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Author Topic: aluminum bb spacer idea thingy  (Read 947 times)

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Offline blueee

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aluminum bb spacer idea thingy
« on: November 18, 2017, 12:04:15 PM »
so I finally caved in and got a frame with a mid bb, one mid bearing weighs as much as like 2spanish bearings. all this extra weight is very upsetting

could it be possible to fabricate a lil aluminum spacer thingy to put between a mid bb she'll and a Spanish bearing? just a thought

Offline Professor Horatio Hufnagel

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Re: aluminum bb spacer idea thingy
« Reply #1 on: November 18, 2017, 03:33:03 PM »
Mid bearing outer diameter: 41.275mm
Spanish outer diam: 37mm

A lot closer in weight than you suggest. Add in a 2.1375mm cup (with lip to locate the bearing) and the weight loss (for the MIDDLE of your bike where rotational weight is 1:1 not 2:1 or 1.5:1) and you're really not acheiving anything but overly complicating things for yourself, paying money and/or spending time on a machine
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Offline blueee

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Re: aluminum bb spacer idea thingy
« Reply #2 on: November 19, 2017, 08:56:17 AM »
I wouldn't it simply be like an oddshaped washer with a lip on it? what if I were to use a Euro bb bearing so the thingy had more substance and less steel in the bearing? o?

Offline Gary

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Re: aluminum bb spacer idea thingy
« Reply #3 on: November 19, 2017, 03:43:12 PM »
Bluee are you thinking along the lines of a non concentric BB adaptor or just to fit the smaller bearings? If its just to fit the bearings  Professor Horatio Hufnagel has it cold. Think of the heavy ass old American BB adapters, not worth it.



Offline metalbmxer

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Re: aluminum bb spacer idea thingy
« Reply #4 on: November 20, 2017, 07:54:08 AM »
You can save weight by not running the tube spacer. Seriously

Havenít been running one for years and the mid bearings are beefy enough to handle it

Offline blueee

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Re: aluminum bb spacer idea thingy
« Reply #5 on: November 20, 2017, 09:16:16 AM »
I should definitely drill holes in my tube spacer

Offline Professor Horatio Hufnagel

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Re: aluminum bb spacer idea thingy
« Reply #6 on: November 21, 2017, 06:36:19 AM »
Apart from being terrible for your BB bearings (which are radial, not thrust or ACB, i.e. engineered for axial loads), not running a tube spacer will lead to your sprocket bolt coming undone, and your spindle bolts too if you don't have pinchbolt cranks. One of the subtle things that 99/100 people don't realise, like how most hub wobble in hubs with a 14mm or 3/8" axle is caused by non-parallel dropouts or exploded driver bearings being caused by the bearing shoulder on the axle not being a right angle but instead a curve
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Offline George

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Re: aluminum bb spacer idea thingy
« Reply #7 on: November 21, 2017, 02:41:57 PM »
i did that once some time ago. you need to make a custom tube spacer too probably. All in all saved 40 grams over Mid ircc and was a cool exercise on tolerances.
you could even buy them from khe back in the days

Offline blueee

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Re: aluminum bb spacer idea thingy
« Reply #8 on: November 22, 2017, 09:40:50 PM »
wow, over an oz in savings, almost two! any chance I can buy the cups off you?

Offline Professor Horatio Hufnagel

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Re: aluminum bb spacer idea thingy
« Reply #9 on: November 23, 2017, 12:55:38 AM »
1.4 by my count
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Offline Sasha

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Re: aluminum bb spacer idea thingy
« Reply #10 on: November 26, 2017, 12:10:11 PM »
Just cut your crankarms off.

Offline Professor Horatio Hufnagel

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Re: aluminum bb spacer idea thingy
« Reply #11 on: November 26, 2017, 10:23:37 PM »
That joke falls flat, I presume you had to do it over a hip to get it there
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Offline JFax

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Re: aluminum bb spacer idea thingy
« Reply #12 on: November 27, 2017, 08:37:33 AM »
Could always try and get some sealant or glue and try and center your bearing in the frame. If you use silicone it might also work as a suspension for your cranks, haha.
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Offline Professor Horatio Hufnagel

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Re: aluminum bb spacer idea thingy
« Reply #13 on: November 27, 2017, 03:23:53 PM »
He'd probably take that seriously in the quest to make his 11,340g bike weigh 11,300g
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Offline Cellmember

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Re: aluminum bb spacer idea thingy
« Reply #14 on: December 13, 2017, 05:57:11 AM »
Vitalbmx: Cellmember
Bmxforum: Cellmember
Bmxmuseum: Cellmember
Ref\'s: http://www.bmx-forum.com/u/64216/cellmember

Bikeguide.org - Bike maintenance for BMX'ers

Re: aluminum bb spacer idea thingy
« Reply #14 on: December 13, 2017, 05:57:11 AM »

 


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