Forks

Discuss the eternal "Which fork/bike/tyres should I buy?" questions.
Nerd_Thing
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Forks

Postby Nerd_Thing » Tue Feb 04, 2014 11:11 am

Hello all,

Just after a bit of advice, if possible, please? I currently ride a 12 yr old Specialized Hardrock A1 Comp. I'm more than happy with the bike and have no plans to change it in the near future. I've upgraded the brakes to Shimano SLX hydro discs, so it's good to go for a while longer.

The only things that troubles me slightly, is that I'm still running the original RockShox Judy TTs, which are beginning to show their age.

I plan to replace them, cheaply, and have been offered the following, all second hand: -

Marzocchi dj4
Marzocchi z1
RockShox j3sl
Rockshox Judy

I mostly ride XC around the Surrey Hill, so no mega jumps or massive downhills, covering 20-30 miles a time and around 100 miles per week. Given the choice (and they are all between £40 and £60) what would be the best replacement for me please?

Many thanks,

Hugh

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nicklouse
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Re: Forks

Postby nicklouse » Tue Feb 04, 2014 11:35 am

with out knowing more it is very hard to say. the Z1 might be OK as it is the best fork there. BUT it might also be compleatly unsuitable.

so fork years and version and travel are really needed.
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The Rookie
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Re: Forks

Postby The Rookie » Tue Feb 04, 2014 11:44 am

None of those are 'cheaply' at that price, that is more than any other than perhaps the Z1 is worth.

Of those the Z1 is the only one that is likely to be any better for you than what you have now.

Nerd_Thing
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Re: Forks

Postby Nerd_Thing » Tue Feb 04, 2014 13:00 pm

Thank you kindly.

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nicklouse
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Re: Forks

Postby nicklouse » Tue Feb 04, 2014 15:03 pm

but as said without more info it could be one of the crap ones or could be too much.

there have been 20-30 (or more) Z1 fork types made since 1999.
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G-S
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Re: Forks

Postby G-S » Tue Feb 04, 2014 20:44 pm

Never mind a new fork mate, a 12 year old frame (no matter how lightly ridden) is likely to be suffering from metal fatigue. I would look at retiring the frame too, not bolting new bits on it.

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cooldad
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Re: Forks

Postby cooldad » Tue Feb 04, 2014 20:46 pm

G-S wrote:Never mind a new fork mate, a 12 year old frame (no matter how lightly ridden) is likely to be suffering from metal fatigue. I would look at retiring the frame too, not bolting new bits on it.

As I am not allowed to use the word I normally would, all I can say is balderdash.
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Nerd_Thing
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Re: Forks

Postby Nerd_Thing » Tue Feb 04, 2014 20:51 pm

Built to last, not to throw away! :-)

G-S
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Re: Forks

Postby G-S » Tue Feb 04, 2014 20:53 pm

Call it what you will cooldad, but I retire a frame after 10 years max. It's up to you if you don't believe it, but frankly I've seen far younger frames snap for that reason.

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cooldad
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Re: Forks

Postby cooldad » Tue Feb 04, 2014 21:39 pm

As I said, balderdash. I have a Rockhopper that's well over 25 years old. The frame (and most of the other original bits) are absolutely fine. And a Hardrock from the early 90's. And a couple of other elderly bikes lying around, including a well over 10 year old Azonic, and even a Daewoo from the 90's.
Sometimes brand new frames break. Sometimes they don't.

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G-S
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Re: Forks

Postby G-S » Tue Feb 04, 2014 21:51 pm

Your choice mate. Not going to argue, but it's basic engineering as far as I'm concerned. I often see people walking through the trees carrying the wreckage of a bike, where a break in the frame has dark discoloration, usually the bigest clue that metal fatigue is to blame. A bloke I met at Keilder recently was carrying a 4 year old Intense frame which had broken at the head tube. The lad admitted though he had hammered that to be fair, however, I will stand by my 10 year rule if you don't mind.

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supersonic
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Re: Forks

Postby supersonic » Tue Feb 04, 2014 23:09 pm

it's really hard to tell with fatigue. My Zaskar LE frame was built in 1996. Best thing to do is check them thoroughly for signs ie striations and the like.

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Giraffoto
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Re: Forks

Postby Giraffoto » Wed Feb 05, 2014 11:06 am

I recall reading (admittedly a. a long time ago and b. with reference to road frames) that aluminium frames will inevitably succumb to fatigue. The life of the frame is determined by how strong it is in the first place, and how much strain it's put under. It still applies to structural parts of aircraft, so I'd expect it to be true of bike frames too. It's just a matter of figuring out how much strain they can take . . .
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The Rookie
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Re: Forks

Postby The Rookie » Thu Feb 06, 2014 05:06 am

Indeed, unlike steel aluminium has no fatigue limit, tap it with your finger tip enough times and it will fail (you'll be old and grey and have a very sore finger tip by then though).

That said, if designed and built correctly it's fairly unlikely to fail it by pure fatigue, much more likely that a single large input initiates a crack which then spreads through fatigue at it's tips where the stresses are massively higher.

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Kowalski675
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Re: Forks

Postby Kowalski675 » Fri Feb 07, 2014 04:10 am

The Rookie wrote:Indeed, unlike steel aluminium has no fatigue limit, tap it with your finger tip enough times and it will fail (you'll be old and grey and have a very sore finger tip by then though).


Probably best to alternate between different fingers.

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Giraffoto
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Re: Forks

Postby Giraffoto » Fri Feb 07, 2014 08:32 am

The Rookie wrote:Indeed, unlike steel aluminium has no fatigue limit


That's more or less how I understood it - whereas steel will just keep on bouncing back if you keep it within the point of plastic deformation (bending and staying bent, in other words), aluminium is getting fatigued a bit every time it flexes. This is why a steel valve spring can be bounced tens of millions of time in a car's lifetime, for example.
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The Rookie
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Re: Forks

Postby The Rookie » Fri Feb 07, 2014 09:06 am

Giraffoto wrote:
The Rookie wrote:Indeed, unlike steel aluminium has no fatigue limit


That's more or less how I understood it - whereas steel will just keep on bouncing back if you keep it within the point of plastic deformation (bending and staying bent, in other words), aluminium is getting fatigued a bit every time it flexes. This is why a steel valve spring can be bounced tens of millions of time in a car's lifetime, for example.


Close, but the fatigue limit for steels is below the plastic deformation, so you don't have to 'bend it' first.....


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