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PostPosted: Wed Dec 28, 2011 2:24 pm 
Devout Dirtbag
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Joined: Sun Feb 13, 2011 3:48 pm
Posts: 132
Location: Hertfordshire
Hi All,

I have a Beach cruiser with a 1pc crankset and want to convert to a 3pc set. I want to custom my bike and also want the holes where the pedals go to fit 9/16 pedals.

The hole where the set will go through, is that the bottom bracket and if so can I buy pretty much any single speed 3pc crankset or do they come in different diameters?

Sorry for the lame question but I am struggling to get the info I need. I have been looking at MTB sets and there are a few I like but I dont want to buy something if it wont fit. I made the same mistake when I bought my DMR V12 Mag pedals and now I cant use them :-)

Please take pity on a newbie :-)


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PostPosted: Wed Dec 28, 2011 2:44 pm 
Retro Guru
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Joined: Thu Aug 23, 2007 9:19 pm
Posts: 1568
Location: Europa
Things to check:

A. Size of bottom bracket shell (the tube that's part of the bike frame, that holds the BB bearing & crank spindle).

B. The type of spindle needed for your chosen cranks.

C. Possible need for an adapter to fit Spindle type B into frame size A.

If the bikes currently has a 1-piece (Ashtabula) crank, it likely has a large "US" size BMX bottom bracket shell (abut 2 inches diameter and no threads in the frame). It has to be that big to thread the dog-legged 1-piece crank through the frame.

That's good, because it's big enough to fit (almost) any other type crank spindle (possible with an adapter, tho), such as a "Euro" size MTB BB cartridge etc.

Your chosen cranks: Do they use a "square" spindle, or the classic "Profile" type BMX spindle (typically 48 small splines), or something else?

(Almost) All 3-piece cranks will be made for 9/16 pedal spindles to fit your DMRs, whereas you've already found that the 1-pc cranks can have 8/16 pedal threads.

Sheldon is your friend:
http://sheldonbrown.com/bbsize.html#threading

Pics here: BMX size BB shell with an adapter to fit a road/MTB sqare taper BB spindle; later fitted with a Profile BMX crank with a splined BMX axle in "US" BMX size BB bearings (no adapter needed).

http://www.retrobike.co.uk/forum/viewtopic.php?t=86348

Hope that helps for now.


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PostPosted: Wed Dec 28, 2011 2:58 pm 
Devout Dirtbag
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Joined: Sun Feb 13, 2011 3:48 pm
Posts: 132
Location: Hertfordshire
Thats great, thanks a lot, much appreciated.

I would like to do all the work myself, I need to learn sometime I guess but want to avoid too much time and error because that could cost me money by buying the wrong parts.

I will be sure to do my measurements, check out the sites you mentioned and see what I can do.

Thanks again


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PostPosted: Wed Dec 28, 2011 7:28 pm 
Gold Trader / rb Rider / Special
Gold Trader / rb Rider / Special
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Joined: Mon Aug 31, 2009 12:26 am
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Location: Rurally close.
Also dont dmr do a thing called wonder cups? -----

http://www.chainreactioncycles.com/Models.aspx?ModelID=8291


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PostPosted: Wed Dec 28, 2011 9:31 pm 
Retro Guru
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Joined: Wed Apr 21, 2010 8:58 pm
Posts: 359
Location: Cardiff
BMX 3 piece cranks will fit 1 piece BB and still have 9/16 pedal threads!!

You could get a whole crank kit for £50 although it will be heavy!!


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PostPosted: Wed Dec 28, 2011 9:48 pm 
Devout Dirtbag
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Joined: Sun Feb 13, 2011 3:48 pm
Posts: 132
Location: Hertfordshire
Thanks, I dont mind heavy, its a cruiser so I am not too bothered, its not like I need to get anywhere fast :-)

I like this one, MTB one, do you think it will fit?

http://www.tredz.co.uk/.Truvativ-Hussef ... _26232.htm


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PostPosted: Wed Dec 28, 2011 10:08 pm 
Gold Trader / rb Rider / Special
Gold Trader / rb Rider / Special
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Joined: Mon Aug 31, 2009 12:26 am
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Location: Rurally close.
That is a crankset that will fit standard mtb.


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PostPosted: Wed Dec 28, 2011 11:32 pm 
Old School Grand Master
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Joined: Mon Jun 14, 2010 9:06 pm
Posts: 4448
Location: Herts UK
nice one !! 8)

thought I was hallucinating but that Kona logo does spin round :shock: Image


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 Post subject: .
PostPosted: Thu Dec 29, 2011 11:42 am 
aka Leo Swayer
aka Leo Swayer
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Joined: Wed Jun 18, 2008 7:15 pm
Posts: 6365
Location: Wales.UK
DMR wonder cups are fab.
If you have a press in type BB, which is usual for single piece cranks, you can fit them and then use any standard mtb BB.
How that truvativ chainset you'll need a Raceface/Truvativ ISIS bb.

So many options :lol: :lol:


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PostPosted: Thu Dec 29, 2011 11:53 am 
Gold Trader / rb Rider / Special
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Joined: Mon Aug 31, 2009 12:26 am
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Location: Rurally close.
The hussefelts use their own specific bb i think? Mine do. Almost like isis but it has external cups. And there are 2 different chainline options to choose between.


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