mtb - corroded front fork

[lph]

So, my lovely "real" mtb, a gift from my dh, is having trouble

The front wheel has a tendency to loosen under use. It seems to be because the dropouts on the front fork are corroded and pitted, causing the QR to not sit evenly and firmly. I'll add a couple of photos below.

My dh bought the bike lightly used and 1 year old, from a woman who had trained with it a couple of times and ridden one bike event with it (mostly gravel road, a little trailriding). I've had it for 2 yrs and not used it much, and mostly on the road, including a couple of weeks last winter. I noticed it starting to loosen last summer, but this year I've ridden some trail with it, and now it's very obvious. Using normal force to tighten the wheel there is still sideways play afterwards. The hubs are fine.

So I took it the store today, and they were going to ask Manitou, the manufacturer of the front fork. But they also said that it looked exactly the way it would have if I'd ridden with the QR loose. I haven't. I faceplanted off a bike at age 16 and very traumatically knocked out 2 front teeth, so if there's one thing I check religiously it's that the wheel is secure before riding. If the QR has been loose, it's loosened itself during riding. My dh is very nitpicky, so I cannot imagine him buying a bike used without checking something that obvious. I feel certain that this is a manufacturing failure, or that the metal is corroded from contact with salt from the roads.

But there's no way I can prove that no-one has ridden this bike with the QR not correctly fastened. Has anyone got any tips or any insight?

eta: on another forum someone who had seen this before agreed with my suspicion that salt is to blame, i.e. winter riding. But this hasn't happened to the other two bikes that I've ridden a lot more in winter

[Cataboo]

Ugh. That looks awful. What type of fork is it? (brand/model)

You should replace the fork for your safety, but I know that is an expensive proposition.

I'm not sure whether even if this is a salt/corrosion issue instead of a riding with the quick release loose - is that something that manitou should even address? The fork ends should be painted however

[Biciclista]

Perhaps it was like that when you got it?

[Cataboo]

if it's aluminum, salt wouldn't do anything to it. Perhaps it was like that when you got it?

Aluminum corrodes quickly in salt water. I've reached for the aluminum zipper on my life jacket before and basically had the zipper pull snap off.


What I mean by 2 metals touching each other & salt is:

http://en.wikipedia.org/wiki/Galvanic_corrosion

One key thing from that - is that magnesium is often used as a sacrifical annode...

[Cataboo]

Read this thread:

http://forums.mtbr.com/showthread.php?t=205320

[lph]

Well, I know winter riding demands more maintenance, but I've been riding all winter long for years without anything like this happening. More wear and tear, sticky cables, a little rust here and there, sure, but not massive corrosion like this. I've been riding steel and aluminium bikes. I think this is magnesium (it's a Manitou R7 front shock fork). It's been ridden maybe ten days on winter roads, not especially extreme conditions that I can remember. To be honest I feel that any bike should hold up to that, but if not, I feel that a warning with the fork would be appropriate. "This fork is extremely sensitive to salt and should not be used on salted roads", or something like that. It's been rinsed off regularly and parked inside, it's not like I left it out in a snowbank or dumped it in the ocean or anything

[Cataboo]

It may have to do with the metals that are used - If aluminum touches steel and you put it in salt water - you've basically made a battery and the corrosion happens pretty fast. I know if I'm kayaking in salt water, there are somethings that corrode within one or two trips - the zipper on my pfd, etc.

It may be the other bikes that you use in salt in winter either have different metals, painted drop outs or you're more meticulous cleaning the salt off. I don't know if the drop outs on that mountain bike fork are magnesium, steel or aluminum. Probably the shaft of your quick release is steel - the ends of the quick release are probably aluminum.

[OakLeaf]

It might be a manufacturing defect (poor alloy).

But salt does indeed corrode aluminum. Door frames, window screens, AC cooling fins, etc., only last so long on the coast, and salt air is to blame. I once ate the polish off of brand new polished aluminum hubs by riding the coast road - even though I washed my bike IMMEDIATELY after I got home, the damage was already done.

[lph]

It might be a manufacturing defect (poor alloy).

The specs for the same fork today just say "Leg material - 7050 Butted Al", which is aluminium I s'pose. Can this be an alu/magnesium alloy, with more or less magnesium? I should try to find the specs for my fork. It's from 2008.

The thread from mtbforums was interesting. I registered to see the photos, but I'm still not sure what an epi rocker is No matter. MOst interesting was that one guy had had no trouble whatsoever, and lived in an ocean environment, while others had problems galore.

[lph]

I know if I'm kayaking in salt water, there are somethings that corrode within one or two trips - the zipper on my pfd, etc.

Wow I'll keep an eye open for that.

I have to replace the fork anyway, because the bike is almost unrideable atm. I'm hoping Manitou or the shop will offer me a new fork, but I guess I'm not that optimistic either. I'm sure not riding that bike in winter again The disc brakes didn't like it either.

[Cataboo]

The handles on my stainless steel cooking pots will usually fall off quickly - the rivets holding them are some other metal and will just corrode away. I've had stainless steel cups split down the side (even though they were stored on the bottom of a stainless steel water bottle.

I've had a msr dragonfly cooking stove fall apart at the welds from exposure to salt.


I'm not always great about rinsing off my kayaking gear quickly after a trip, and I don't always think "oh, let's rinse the stove!" when the stove hasn't actually gotten wet or been immersed.

Salt water is just nasty.

I'm sorry you need a new fork. Hopefully you can make the case that manitou should have had those drop outs painted and sealed so that they weren't so sensitive to salt corrosion and manitou will at least give you a discount on a new fork. It's retarded suggesting that anyone would ride a mountain bike without the front wheel seated correctly, 'cause most people enjoy living.

I know I rode my carbon road bike once maybe a week after a snow storm - and sponged my bike down aftwards, but my brake calipers are all pitted & corroded from that one exposure. Now I just ride on the trainer and don't take any bike I care about in those types of conditions.

[lph]

It's retarded suggesting that anyone would ride a mountain bike without the front wheel seated correctly, 'cause most people enjoy living.

Yeah, I could feel myself go all prickly at the suggestion that that's what I'd done... Really! I did learn something from going through life with one blue and one yellow front tooth, and thinking at the angstfilled teenager time that "my skull is broken and I don't have a face anymore".