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-   -   Does this flange look cracked to you? (https://www.bikeforums.net/bicycle-mechanics/1226977-does-flange-look-cracked-you.html)

rickpaulos 03-28-21 04:14 PM

Does this flange look cracked to you?
 
Gary Fisher Mt Tam with a Bontrager rear hub.
the bike is ~20 years old, ridden on gravel trail tours by a middle age woman. No aggressive riding.
I'm doing a complete overhaul on it.

the cassette was coming unscrewed from the hub shell. so the rear wheel got a good cleaning (20 years worth of road crud).
radial spoke pattern on the left side. We know that can rip flanges apart. Or is this visual damage from something caught up around the hub? There is some but very little wear on the spokes at the hub. I tried squeezing hard on the spokes but I didn't see any cracks open up. It looks like slight cracks midway between the spoke holes. I'd expect cracks to form at the spoke holes if this is a radial spoke pattern failure.

This hub has oversized cones with 3/16 balls, 12 on each side. No visible wear on the cones. Pretty high quality stuff. not sure if it's ever been apart before.

if you click on the photos, it should zoom in.

Toast or not?

https://live.staticflickr.com/65535/...543a1f92_b.jpg

https://live.staticflickr.com/65535/...dc2dc4c6_b.jpg

https://live.staticflickr.com/65535/...1ecc482d_b.jpg

https://live.staticflickr.com/65535/...76e049ff_b.jpg

https://live.staticflickr.com/65535/...e63cf791_b.jpg

https://live.staticflickr.com/65535/...06d6debe_b.jpg

Iride01 03-28-21 04:21 PM

You'd have to put it in paint or something and add an arrow to where you think it's cracked. All I see is someone rode it with the chain caught between the cog and spokes. Impressed that it could be ridden at all that way.

base2 03-28-21 04:30 PM

Radial lacing is usually done with the spoke emerging from the inboard side of the flange. Yours is backwards.

It looks like the spokes have levered the flange over. I wouldn't trust it & I'd further have a talk with whoever built that wheel.

To my eyes, it has the characteristic stressed aluminum look that would always make us aluminum airplane mechanics leery of what the dye penetrant would find.

rickpaulos 03-28-21 04:38 PM

This is the left side of the wheel, not the drive side so it's not chain damage. Original factory wheel on the bike. "Made in the USA" rims and bike.

Troul 03-28-21 04:44 PM

what made the coating come off & interfered with the spokes?

rickpaulos 03-28-21 08:24 PM

No idea on what caused the scraping. The bike is 20 years old or more and I just got it a few weeks ago. No stories of damage from the previous original owner other than the shifters. The left stopped clicking and her bike shop of choice put a Tourney on to replace the XT and she was pretty disappointed. She had ridden it on trails all over the USA and moved on to a "gravel bikepacking bike.

anyhow, I reversed the radial spokes so they are heads out. finished up the overhaul and reassembly. Back on the road tomorrow as my commuter this spring.

Geepig 03-29-21 02:57 AM

While it was in pieces I would have done something to try and polish out those ridges, because no one needs to discover the worst far, far from base ;)

Ghazmh 03-29-21 06:15 AM

Yes, I see what I believe is cracks in addition to elongated holes and corrosion. I would consider that hub as non serviceable and replace before riding that bike.

easyupbug 03-29-21 07:07 AM

At a bare minimum I would spend $10 on a spray can of dye penetrant to see if you have surface cracking, an aluminum crack can progress very quickly and it that location be very serious.

Iride01 03-29-21 10:29 AM


Originally Posted by rickpaulos (Post 21989218)
This is the left side of the wheel, not the drive side so it's not chain damage. Original factory wheel on the bike. "Made in the USA" rims and bike.

I actually was sort of thinking that when I replied. Figured I'd let you set me straight instead of writing more confusing ifs, ands or buts.

I can still imagine that just being something got caught in the stays or wrapped around the wheel and wasn't dealt with immediately.

For that to turn out to be stretching of the flange is going to really be something that will impress me.

rickpaulos 03-29-21 10:52 AM

I now think both causes. Something caught up that scraped in all up and improper spoking. the front wheel is spoked radial with the heads in but the flange is much smaller so it think it would resist that leveraging stress and being a front wheel, it doesn't have the same cyclical pedaling forces.

I don't there is much danger. If/when it fails, the wheel will get loose and wobbly, not much different from a flat tire.

I wonder if Trek has a engineer/designer in charge of wheels. Would their warranty cover it 20 years later for a different owner. sure not.

I have seen broken flanges but not often. Most are from radial spoking just pulling harder than the flange can take or the old sturmey archer aluminum 3 speed shells that were way to thin. With most of the newer boutique wheels, the rims fail far more often because the fewer spokes are under much more tension and the stress is focused on points on the rim farther apart.

Sluggo 03-29-21 04:05 PM


Originally Posted by easyupbug (Post 21989890)
At a bare minimum I would spend $10 on a spray can of dye penetrant to see if you have surface cracking.. [snip].

This is a good idea and one that could have applications for other parts that cause worries. However, I can't find anything on a quick search for only $10. Everything I could find required several steps and an equal number of products. The small Magnaflux kit is $150 or so. It still might be worth it, expecially if you want to use older components with confidence. Do you have a specific $10 product in mind?

oldbobcat 03-29-21 06:41 PM

At bare minimum I'd re-lace that side of the wheel 3-cross. If it was my own.

easyupbug 03-29-21 07:02 PM

Prices have really gone up, with penetrant and developer which you have to have your in it for $30. You do not need a cleaner for your hub just be sure it is spotless with a hydrocarbon cleaner. In the old days we clean the parts and applied kerosene allowing it some time to soak into a crack and surface dry and then paint with whitewash (mix of hydrated lime, a little salt and water, the kind at Home Depot that masons use, not garden line the dolomite stuff), If there were any cracks, the kerosene in the cracks wicks up discoloring the white wash.

79pmooney 03-29-21 07:16 PM


Originally Posted by rickpaulos (Post 21989519)
No idea on what caused the scraping. The bike is 20 years old or more and I just got it a few weeks ago. No stories of damage from the previous original owner other than the shifters. The left stopped clicking and her bike shop of choice put a Tourney on to replace the XT and she was pretty disappointed. She had ridden it on trails all over the USA and moved on to a "gravel bikepacking bike.

anyhow, I reversed the radial spokes so they are heads out. finished up the overhaul and reassembly. Back on the road tomorrow as my commuter this spring.

So do I have this right? You rebuilt this wheel but haven't addressed finding out if that is a crack? Yes, that will probably change the life of this hub before that crack goes through but it is anybody's guess whether that failure will come sooner or later. (Changing spoke direction on a re-build is generally considered a no-no. Reversing direction is not the same, but still ...)

rickpaulos 03-30-21 12:51 PM

Different lighting, different camera. I scratched a small X over what I thought was a crack. Now it looks like those cracks are remains of paint left by what ever was caught up in the wheel.

The rim is an off set rim with all the spoke hole ferrules pointed straight at the center of the hub. So all the spokes (x and radial) have some visible bending as the nipple is pulled so tight, the nipple stays perpendicular to the rim.

https://cimg6.ibsrv.net/gimg/bikefor...0b307da7de.jpg


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