BMX BB Adaptor?

Workshop tales, trials and disasters.
Maintenance tips, techniques and myths.
Technical discussion, description and outright lies

BMX BB Adaptor?

Postby kukamunga » Thu Feb 14, 2008 12:28 pm

I'd like to fit a 'conventional' road/MTB Bottom Bracket to a BMX BB shell. Can anyone make some recommendations? I am not very familiar with the innards of a BMX BB shell. I picked up a Specialized 'Fatboy' BMX with a snapped-off LH pedal thread. I would like to retrofit with one of a few BB/ cranksets I have, or maybe even a new external bearing crankset. Cheers :)
Posts: 3525
Joined: Sat Dec 08, 2007 9:12 am
Location: 3166

by BNA » Fri Feb 15, 2008 9:02 am


Postby kukamunga » Fri Feb 15, 2008 9:02 am

Geez. It's quiet here without Richard around... (wind whistles... tumbleweeds roll by....) :roll:
Posts: 3525
Joined: Sat Dec 08, 2007 9:12 am
Location: 3166

Postby Kid_Carbine » Fri Feb 15, 2008 9:08 am

Let me understand.
You have a BMX bike with the large diameter Ashtabula bottom bracket & one piece crank, ... & you want to find an adapter that allows you to fit a regular type of B/B.
I know that such a thing was made, so perhaps a visit to a large & long standing bike shop would produce results.
I say 'long standing' as they will hopefully have someone there who has been around long enough to remember, & may even still have one in stock.

Any particular reason for the switch? After all, the Ashtabula cranksets have been around for a while & are a proven thing in BMX.
Carbine & SJH cycles, & Quicksilver BMX
Now that's AUSTRALIAN to the core.
User avatar
Posts: 1297
Joined: Tue Aug 14, 2007 11:35 pm
Location: Southern Highlands N.S.W.

Re: BMX BB Adaptor?

Postby HappyHumber » Fri Feb 15, 2008 9:27 am

kukamunga wrote:I'd like to fit a 'conventional' road/MTB Bottom Bracket to a BMX BB shell.

No personal experience with such a mod - but your request did remind me of something I had seen before;

Depending on how determined you are you could always order one from the US if leads closer to home draw blanks. There's a few related bits of info here and also the adaptor you want, part way down the page: Look up the Truvativ site or see if your LBS has a distrubutor catalogue which may list it also

Just skimming through that text - the one piece cranks (or 'Ashtabulas' as they seem to be referred to in some contexts) generally have a different sized pedal threading - thereby limiting your choice of regular pedals ?
- Kym
Since I keep misplacing my common sense down the shed, I guess I'll have to borrow someone elses off the internet.
User avatar
Posts: 4844
Joined: Wed Nov 14, 2007 10:48 pm
Location: Perth, (S.o.R.) W.A.

Postby kukamunga » Fri Feb 15, 2008 9:43 am

Just done some searching. This is the sort of thing I am after:-
TruVativ BB Adapter, NZ$30.00. Of course, Dirtworks do a 'DMR' brand one at twice the price! :? I might check out my local BMX shop/s. I'd like to not have to muck around with another type of BB and crankset (and tools), and try and keep my ever increasing bike stable a bit standardised (becoming increa$ingly difficult). There are some pretty solid external bearing, single ring cranksets and BB combos out there at good prices now.

This is similar to what I picked up:-
Just the thing for my 4 1/2 year old for when he gets bigger (and me in the meantime? Uh oh...) :shock: :roll: :) 8)
Posts: 3525
Joined: Sat Dec 08, 2007 9:12 am
Location: 3166

Return to The Shed

Who is online

Users browsing this forum: No registered users

Popular Bike Shops
Wiggle Wiggle UK
Torpedo 7 Cycling Express
Ebay Ebay AU
Chain Reaction Cycles CRC UK

“Bicycles BNA Twitter
“Bicycles BNA Facebook
“Google+ BNA Google+
“Bicycles BNA Newsletter
“Bicycles BNA on Strava