wrong.
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not when your jumping. The interface is not snug enough to take the abuse if the kid is jumping the bike. true loose crank bolts will accelerate the process, but square taper cranks do have flaws. you will not convince many people that square taper is better than isis. Plus a set of ISIS cranks will be better suited for a kid that isn't going to be that keen on tighening or torqueing them for that matter.
 
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mroneeyedboh

mroneeyedboh

Monkey
Oct 16, 2006
106
0
haha alright yeah its for him. and its his money not mine. He wants something better like a banshee hardtail ect. but he cannot get anything too expensive and his mom beefs over stuff like that. so Hes tryin to make do with what he's got. And this frame is fine for him. Hes smaller so it will hold up, for what he needs it to do. He just needs up update the components.
 
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slowitdown

Monkey
Mar 30, 2009
553
0
downhillracer said:
not when your jumping. The interface is not snug enough to take the abuse if the kid is jumping the bike. true loose crank bolts will accelerate the process, but square taper cranks do have flaws. you will not convince many people that square taper is better than isis. Plus a set of ISIS cranks will be better suited for a kid that isn't going to be that keen on tighening or torqueing them for that matter.
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I guess I missed the part where he said the kid is jumping and racing DH.

I guess those people who successfully used sq taper for many years, they don't know what's up.

I guess a small, lighter weight human (a child) has the same sturdiness needs as a fully grown adult who weighs at least 2x more than the child.

Some people just have to be right all the time. :disgust1:
 
mroneeyedboh

mroneeyedboh

Monkey
Oct 16, 2006
106
0
We got the BB out and its not sealed. There was a sleeve inside that says "chin haur" ch-46-2j 113L bc 1.37x24t. Is that 113mm BB? What size crank would fit?
 
ska todd

ska todd

Turbo Monkey
Oct 10, 2001
1,776
0
ahh...the glorious CH46! It's a staple of entry level bikes. They call it a "cartridge style" (ie. it inserts like a cartridge BB but is not sealed). 113mm is the spindle length. I would recommend replacing that BB when you replace the crank. It's not worth keeping that BB if you are needing to replace the crank anyway. You will just be replacing the BB later down the line.

-ska todd
 
mroneeyedboh

mroneeyedboh

Monkey
Oct 16, 2006
106
0
Ok cool. is there any way to figure out the cartridge length? Whats a good cheap ISIS crank/BB to replace it?
 
mroneeyedboh

mroneeyedboh

Monkey
Oct 16, 2006
106
0
slow,
Thanks. I mean I guess it should work, well I mean I thought the same. Just not sure, I'll see if some old heads pop in and put their 2cents in. Not that I dont trust you, more opinions are better than one.
 
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slowitdown

Monkey
Mar 30, 2009
553
0
no worries. I'm just being careful. I don't see any reason why a D'back would have something strange like a BMX no-thread BB shell, but weird stuff happens at the low end of the MTB market so I'm reluctant to say "go spend your money."

if the BB shell on the frame is threaded I'm sure it's going to work.

that Natty Boh dude avatar cracks me up. I used to live in Baltimore and have drank many a Boh and many a Prem at various places.
 
ska todd

ska todd

Turbo Monkey
Oct 10, 2001
1,776
0
w00dy said:
It's a forum, you don't have to sign everything like an email. We know who you are.
I feel like a douche for even typing this, but it bothers me and I had to say something.
Sorry, I'll get a life now.
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ha! Sorry, I can't help it. It's how I've always posted since like day 1 on emptybeer. It's hard to break like eight years of habit.

-ska todd

(oops... ;) )
 
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