What crankset will fit my frame?

PB Forum :: Dirt Jumping & Street
What crankset will fit my frame?
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flag tretal
Posted: Sep 7, 2015 at 5:18 Quote
I got a tweet tweet spank frame, and im looking for a crankset.
will this fit the frame?
http://www.chainreactioncycles.com/us/en/gravity-gravity-light-dh-megaexo-crank/rp-prod120575

and what would you reccomend?
flag ricar
Posted: Sep 12, 2015 at 19:42 Quote
Any crank with a euro 73mm BB.

Yes, that crank will fit.
flag tretal
Posted: Jan 21, 2016 at 1:12 Quote
tretal wrote:
I got a tweet tweet spank frame, and im looking for a crankset.
will this fit the frame?
http://www.chainreactioncycles.com/us/en/gravity-gravity-light-dh-megaexo-crank/rp-prod120575

and what would you reccomend?
I'm still looking for a crankset, my friend is selling his NSbike and i wounder if that would fit right on my frame.
He got one of those http://www.vitalmtb.com/product/guide/Bikes,3/NS-Bikes/Holly-2,2960

Thanks in advance.
flag ricar
Posted: Jan 21, 2016 at 10:17 Quote
I'm not sure what BB the Holy has not the Tweet. Regardless, the crank will fit but you may need a new BB. I believe they are both MID and if that is the case, then they will fit and you are done. I just wouldn't put money on that.
flag cmc4130
Posted: Jan 21, 2016 at 10:30 Quote
Note that if you use a bmx crankset, you'll likely need a 6 inch spindle instead of a 5.5" or 5.75" one (which are typical for bmx).

Bottom Bracket Help
https://www.pinkbike.com/forum/listcomments/?threadid=145972

The Spank Tweet Tweet appears to have a 73mm wide bb shell. The NS might have a 68mm wide bottom bracket shell . . . .


Profile Racing
Bottom Bracket Installation, Crank Installation, Bottom Bracket Information
http://www.profileracing.com/tech/bmx-cranks/
flag ricar
Posted: Jan 21, 2016 at 10:47 Quote
Throw another spacer on and ride it!!!
flag tretal
Posted: Jan 21, 2016 at 13:36 Quote
ricar wrote:
I'm not sure what BB the Holy has not the Tweet. Regardless, the crank will fit but you may need a new BB. I believe they are both MID and if that is the case, then they will fit and you are done. I just wouldn't put money on that.

I got Unsecure image, only https images allowed: http://www.alpebike.pl/images/7451_12389_50c21ff74e1ac.jpg its the dartmoor euro bb 22 mm. so its only possible to use 22mm axle with them I guess?

I will get the NS bike for only 80USD course the wheels was in so bad shape.. so I guess it would be worth it if I could use the crankset and get some spare parts too..
flag ricar
Posted: Jan 21, 2016 at 14:11 Quote
Yes, that BB will work with a crank with a 22mm spindle. Looks like it has spacers for a 68 and 73mm BB shell.
flag Metro-Gnome
Posted: Jan 21, 2016 at 19:06 Quote
I think Demolition cranks are available as 22mm, as are Twombolts. I have older Demolitions with a 19mm spindle, and they're stronger than anything else I've used. Can't imagine how strong the 22mm cranks are.

Having said that, I have a lot of experience with older DMR chieftian cranks (22mm as well). Super solid cranks, horrible, difficult to find, bottom brackets. I used to go months without a bb because back in those days I couldn't just buy a bb online with my phone and a credit card.

I am on my 8th 22mm bb (in my entire life between euro and spanish....and I'm pretty old)
Never had to replace a single bb besides that, and that's including Euro, Spanish, and every possible kind of mtb bb (Shimano, Race face, E13, Truvativ, Hope, Fsa, etc).

Edit_ I should add I have a decent understanding of 'Workshoppery' as I have worked in Bike shops, and as a machinist in my early 20s. I have 3 torque wrenches and a bike work stand and I even 'Improvised' a Truing stand to include a Dial Indicator. Google it, basically a depth measuring device that measures fractions of fractions. Unnecessarily accurate for truing, but I just use my fingers anyway.

What I'm saying is, I know how to install bbs, the tube spacer between them, and not crush the bearings. 22mm bearings are too small for my occasional cased landings
flag ricar
Posted: Jan 21, 2016 at 20:23 Quote
Yeah, 22mm spindles and Euro does not seem like a good idea. Even with 4 bearings. Maybe if they went with needle bearings.
flag tretal
Posted: Jan 21, 2016 at 22:38 Quote
ricar wrote:
Yeah, 22mm spindles and Euro does not seem like a good idea. Even with 4 bearings. Maybe if they went with needle bearings.

I dont really get it, what isn't a good idea?

Edit: is the tube between the "cups" suppose to be lose?
flag ricar
Posted: Jan 22, 2016 at 3:47 Quote
Nooooo, the tube must be firmly in place before you tighten your crank arms or you will crush your bearings. If the tube is too short use the longer one. If the longer one is too short you need to thread in the cups farther.

22mm spindles with a euro BB shell mean you need to run very thin bearings, not very strong bearings.
flag tretal
Posted: Jan 22, 2016 at 8:20 Quote
ricar wrote:
Nooooo, the tube must be firmly in place before you tighten your crank arms or you will crush your bearings. If the tube is too short use the longer one. If the longer one is too short you need to thread in the cups farther.

22mm spindles with a euro BB shell mean you need to run very thin bearings, not very strong bearings.
The longer tube is to long i guess(?), there is like 3 mm tills it touches the frame...
flag cmc4130
Posted: Jan 22, 2016 at 8:22 Quote
Yeah. Normally a 48mm tube spacer is used with a 68mm-wide bottom bracket shell, and a 53mm tube spacer is used with 73mm wide bb shell.

When I say "shell," I mean the part of the frame you would install the bottom bracket into. So,you would measure the 68mm or 73mm like this:
photo


You also may need to consider the spindle length. This old school Profile bmx spindle is not long enough (sorry I don't recall exactly how long it was) for a Black Market Mob with 73mm shell. As you can see, there's not enough room for the crank arm to sit on. A 6 inch spindle would be appropriate--not just so that the crank arms go on, but also for crank arm clearance with the frame.

Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/162_6213.jpg
Profile gives you various spindle length options:
Unsecure image, only https images allowed: http://www.profileracing.com/estore/images/product-images/343/crmospindles_5211_900.jpg
Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/Profile_6inch_spindle.jpg
Even if a 5.75" spindle works with your 73mm bb shell, you can still have a problem where the ends of the crank arms hit the frame. But, then you don't have enough spindle to space the cranks out further.

The back end of a BMX bike is spaced for a 110mm wide hub, but the back end of an MTB is spaced for 135mm. So, this is the reason why the chainstays often (not always) sit wider on a DJ mtb.

Pic of crank arm clearance with chainstays (not my bike, just random photo from internet).
Unsecure image, only https images allowed: http://fcdn.mtbr.com/attachments/transition-bikes/1009877d1440161726-chainstay-clearance-issues-scout-next-sl-cranks-img_2296.jpg
Crank Arm Clearance ?
http://ridemonkey.bikemag.com/threads/crank-arm-clearance.203808/
Unsecure image, only https images allowed: http://images.ridemonkey.com/index.php?size=full&src=http%3A%2F%2Fimg229.imageshack.us%2Fimg229%2F2164%2Fdcp2390mr9.jpg
So . . . back to the point. It may be that the NS has a bmx-style 5.75" spindle and 68mm bb shell. So you might have a crank arm clearance problem if you try to use the 5.75" spindle.
flag tretal
Posted: Feb 14, 2016 at 7:59 Quote
cmc4130 wrote:
Yeah. Normally a 48mm tube spacer is used with a 68mm-wide bottom bracket shell, and a 53mm tube spacer is used with 73mm wide bb shell.

When I say "shell," I mean the part of the frame you would install the bottom bracket into. So,you would measure the 68mm or 73mm like this:
photo


You also may need to consider the spindle length. This old school Profile bmx spindle is not long enough (sorry I don't recall exactly how long it was) for a Black Market Mob with 73mm shell. As you can see, there's not enough room for the crank arm to sit on. A 6 inch spindle would be appropriate--not just so that the crank arms go on, but also for crank arm clearance with the frame.

Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/162_6213.jpg
Profile gives you various spindle length options:
Unsecure image, only https images allowed: http://www.profileracing.com/estore/images/product-images/343/crmospindles_5211_900.jpg
Unsecure image, only https images allowed: http://i255.photobucket.com/albums/hh138/upsetbmx/Profile_6inch_spindle.jpg
Even if a 5.75" spindle works with your 73mm bb shell, you can still have a problem where the ends of the crank arms hit the frame. But, then you don't have enough spindle to space the cranks out further.

The back end of a BMX bike is spaced for a 110mm wide hub, but the back end of an MTB is spaced for 135mm. So, this is the reason why the chainstays often (not always) sit wider on a DJ mtb.

Pic of crank arm clearance with chainstays (not my bike, just random photo from internet).
Unsecure image, only https images allowed: http://fcdn.mtbr.com/attachments/transition-bikes/1009877d1440161726-chainstay-clearance-issues-scout-next-sl-cranks-img_2296.jpg
Crank Arm Clearance ?
http://ridemonkey.bikemag.com/threads/crank-arm-clearance.203808/
Unsecure image, only https images allowed: http://images.ridemonkey.com/index.php?size=full&src=http%3A%2F%2Fimg229.imageshack.us%2Fimg229%2F2164%2Fdcp2390mr9.jpg
So . . . back to the point. It may be that the NS has a bmx-style 5.75" spindle and 68mm bb shell. So you might have a crank arm clearance problem if you try to use the 5.75" spindle.

I bought this crankset http://www.chainreactioncycles.com/se/en/shimano-zee-m640-10-speed-chainset/rp-prod82416
i did install the BBs without spacers and the right arm hits the frame.
But if i use spacers the tube in the middle wont be "thru" the whole frame..
what to do? Razz
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