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got some 3 piece BMX cranks, want to....

Spunger

Git yer dumb questions here
Feb 19, 2003
2,257
0
805
Hey guys, I got some old GT Power series 3 piece cranks off my BMX bike I thought about building up a dirt jumper/urban bike with. The cranks still have the BMX sytle bottom bracket.

I was wondering what I need to do in order to make these work on a dirt jumper/urban bike? The arms are in great shape as well as the bottom bracket. I am assuming I would have to get a new bottom bracket for my mtb bike but I am just wondering what do I need?

Please let me know,
Chris
 

SwisSlesS

Monkey
Jan 31, 2003
385
0
You would need to have a BMX BB shell. I think that's the only way you could use them.
 

pnj

Turbo Monkey till the fat lady sings
Aug 14, 2002
4,696
40
seattle
you need a euro b.b.

you can use the arms and the spindle. you just need the bearings that will fit your frame.

danscomp.com sells them as does albes.com I would bet.
 

Spunger

Git yer dumb questions here
Feb 19, 2003
2,257
0
805
These cranks are like 7-8 year old GT power series cranks. I know my current setup uses a 113mm bottom bracket. I am just wondering, do I just need to get a MTB bottom bracket that accepts those style of 3 piece cranks?

Chris
 

pnj

Turbo Monkey till the fat lady sings
Aug 14, 2002
4,696
40
seattle
7/8 inch spindle, it's round w/ an ass load of splines.

he needs to contact one of the shops i mentioned and they will hook him up
 

sub6

Monkey
Oct 17, 2001
508
0
williamsburg, va
Well, swiss_less is right, you're kinda hosed.

If I remember right, the old Power Pro cranks had their own spline so it's not like you can just use a Profile BB or some such . IF you're very lucky, Dans Comp might have a Euro BB to fit those cranks. I wouldn't count on it. If they're sq.taper just get a UN-72 and you're set, but I doubt that's the case.

Here's a thought. Get a micrometer or dial caliper or some other extremely accurate measuring device. Get a BMX Euro BB, any one - Redline, FSA, Profile, Haro, etc. Measure the outer diameter of the bearings that are in it (take them out of the cups), and also measure their thickness. Then measure the diameter of your spindle that came on the Power Pro cranks.

Go to a bearing supplier and get a pair of bearings that fit those dimensions. Put 'em in the cups, and use your old spindle and cranks.

If you're really lucky, that will work.
 

pnj

Turbo Monkey till the fat lady sings
Aug 14, 2002
4,696
40
seattle
Originally posted by sub6
pnj - do those use a "standard" 48 spline? Or is it an oddball?
I think they use the same spindle as the Profiles. splined.

the cranks I think you are thinking about are the crappy ones that had a square spline. I think they may have had aluminum arms.

I think the cranks he is talking about are just the Profile cranks that GT had made for them.
same cranks, just stamped w/ GT.

I could very well be wrong though. wouldn't be the first time (it'd be the second):)
 

oldschl81

Chimp
Mar 9, 2002
25
0
ridley park.pa
do they look like these?

if so they just use a profile spindle.

if they are the aluminum arms with gt power series written in black email me. i would be interested in trading you a new set for your urban bike or buying them from you.

josh @ oldschl81@hotmail.com


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sub6

Monkey
Oct 17, 2001
508
0
williamsburg, va
yep, oldschool nailed it. Here's the other style - the "square spline" I guess? The spline is hard to see but it's more like an ISIS or an Azonic 454-style spline.
 

Spunger

Git yer dumb questions here
Feb 19, 2003
2,257
0
805
Mine are not square, just round with a ton of smaller splines. Again, they are 1992-1994 GT power series 3 piece cranks. Very burley. I am gonna try and get them off my BMX bike. Nothing is square, all is round.

I'll keep you guys posted,
Chris
 

sub6

Monkey
Oct 17, 2001
508
0
williamsburg, va
Originally posted by Spunger
Mine are not square, just round with a ton of smaller splines. Again, they are 1992-1994 GT power series 3 piece cranks. Very burley. I am gonna try and get them off my BMX bike. Nothing is square, all is round.

I'll keep you guys posted,
Chris
yeah man, that sounds like you have the Profile-made ones. The "square" ones aren't like sq. taper, but more like ISIS splines.

If you go to Dan's Comp you can get the Euro conversion kit for 29.99 and that'll be all ya need, I'm pretty sure those are compatible with Profiles. If you don't want to take the chance then buy the Profile kit but that's more bling.