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 Post subject: Bottom brackets
PostPosted: Wed Oct 03, 2012 2:26 pm 
Dirt Disciple

Joined: Wed Aug 22, 2012 1:01 pm
Posts: 38
Query -
I have an old Kona Lana'i (2001/2002 I think) which used, as standard, a 68mm shell bottom bracket of the non-cartridge kind. A loose bearing cup and cone thing. A standard that I didn't realise even existed up until I had one in my hand.

Now, it is deal, and there is no resurrecting it. I have tried a cartridge one in there, and it screws in fine. The one I have (110mm axle) is too short. The chainrings are about 5-6mm too close (which makes sense, given that I've shortened the axle by about 12mm). So by my reckoning, if I can find something around the 122mm length, I should be fine. Which I can.

BUT, Uncle Sheldon seems to suggest that I need something more akin to 130mm in length. Is he talking about something much old than what I have? Is there some really old standard of which I know nothing because, not only was I not riding bikes, but I wasn't even breathing when it was last used? Have I actually got a symmetrical cartridge bottom bracket (for all intents and purposes), but with crappy ball bearings? So should I be looking for something that really is about 122mm in length?

Thanks


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 Post subject:
PostPosted: Wed Oct 03, 2012 2:28 pm 
MacRetro rider
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Joined: Sat May 22, 2010 7:25 pm
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Location: Edinburgh
It all depends on the cranks you have on it. What are they?


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 Post subject:
PostPosted: Wed Oct 03, 2012 2:30 pm 
Dirt Disciple

Joined: Wed Aug 22, 2012 1:01 pm
Posts: 38
Ah, the one thing I have forgotten. Its the standard Shimano square taper cranks. Actually, they're Suntour, but they use the standard Shimano square taper.


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 Post subject:
PostPosted: Wed Oct 03, 2012 2:43 pm 
BoTM Winner
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Joined: Thu Jan 19, 2006 1:23 pm
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Location: NW England
If you've got the cranks installed with the 110mm bottom bracket then measure from the centre of the BB* to the centre of the middle chainring ring (horizontally). This measurement should be 47.5 for optimum chainline so calculate what length BB you will need to space the chainset out to be this measurement.

*I find it easier to measure from the end of the BB shell and subtract 34.


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 Post subject:
PostPosted: Wed Oct 03, 2012 6:06 pm 
retrobike rider
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Joined: Fri Aug 08, 2008 2:36 pm
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Location: Yorkshire, England
Just knowing Suntour or Shimano means little really.
The design of the crank dictates what length bottom bracket you should be using as they vary in profile*. So a model number is what is needed to give a more definite answer.


*profile, the position of the taper hole compared to the rings, see picture I put up some time ago
Image


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 Post subject:
PostPosted: Wed Oct 03, 2012 6:12 pm 
retrobike rider
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Joined: Fri Aug 08, 2008 2:36 pm
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Location: Yorkshire, England
Hang on, you have the old bottom bracket... just measure it.
Also if it's that much too short and not jammed right into the frame bending the rings then it's probably around the correct length.
( as if it was that much too short from 122, it'll be hitting the frame)

If there is <10mm at the chainstay with the arm and they are not touching, the job should be a goodun'

Only retro Suntour would be using the 122mm+ lengths I would have thought.
Modern stuff will be in the 107 to 118 region.


---
EDIT
If it's the original chainset then it's a Sun Race FC-M55 chainset if it is original, and the 2002 bike (no 2001 bike)
It would have had a VP cartridge bottom bracket in it so the cup/cone is a bodge sometime after (probably)

If it is SunRace you could email them, the FC-M52 and similar level do use 122mm bottom brackets and the is now, no reason the old M55 didn't then.
http://www.sunrace.com/userfiles/products/specs/FCM.pdf

--
EDIT2
Nope 110mm should be the 'stock' length or so say Kona in the Tech docs (in the Archive)

(cut/paste)
The Kona Hula is a 24" bike with plenty of performance for the young ridesr.
Built around an excellent frame with a lightweight parts package.
TOP TUBE
Ø 31.8 x 1.8t
Round 6061

DOWN TUBE
Ø 38 x 1.8t
Round 6061

SEAT TUBE
Ø 31.8 x 2.3t
Round 6061

HEAD TUBE
Ø 41 * Ø 33.95
Forged 6061

SEAT STAYS
Ø 19 x 1.8t
Round 6061

CHAIN STAYS
Ø 22.2 x 1.8t
Round 6061

RR HANGER
Seat Post
27.0

Bottom Bracket
68 x 110mm

Headset
1-1/8"

· 6061 aluminum tubing. Forged bottom bracket and head tube
· Forged dropouts with replaceable derailleur hanger (type H)
· Complete bike weighs 26.9 lbs


Last edited by FluffyChicken on Wed Oct 03, 2012 6:29 pm, edited 1 time in total.

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 Post subject:
PostPosted: Wed Oct 03, 2012 6:27 pm 
retrobike rider
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Location: Yorkshire, England
If it's a 2003 then it had a suntour chainset Suntour CW-XCC, 22/32/42 teeth confirm the year first....
you can look up the tech docs and info on 1993 Kona's in the Archive but it'll be 110 ;)
..


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 Post subject:
PostPosted: Wed Oct 03, 2012 6:33 pm 
Dirt Disciple

Joined: Wed Aug 22, 2012 1:01 pm
Posts: 38
My measurements suggest something in the region of 118 to 12mm. Thanks.


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