Bent 3pc Bottom Bracket

markz

100 TW
Joined
Jan 9, 2014
Messages
12,179
Location
Canada and the USA
Threaded BB
3 Piece bottom bracket
Square taper
90mm Shell
Nut style retainer for crank arms, not bolt
16.26mm diameter axle (in the middle)

Bent my bb on a fall on the crank side. At first I thought just the crank bent, but I replaced crank to confirm it has a 3-4mm wobble from small gear to edge of bb shell and the 'bent-in' side is on the pedal side. Pics taken and its noticeable.

When taking the BB apart, I took the axle to a straight edge and its obviously bent. Pics taken and its noticeable.

Weight wise, 52V 14.5Ah Grin battery on top of top tube, another battery in the triangle 36V 20Ah, controller on top tube.
I am 325lbs. Fell onto crank side, bent basic outer metal pedal edge inward, got me a big ole scab, even bigger bruise and road rash on the top part and its taken 1 month to get to red.

I took lots of pictures.

Its got the threaded cups on either end, took an adj wrench to take off the drive side, and the cup came out with greased bearing ring inside then I took the axle itself out with the bearing ring on the axle, I left the other side cup on. Looks good that there's lots of grease in there. I was concerned when undoing the threaded cup because lots of sandy bits came out. Looked inside the BB and it wasnt to bad. Did the usual WD40 and paper towel to clean it all up.

One option I thought of is to buy a mid drive bb from Cyclone Taiwan which comes in square tapered 68-120 and use it on my front hub ebike. Luna has both styles of bb axle in 68-100. But if I go that route, might as well install my Cyclone 4kw.

I see 80mm shell width come in cartridge, some proprietary Trek's come close to 90mm, can't find no cartridge for 90mm shell. All I can find for 3 pc's are 68 shell widths.

What do you figure, where to buy a 3pc bb with 90mm shell and 175mm? 195mm? axle (do you count the threads or just end of tapers.
 

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Most square taper spindles are hard enough that they won't bend like yours did. They snap off. (Ask me how I got my fancy gold teeth.)

You're now on the receiving end of a nonstandard BB standard. This is why we can't have nice things.

https://www.ebay.com/itm/274694554463
 
Do you see any problems with the "?stock bb?" being 90x175mm and that ebay one being 90x142?
I bought the bike used, might not be an original bb or original 1x crank, I also learned the previous owner had installed a 160 rear hub (bolt on) on a 180 rear dropout that he shoved a bolt underneath the axle to space the disc from caliper because the adapter didnt have concave spacers and when I reinstalled wheel after flat the disc hit rotor not knowing the bolt fell out. I had a 170 rear hub wheel I installed with QR. So I guess the whole chainline question is irrelevant until I get a proper 180 rear hub wheel. Both sides bend inward when tighting the rear wheel, I just make sure disc side is flush then squeeze in gear side, not sure which way I did it in the pic as the bike is now no rear disc installed.

142 vs 175 would bring the crank gear inward I'd assume 16.5mm (87.5-71) compared to the rear 7 gear freewheel.
It looks like the big chain ring does need to come in to be in the middle of the rear freewheel.

I tried to get a good pic of the chainline. Yea its a 3x spare I have, the 1x icame with the bike. Who knows if the stock crank was original.

I hammered the axle back a bit but I wont pedal until its replaced. :mrgreen:



Best pic I got, doesnt show much does it.
But eyeballing the chain is inline with that chain stay. Looks to me the chain ring can come in a bit.
I will install original crank tonight and get better pics.


Screenshot 2021-07-29 135725.png


Chalo said:
https://www.ebay.com/itm/274694554463
 
That chainline looks horrible. If you don't need the longer spindle to keep the chain from rubbing the tire, use a shorter one.

Heavy as you are, you should be on BMX cranks to prevent hurting yourself. I recommend Profile Racing cranks because they offer lots of crank lengths and several different spindle lengths. But they're not cheap.
 
I agree, that chain line is one of the worst I have ever seen. That can't be the correct BB for that frame. It looks ~30mm too long on both sides.

Chalo said:
That chainline looks horrible. If you don't need the longer spindle to keep the chain from rubbing the tire, use a shorter one.

Heavy as you are, you should be on BMX cranks to prevent hurting yourself. I recommend Profile Racing cranks because they offer lots of crank lengths and several different spindle lengths. But they're not cheap.
 
Thanks Raylo and Chalo.

I found 2 dealers of my bicycle brand, hopefully they will have the parts I need, BB, rear hub or wheel.
https://www.surface604bikes.ca/pages/dealer-locator

Progress report: I hammered the axle back a tad, and went up a real steep hill today to see how easily the chain would slip off on my spare ccm 3x crank and it stayed on. I was in the middle crank gear with the small rear gear, straight enough chain line. I won't be doing many more of that until the fix, back to my normal route with easy wot hills.

Stock crank is a Prowheel Solid 1x, I counted 46T not 48T but hey I could be wrong.
https://electricbikereview.com/surface-604/element-electric/
Cranks: ProWheel SOLID 248T-F Aluminum Alloy-6061 48T, 170 mm

Seems the Jak Superbrake is also stock, I thought it wasnt. Thats been replaced with Avid BB7.
Brake Details: JAK SuperBrake Mechanical Disc with 177.8 mm (7") Rotor, KARASAWA Levers

The 1x crank gear could come inward 10-15mm. I dont know if I really want a 1x crank, a e-type bb mounted front derailleur with a 3x crank in a 48/38/28 and a 13-34 would do me nice cruising while pedaling and hills.

Thanks Chalo, yeah you mentioned BMX cranks a couple times before, but I am to cheap for my own good :lol:
But I just might splurge, just maybe, but I dont know about sticking with a 1x. Sure no front shifter, no chain falling off the crank, no e-type fd. I am pedaling more, doing more hills just to break a sweat and work out but I also put on the mileage cruising at fast casual speeds and like to help out pedaling.

So a BMX crank set will fit a 90mm bb shell?
https://www.profileracing.com/product-category/profile-bmx/profile-cranks/
6.875″(for 83mm & 100mm Euro BB’s)
6.0″(for 68mm & 73mm external Euro BB’s)


OK here is the stock 1x Prowheel crank, tightened on the square taper.
Please note these pics are with a totally loosened skewer and hub shifted all the over to the gear side.

You can see how the chain bends at the stock 1x crank, I think the crank itself is bent as well as the bb axle. I was riding around today with the 3x crank and the chain doesnt bend as much at the crank. Now the stock 1x crank has been off so the bent axle could very well be in a different position compared to bent crank, I mean I have a 25% of getting it right.
 

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markz said:
So a BMX crank set will fit a 90mm bb shell?
https://www.profileracing.com/product-category/profile-bmx/profile-cranks/
6.875″(for 83mm & 100mm Euro BB’s)
6.0″(for 68mm & 73mm external Euro BB’s)

Profile and other 48 spline BMX cranks are extremely chainline adjustable. You have to space the bearings apart according to the width of the BB shell. In your case, that probably means adding 7mm of thin washers to the spacer tube for an 83mm BB.
 
BMX bikes and parts are something I have never worked on. But I just looked at the Profile website and they don't seem very $$... at least compared to my normal higher end road bike gear... so Mark you must really be cheap! ;) Although I don't understand what all the miscellaneous parts are for and what you might need to make it work.

And those balls-in-cage BB bearings... I haven't used those since the early 1990s when I had a MTB BB bearing fail me in a snow shower up in the mountains. Get something with sealed bearings.


Chalo said:
markz said:
So a BMX crank set will fit a 90mm bb shell?
https://www.profileracing.com/product-category/profile-bmx/profile-cranks/
6.875″(for 83mm & 100mm Euro BB’s)
6.0″(for 68mm & 73mm external Euro BB’s)

Profile and other 48 spline BMX cranks are extremely chainline adjustable. You have to space the bearings apart according to the width of the BB shell. In your case, that probably means adding 7mm of thin washers to the spacer tube for an 83mm BB.
 
This company has some interesting bottom brackets. I purchased the 153mm bottom bracket to create clearance between my crank arms and battery case. But yeah they have some unique bottom brackets that might help in your situation.

https://sickbikeparts.com/bicycle-parts-and-tools/
 
Those guys have some interesting parts for sure. Thanks for sharing the link.

Eastwood said:
This company has some interesting bottom brackets. I purchased the 153mm bottom bracket to create clearance between my crank arms and battery case. But yeah they have some unique bottom brackets that might help in your situation.

https://sickbikeparts.com/bicycle-parts-and-tools/
 
Eastwood, thanks a bunch for that link, SBP slipped my mind, their price of $27 is good, shipping prices to Canada are reasonable at $23 and hopefully no surprise bill months later like what FedEx pulls with Luna Cycle for ground shipping into Canada.

Raylo - I have looked into the BMX and its a little confusing since I never dealt in BMX before but I do remember Chalo telling me about it and my wallet shivered. :lol:
BMX specs never/hardly ever specify bb shell widths which is what threw me off but thanks to Chalo's knowledge I looked into it again. If I want to keep this bike instead of sell it then I'd go for good quality, expensive components. Orange is a little to eye catching and there isnt enough triangle space for a decent size battery.


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Saved draft

There are two authorized dealers for my bike here, I will go to both and ask them about a new bottom bracket. Though the one store looks to be a warehouse but its quite a long ride. Phew luckily I checked their website, says appointment only, I sent them an email since they are a licensed dealer I just hope they can sell me the rare, specialized 90mm bottom bracket that no one has.
The other place is downtown and I've been there before because they do custom cut spokes.

BMX crank option - Luckily there is a local bike shop that specializes in BMX, I will ride up there and see what they got.
I will come prepared with a dusted off credit card, will be a pricey matter, could almost buy a hub and slap it on a bike profit then blow cash on the bmx crankset. :lol:

There is Outboard and Inboard Euro, I will probably go inboard 19mm.
https://www.profileracing.com/tech-tip-3-what-is-going-overboard/
https://bmxmuseum.com/forums/viewtopic.php?id=279037
the outboard bearings will stick out about 4-6mm outside the shell. If your spindle is long enough and you don't mind the wider stance, it shouldn't matter. I've only seen them on Mtn bikes, and your spindle may not need to be wider, but it may need to be, I don't know.
When I contacted Profile on this, they recommended using one of their spiders that has an offset to move the chain-ring back to where it should be. But I didn't want a spider.

Outboard - https://www.profileracing.com/product/euro-externaloutboard-bottom-bracket/
Inboard - https://www.profileracing.com/product/euro-internal-bottom-bracket/

Then I gotta go 48 spline axle spindle in 19mm 6.875"
19mm tube spacers - https://www.profileracing.com/product/22mm-tube-spacers/
More spacers (22mm = 3/16, 3/64, 0.025) - https://www.profileracing.com/product/crank-bb-washer-spacer/
Crank Arms need to be 48 spline and match 19mm, lots of lengths to choose from- https://www.profileracing.com/product/ss-crankarm-set/

Like I said, I don't know about going the BMX crank route with only 1 crank gear, E-type front derailleur and a 2x or 3x crank will suit my needs perfectly, pedaling with 52x13 for cruising the pathways at a steady constant speed and saving juice extending my range by 15km, and the steep hills to climb in something like a 28or32x36 which only really need for 50' as most hills I wot before the hill to get up half the hill, the first 20-35% is in gears like 44x13, the middle part of hill in a mid gear like a 34x20 then the last bit of steep hill is always pumping hard and breaking a sweat at 22x36.
 
markz said:
Like I said, I don't know about going the BMX crank route with only 1 crank gear, E-type front derailleur and a 2x or 3x crank will suit my needs perfectly,

Fear not. Other folks thought of that over 40 years ago.

https://www.jbi.bike/site/product_details.php?part_number=21395

https://www.profileracing.com/product/spider-bolt-on-double-triple/
 
Your a wealth of knowledge Chalo

TYVM

:thumb:

Chalo said:
markz said:
Like I said, I don't know about going the BMX crank route with only 1 crank gear, E-type front derailleur and a 2x or 3x crank will suit my needs perfectly,

Fear not. Other folks thought of that over 40 years ago.

https://www.jbi.bike/site/product_details.php?part_number=21395

https://www.profileracing.com/product/spider-bolt-on-double-triple/








--------------------------------
Edit

Here is an update from the authorized dealers that I emailed.
Basically "You are shit out of luck"
aka
"Those are not available, cant get them, bike is too old, that BB was odd shape.
I am not even sure if any aftermarket will fit."
but you could try."

So I dont know what the odd shape comment was about, probably just meant odd length bb shell.
So that makes me wonder how long did they weld these useless bottom bracket shells onto their bicycles
and what are they using now.
They must've wanted a certain chainline to choose such an odd bottom bracket. What was going through the manufacturers engineers mind when they came up with a impossible to get 90mm bottom bracket.
 
You should really keep your eyes peeled for an affordable used downhill bike, then add spring rate as needed. Something designed to be launched off of the side of a mountain is going to hold up better for someone of your stature, even if you're just using it to tool around town. You've posted of numerous hard part failures over the years and it would suck for you to sustain serious injury because the thing decided to fold underneath you. I can appreciate that money doesn't grow on trees, but sometimes it's worth it to invest in quality.
 
Yeah I could and perhaps I should of bought a downhill bike
but I like my triangle space for battery
Full suspension would indeed need to be dialed in, maybe once I get under 300lbs theres stock setups that may hold my weight with aftermarket heavier springs, rebuilding air shocks perhaps, yes, anything is possible throwing enough money at it. I know on the MTBR forums theres some in the Clydesdale section that are 275lbs that ride full suspension. The best I could hope for is a nice suspension fork, fat cushy tires and maybe a suspension seat post.

As it stands right now, I've been riding the bent bottom bracket axle for 2 weeks now. Bent the axle back best I could a week ago, fine for casual pedaling but once on hills it slips off down from 44T, or up and jams into the guard. I will keep trying to bend it back, might try some heat.

Been thinking about the situation for 2 weeks now
What if I get a shop to cut BB down and rethread?
That'll probably cost a lot, so Chalo's bmx crank would be cheaper.

Another route I was contemplating was figuring out how to get extra length on the bb shell to get 100mm, 5mm each side of 90mm. Welding would be out of the question due to accuracy needed and warping. But I saw some normal adpaters you slide in with bolts, is a common adapter and shell width was the same but it got me thinking.
Problem is the adding of more shell width. I regret buying that bike now, but I shouldn't have fallen.

I will bite the bullet and buy that ebay bb.

HK12K said:
You should really keep your eyes peeled for an affordable used downhill bike, then add spring rate as needed. Something designed to be launched off of the side of a mountain is going to hold up better for someone of your stature, even if you're just using it to tool around town. You've posted of numerous hard part failures over the years and it would suck for you to sustain serious injury because the thing decided to fold underneath you. I can appreciate that money doesn't grow on trees, but sometimes it's worth it to invest in quality.

Chalo said:
Most square taper spindles are hard enough that they won't bend like yours did. They snap off. (Ask me how I got my fancy gold teeth.)

You're now on the receiving end of a nonstandard BB standard. This is why we can't have nice things.

https://www.ebay.com/itm/274694554463
 
If you found something with long travel and stuffed a 500-750lb spring into it your weight would be a non issue for general purpose riding. Consider the forces involved when a 175lb person flies down a mountain at 60mph, goes off of a jump and lands it. Many magnitudes more force would be exerted than yourself under normal riding conditions.

As for triangle space, it's just a matter of finding an old downhill bike circa early 2000's. As a benefit they will be cheaper than anything made recently. Or you could finally grab a bomber style frame for a few hundred. Even the cheap knockoffs would handle your weight for general purpose riding assuming you threw enough spring under it. Even a cheap DNM rear coil shock would do.
 
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