Bmx cranks on dirt jump

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Bmx cranks on dirt jump
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Posted: Apr 6, 2020 at 15:29 Quote
Hi guys,

I’ve currently got ns surge evo with isis cranks, do I need a new bottom bracket to fit these bmx cranks ?

My bottom bracket is bb73 please can you assist in what I will need.

Posted: Apr 6, 2020 at 15:32 Quote
what is the spindle size on the bmx cranks? some vary.

Posted: Apr 6, 2020 at 15:56 Quote
traqs wrote:
what is the spindle size on the bmx cranks? some vary.

I’ve ordered odyssey twombolt 2 piece cranks with 22mm spindle

Posted: Apr 6, 2020 at 16:44 Quote
good stuff. they are great cranks. hope they work out for you!

Posted: Apr 6, 2020 at 16:45 Quote
traqs wrote:
good stuff. they are great cranks. hope they work out for you!

So what bb will I need for my ns ?

Posted: Apr 6, 2020 at 19:33 Quote
https://www.pinkbike.com/forum/listcomments/?threadid=195676

https://www.pinkbike.com/forum/listcomments/?threadid=159138


Example of frame which takes a “Mid” bottom bracket.


Depending on the BMX cranks, you may need to have a longer spindle, like. 6 inch spindle with Profile cranks in order to get chainstay clearance.

Posted: Apr 7, 2020 at 14:17 Quote
cmc4130 wrote:
https://www.pinkbike.com/forum/listcomments/?threadid=195676

https://www.pinkbike.com/forum/listcomments/?threadid=159138


Example of frame which takes a “Mid” bottom bracket.


Depending on the BMX cranks, you may need to have a longer spindle, like. 6 inch spindle with Profile cranks in order to get chainstay clearance.

Thanks for yours help, I have 73mm bb I have purchase a set of odyssey twombolts and I have a feeling these won’t be appropriate due to the spindle length ????

Posted: Apr 7, 2020 at 21:00 Quote
harrisonlillis wrote:
cmc4130 wrote:
https://www.pinkbike.com/forum/listcomments/?threadid=195676

https://www.pinkbike.com/forum/listcomments/?threadid=159138


Example of frame which takes a “Mid” bottom bracket.


Depending on the BMX cranks, you may need to have a longer spindle, like. 6 inch spindle with Profile cranks in order to get chainstay clearance.

Thanks for yours help, I have 73mm bb I have purchase a set of odyssey twombolts and I have a feeling these won’t be appropriate due to the spindle length ????

Do you already have the frame? Measure the chainstay width like I did in the photo and see how wide it is. I don’t know exactly how wide the clearance is with Twombolts. They might be fine.

Posted: Apr 10, 2020 at 2:29 Quote
cmc4130 wrote:
harrisonlillis wrote:
cmc4130 wrote:
https://www.pinkbike.com/forum/listcomments/?threadid=195676

https://www.pinkbike.com/forum/listcomments/?threadid=159138


Example of frame which takes a “Mid” bottom bracket.


Depending on the BMX cranks, you may need to have a longer spindle, like. 6 inch spindle with Profile cranks in order to get chainstay clearance.

Thanks for yours help, I have 73mm bb I have purchase a set of odyssey twombolts and I have a feeling these won’t be appropriate due to the spindle length ????

Do you already have the frame? Measure the chainstay width like I did in the photo and see how wide it is. I don’t know exactly how wide the clearance is with Twombolts. They might be fine.

I emailed odyssey for the technical data on there spindle size. Here’s my response.

“A BMX frame BB width is 74mm (this is the actual measurement from edge to edge of the frames BB shell). Our Thunderbolt spindle is 85mm in the center order to accommodate spacers, if you exceed 85mm then the cranks wont compress correctly.

Our total spindle length is 117mm which includes the 24mm integrated sprocket seat.

Long story short, if we are only off by 1mm then it should be okay.”

Hopefully a 22mm euro bb with the right spaced should do the trick!

Posted: Apr 10, 2020 at 9:14 Quote
harrisonlillis wrote:

I emailed odyssey for the technical data on there spindle size. Here’s my response.

“A BMX frame BB width is 74mm (this is the actual measurement from edge to edge of the frames BB shell). Our Thunderbolt spindle is 85mm in the center order to accommodate spacers, if you exceed 85mm then the cranks wont compress correctly.

Our total spindle length is 117mm which includes the 24mm integrated sprocket seat.

Long story short, if we are only off by 1mm then it should be okay.”

Hopefully a 22mm euro bb with the right spaced should do the trick!



That's an odd answer in a couple different ways. First, I had never heard of 74. I have heard of 68mm and 73mm bb shell widths. Note for example this S&M BMX web page that says "Mid Bottom Bracket
We use a standard 73mm Mid BB shell on all custom frames that call for them." and "Euro Bottom Bracket
We use a standard 68mm Euro BB shell on all custom frames that call for them."

https://www.sandmbikes.com/custom-frame-options/

Secondly, a 117mm spindle length is very short. It's only 4.6 inches. Maybe they mean "excluding" the 24mm integrated sprocket seat, not "including" it??

I'm looking at the specs here:
https://shop.odysseybmx.com/products/thunderbolt-plus-cranks

The main question is how wide is the inside distance between the left and right pedal boss areas and how much chainstay clearance that gives.

What frame are you going to put these on? The NS Surge Evo? Well, I put BMX Profiles with a 6 inch spindle on my NS Surge Evo. https://www.profileracing.com/product/gdh-chromo-crank-axle-19mm/


Posted: Apr 10, 2020 at 12:06 Quote
cmc4130 wrote:
harrisonlillis wrote:

I emailed odyssey for the technical data on there spindle size. Here’s my response.

“A BMX frame BB width is 74mm (this is the actual measurement from edge to edge of the frames BB shell). Our Thunderbolt spindle is 85mm in the center order to accommodate spacers, if you exceed 85mm then the cranks wont compress correctly.

Our total spindle length is 117mm which includes the 24mm integrated sprocket seat.

Long story short, if we are only off by 1mm then it should be okay.”

Hopefully a 22mm euro bb with the right spaced should do the trick!



That's an odd answer in a couple different ways. First, I had never heard of 74. I have heard of 68mm and 73mm bb shell widths. Note for example this S&M BMX web page that says "Mid Bottom Bracket
We use a standard 73mm Mid BB shell on all custom frames that call for them." and "Euro Bottom Bracket
We use a standard 68mm Euro BB shell on all custom frames that call for them."

https://www.sandmbikes.com/custom-frame-options/

Secondly, a 117mm spindle length is very short. It's only 4.6 inches. Maybe they mean "excluding" the 24mm integrated sprocket seat, not "including" it??

I'm looking at the specs here:
https://shop.odysseybmx.com/products/thunderbolt-plus-cranks

The main question is how wide is the inside distance between the left and right pedal boss areas and how much chainstay clearance that gives.

What frame are you going to put these on? The NS Surge Evo? Well, I put BMX Profiles with a 6 inch spindle on my NS Surge Evo. https://www.profileracing.com/product/gdh-chromo-crank-axle-19mm/


Thanks for your help is your surge evo 73bb ?

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