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 :confused:

[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?

[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 :rolleyes:

[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.

[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...

[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.

[Cataboo]

Read this thread:

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

[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 :eek: 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 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 :D 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]

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". ;)

[lph]

I have to buy a new fork, but the shop is giving me 20 % discount on a new, and cheaper fork. Manitou has not been involved.

According to the shop "Manitou couldn't take all riding conditions everywhere" into consideration, so my suggestion that designing a fork that is useless in winter is a bizarre thing to do fell flat. The shop apparently warns people against using these bikes in winter, so they're covered.

Agh. Makes we want to go all technophobic. Just make something that WORKS, dammit, don't mess around building something 40 grams lighter that can only be used half the year, if you don't sweat, in the high frigging desert.

Sorry. It just pisses me off when my everyday, ordinary, sensible use of a bike for transportation is somehow seen as a very strange and "special" thing to do.

Lesson learned: do not use magnesium ANYTHING on a salted road!

[OakLeaf]

Ugh. That's not only stupid, it's insulting.

They would never get away with that with a motorcycle - even though a large majority of motorcycles are only ever ridden in dry weather without salted roads, and even though in the USA they're mostly ridden for recreation and not transportation.

The only relevant differences IMO are that new moto forks cost more than new bici forks (of equivalent performance), and the riders are stereotypically more likely to be assertive.

I'd be furious.




ETA - I've actually owned two motorcycles that were poorly designed for wet weather riding. Both of the flaws were serious in their own way and could be bad for someone who didn't know about them ... but both could be easily and inexpensively fixed by drilling and/or enlarging drain holes.

[Cataboo]

is it a bike shop you use regularly or are attached to? Because I know you do your own bike work. I'd be insulted enough at that suggestion & response, that I would just take my business for the fork elsewhere.


Check out the US websites or the UK ones and see if you can get a better discount than 20% on a fork for the bike - and order your own (let me know if you can't get it delivered to Norway, you can use my address & I'll mail it on to you)

Mountain bike forks are expensive.

[lph]

I think maybe a question to Manitou is in order, pointing out that magnesium is maybe a mite fragile and should come with whopping huge warning labels in the North European market.

It's not a shop I like or use. Large sports chain. I'll check prices a bit and see if it's worth the effort to order a new fork somewhere else (thanks for the kind offer, Cat!). But I'm def taking the bike home to install the new fork myself rather than pay them to do so. I've given up on fixing the rear brake myself, but that goes instead to my favourite and very trusted lbs even if it means I have to wait some weeks because everybody else in town also has them as their favourite and trusted lbs and it's race season. I may have to pay a bit more, but head wrench will then tell me afterwards what he did and why, and they won't try to make me feel like a blithering idiot for having the temerity to ride a "lightweight bike meant for training, not commuting" in winter.

Oak: ah, but motorcycles have motors, just like cars! And cars, as we all know, are what you're meant to use out there! :mad:

Ok, I'm even pissing myself off here ;) Time to go eat something and head home.

[lph]

Happy update! Head honcho of sports chain store in question has seen the photos, and agrees that the corrosion was really pretty bad. New solution - they have a fork or two knocking around with broken insides, so I can inherit the outers. Right colour too, so this is a great solution all round - I get a working fork, a broken part gets a new life. Perfect :)

[Cataboo]

Excellent. YOu should still send a note to manitou :)

[lph]

(I refrained from asking why they had multiple forks knocking around with broken insides... ;))