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The Street => The Bike Shop => Topic started by: Davet on August 06, 2018, 04:07:42 PM

Title: MID BB width
Post by: Davet on August 06, 2018, 04:07:42 PM
Has the standard width for MID BB changed since it came out?, I have a S&M dirt bike from about 7 years ago with the mid BB and I just got some new Madera cranks, the spindle is 6" and too long, the profile site says "5.625″ (For BMX Freestyle Bikes)" I was gong to get a new frame in a couple months anyway but just wondering, thanks!

It looks like it would have been a change from 68mm to 73mm, it's not something I've ever thought about, I just thought there was one width for mid bbs
Title: Re: MID BB width
Post by: JohnW on August 06, 2018, 10:03:50 PM
I've seen varying widths over the years, I think they went wider for more tire clearance now that 2.45 tires exist. If it's too long you can always add more spacers, as long as that doesn't push the pedals out too far.

G why did all the Q-factors get so wide???
Title: Re: MID BB width
Post by: weedbix on August 07, 2018, 09:47:50 PM
I've seen BB's as wide as 8cm

MAkes chain alignment a pain unless you have a hub where the driver teeth sit closer to the dropout like a Ratchet (antigram too maybe? never measured)
Title: Re: MID BB width
Post by: Davet on August 08, 2018, 07:02:32 PM
Jeeze, now I have to worry about the rear hub width too? haha, I thought BMX had standardized most measurements a while back

Appreciate the info, I should be able to get something working now
Title: Re: MID BB width
Post by: andreas on August 09, 2018, 07:55:58 PM
There are lots of new things fucking up the rear end that keep us from reaching that point where we have perfect chainlines on every bike. Fat tires, brakeless(?), shorter chainstays, hubguards are all pretty standard now and it seems that these things haven't been perfectly incorporated into every setup yet without little things going unnoticed.
Title: Re: MID BB width
Post by: JFax on August 13, 2018, 03:03:16 AM
Fairly sure the BB width has never been standarized. I have at least never had the possibility to just pop in a tub spacer and have it fit nicely. Always had to trim or add shims, such a pain...