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Old 01-20-14, 08:11 AM   #1
idc
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MTB fork lifespan

Hi,

I have a 2005 GT Avalanche that I've used mostly as a beater bike/snow commuting, and I'm wondering if the stock fork needs replacement. It's a SR Suntour XC60.

When I lock the front brake, and rock the bike, the fork bends in the stanchions. The rubber cover over the stanchion also doesn't go back down on the left side, and it's pretty squeaky.

The bike has maybe 1500 miles on it, if that. Very little offroad riding.

Last edited by idc; 01-20-14 at 08:14 AM.
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Old 01-20-14, 08:51 AM   #2
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inside suspension forks are wear items that need to be periodically replaced
the problem is
most fork manufacturers do not sell parts for forks more than two or three years old
and some of them sell no parts at all

also
the makers of more expensive forks
reccomend frequent matintenance
like possibly every 100 hours of riding or so
which might be once or twice a year for frequent riders
and lack of maintenance will surely hasten the wear of parts

and
using a bike as a commuter
especially in the winter
is just about the worst thing you can do to it
wrt wear

when considering maintenance or replacement
you should know that
the suntour forks have always been basic entry level stuff
not bad
but not family heirlooms either
so i dont know if parts are readily available

if you can find new bushings and wipers
then a rebuild will almost certainly make it better

if parts are not available
then see if you can find a manual or exploded drawing views
and take the fork apart
and clean and lube the internals
and see if it doesnt improve the function somewhat
although it is unlikely to improve the back and forth play you described

otherwise
it it probably time for a new
or lightly used
fork

nine years is a long time for mtb parts
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Old 01-20-14, 08:57 AM   #3
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Thanks yeah, I have been planning to replace it with a rigid fork for some time but it's low priority as long as the fork holds up - which it now doesn't quite seem to be.

Is it dangerous to ride on a fork in this condition? Am I tempting the fates?
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Old 01-20-14, 09:04 AM   #4
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Suspension fork "life' is part mileage, part exposure to elements and part maintenance. A lower cost fork (as the ST is at this bike's price point) also suffers with lesser seals and bushings. In fact many new low cost forks will have more slop (i use this tern instead of flex, to me flex is the bending in an otherwise solid unit. Slop being the movement between two units.) then an older well made and maintained fork. So there's a lot of subjectiveness. Basically when you no longer are happy with the fork's performance (whatever that means to you) it's time to consider something else.

If the seals had been periodical opened (I use a sharpened spoke to slide between the seal and the leg) and lube dripped in. If the stanchions had been removed from the legs and cleaned out then relubed with a fork grease. If the forks had seen little wet then they would be in better condition then they seem to be now. Most riders never do this maintenance. Most rarely even wipe off their bikes.

Where has the OP's service/care been within this range? If you have been really taking good care of the fork (as described) and it is still sloppy/loose then you would find a high grade fork MUCH nicer. If you have not been caring for the fork very well at all then even a mid grade one well taken care of will likely make you happy for a lot longer time.

Do understand though the manufactures consider a fork to be a wear item. Many don't even offer replacement parts (seals, bushings, O rings) past a few years for any given series. Andy.
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Old 01-20-14, 09:08 AM   #5
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Quote:
Originally Posted by idc View Post
Thanks yeah, I have been planning to replace it with a rigid fork for some time but it's low priority as long as the fork holds up - which it now doesn't quite seem to be.

Is it dangerous to ride on a fork in this condition? Am I tempting the fates?

Generally the failure mode for suspension forks is a slow increase of slop and a lessening of the suspension travel. Both are not events that prevent the fork from steering the bike in an instantanious moment. But do take the worsening condition as the sign of replacement being in the future. I suspect that a rigid fork will ride/steer a lot nicer for your commuting. Andy.
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Old 01-20-14, 09:12 AM   #6
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Thanks Andy. Mostly I'm just worried of a catastrophic failure. Something snapping (stanchions I'd guess, since the lower legs seem very solid). If that's not really possible, I'm fine riding it until I get around to replacing it.

I have other bikes I put a lot more mileage and maintain properly, but I only really oil the chain and replace brake pads as necessary on this bike. And it's stored outside (others are all stored inside).
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Old 01-20-14, 09:19 AM   #7
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Quote:
Originally Posted by idc View Post
Thanks yeah, I have been planning to replace it with a rigid fork for some time but it's low priority as long as the fork holds up - which it now doesn't quite seem to be.

Is it dangerous to ride on a fork in this condition? Am I tempting the fates?
It sounds like the bearings in the slider are worn. This will cause a knock in the forks as you brake and will make the steering somewhat sloppy. It's more annoying than dangerous but you should address it sooner rather than later. In the mean time, keep any off-road riding to a minimum.

On the replacement with a rigid fork, that might not be the wisest idea considering what you want to do with it. I recently had cause to test a rigid (locked out suspension fork, actually) against an active suspension fork in a good snow storm. When the fork was rigid, the front wheel would dig down into packed snow and pull me off line. I also noticed that the bike tended to drift down off the crown of the road towards the gutter. When I made the shock active, the front wheel no longer dug into the snow but floated over it. The bike became much easier to handle and quit drifting down towards the curb.

I'd suggest looking for a used Rockshox or Manitou air suspended shock. Both have a lockout that the Suntour lacks that let you ride rigid when you don't need suspension but let you open the shock up when you do. The Rockshox's lockout isn't a positive, in my experience, as the Manitou's however. I can easily make a locked Rockshox move but the Manitou is rigid when locked.
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Old 01-20-14, 09:25 AM   #8
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suspension forks seldom snap in half
and if they do
it is almost never related to play or slop between the lower part
or sliders
and upper part
or stanchions

the only possible relationships i could think of between the movement you describe
and catastrophic failure

would be
if the play is actually due to loose fasteners that should be keeping the sliders from sliding off the stanchions
and one day you tried to pull a wheelie up onto a curb
and your fork came partially apart and you lost control
or
if the play was actually not between the sliders and stanchions
but was a crack in some structural part of the fork
and you misidentified it
but i cannot think of an instance where i ever saw anything like either of these scenarios

however
if you were to disassemble
inspect all parts
and reassemble
then you could be sure

but i agree with the lovely and talented andypoo
that a new 30 dollar rigid fork will not only fix your fork insecurities
but also make the bike better all araound
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Old 01-20-14, 10:20 AM   #9
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Ok sounds good. I don't ride this bike much on anything other than commutes, or towing a trailer, etc. so it sounds like the fork will be safe enough for that.

I have been considering getting an actual MTB for trail riding, which would have a working MTB fork. That way if I don't like a rigid replacement for this bike I could have a MTB for snow riding. We'll see.

Also - where can I get a $30 rigid fork? (26", QR).

Thanks all!
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Old 01-20-14, 11:00 AM   #10
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Quote:
Originally Posted by idc View Post
Also - where can I get a $30 rigid fork? (26", QR).
http://www.cambriabike.com/Rigid-26i...26in-Wheel.asp
for example

call your lbs and they my have something or be able to order something similar for a similar price
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Old 01-20-14, 11:03 AM   #11
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Ah, forgot to mention I need a disc fork. I swapped to a BB7 upfront a few years back for the winter.

I will talk to the LBS though, they're good people.
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Old 01-20-14, 11:16 AM   #12
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Ah, forgot to mention I need a disc fork. I swapped to a BB7 upfront a few years back for the winter.

I will talk to the LBS though, they're good people.
might be a bit more for disk compatible
online they start at 50 to 60 bucks
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Old 01-20-14, 06:04 PM   #13
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IMO for a winter/beater bike the only thing I'd ever use is a rigid fork, or maybe an old disposable suspension fork if I had to. Winter commuting will destroy a suspension fork as you've seen. I have no problems riding through snow on my rigid MTB or my rigid cross/commuter/hybrid. No problems that would be solved by a suspension fork anyway. Just use the fattest tires you can and run them at appropriate pressures. Your new rigid fork will be lighter (a LOT lighter replacing that Suntour) and more efficient pedaling when the pavement is clean.
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Old 01-20-14, 08:37 PM   #14
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Thanks, yeah this fork is definitely not doing too well. I have a disc brake CX bike I use in light snow too and I haven't missed the shock there.

It'll get a few last run throughs this week though.

Incidentally, is there any issue putting a 26" front wheel in a CX bike? I did some calculations and with my 26x1.9 studded front tire the BB will only drop maybe 1cm at most. It fits fine too, I've tested it and the 160mm rotors line up pretty closely.
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