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Quick question. I have a lower quality mountain bike with a bad suspension fork. Overall the bike isn't bad. It fits me well and I have a lot of fun on it. I would like splurge on a new mountain bike but that just isn't a priority right now (but a cross bike would be pretty nice...).

So I was thinking that maybe what I should do is look around for a new fork. My general bike knowledge is pretty good but I know almost nothing about forks. I was hoping that someone could point me to a good reference on what I need to know before I buy a fork.

I think that buying a new fork probably isn't a good deal. I think for that price I should just buy a new bike. I would ideally like to spend around $100 but I would spend up to $200. I suspect that this puts me in the used fork category.

Key features I would like out of my new fork:

  • Cold weather riding: my fork currently goes stiff at 5C
  • Lighter
  • Better traction/handling
  • More fun
  • Other - I have never ridden a better fork so "other"

Links:

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Is it a brand name bike that would lend itself to being upgraded?Is it threadless or threaded?How much travel on the orignal fork?About how old is the bike? –  mikes Mar 1 '12 at 22:18
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If you only have $200, I wouldn't bother upgrading the fork. –  Mike Baranczak Mar 2 '12 at 1:39
    
Do you want a list of references about forks, or knowledge to help you choose a fork? (If the former, this is a list question.) –  Neil Fein Mar 2 '12 at 4:35
    
What kind of riding? –  cmannett85 Mar 2 '12 at 7:37
    
Would a SUSPENSION fork (= FUUUNNNNN!!!!) be an option? –  heltonbiker Mar 2 '12 at 11:47
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2 Answers 2

One of the most important things when you put a fork on a bike is how it "fits" the bike's frame geometry. Ideally fork and frame are designed together in what is called a "frameset". The geometry, which difectly determines fit and handling, is only complete when you consider a frameset, not a frame alone, neither a fork alone.

Nowadays, many mountainbikes are designed to be used with a suspension fork with relative large travels, for example 100mm. Then, if you take a rigid bike and put a suspension, you'll lift the bottom bracket, decrease the seat tube angle and decrease the head tube angle, unavoidably altering fit and handling.

Also, if you take a frame that's supposed to run a suspension and install a (shorter) fork, or even a shorter suspension, the same effects happen in the same way. That's why Surly (a manufacturer) produces "100mm corrected" framesets, which consist of a frame ready to receive a suspension fork, and a fork substantially longer than needed (about the same size of a 100mm suspension fork.

I have already made both changes (lifting and lowering the front-end of a bicycle via exchanging suspension or fork). The result in terms of rideability, when the bike is not "ready", is always a bit awkward.

Talking about fork materials and rigidity, from my experience rigid forks from any material are pretty rigid, to the point you cannot actually note any difference. Some steel forks have wide curves close to the dropouts, in order to absorb some shock, but that's a very old-fashioned design, and would look definitely "wrong" on a mountain bike. Mountain bikes should absorb shock via a suspension-fork, or wide tires, or both.

A side effect of some suspension forks is that handling becomes a bit wobbly either because of torsion/deformation of the fork itself while steering/cornering, either because of altered handling geometry (raising the front increases caster, making the bike potentially "slow" to steer).

I have seen broken forks, and have broken/bent some cheap ones myself in the past, but I think any decent one (in your price range) would be fine. Aluminum ones are probably lighter and very well suited to your intended use. You just should choose one that has at least a similar geometry to your current one, specially if you like the way your bike handles and don't want to spoil that.

Hope it helps.

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Well, I finally looked at the photo, and seems to me you were talking about suspension forks all the time. Well, anyway, these are my points of view regarding, mostly, rigid forks. –  heltonbiker Mar 2 '12 at 15:11
    
Thanks for the answer. I am interested in replacing my suspension fork with another suspension fork. My understanding is that if you exchange a 100mm suspension fork for another 100mm suspension fork it should not change the handling of the bike. Agreed? –  sixtyfootersdude Mar 2 '12 at 18:04
    
@sixtyfootersdude agreed, except for two facts: 1) the fork might have a different fork rake; 2) the fork might have a different crown-to-axle distance OR have a different initial ("sag") position. I would strongly recommend not spending too cheap on a suspension, otherwise you will waste time and money and not necessarily get a good product. In the world of hydraulic-low-friction-anodized-super-plushness, things cost what they're worth. –  heltonbiker Mar 2 '12 at 18:18
    
@heltonbiker What's a fork "rake"? –  cmannett85 Mar 3 '12 at 15:08
    
@cbamber85 it's the distance the centerline of the front axle goes ahead of the centerline of the steering tube. This positions the front wheel in a way that stabilizes the bike, and can be changed by manufacturers to fine-tune the bike's rideability. –  heltonbiker Mar 4 '12 at 1:46
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The bad news

$200 won't get a new fork much better than the one you have now.

The good news

The second-hand market is full of a couple of year old forks that were originally twice that.

Do your research

Forks may look frighteningly full of tech, but they are designed to be serviced so the delicate parts are inside cartridges that can safely be removed. So if you see a fork you like on eBay for example, go to the manufacturers website and look at the servicing instructions - it will make your second-hand fork feel new again and only for the cost of new seals and some fork fluid (~$30).

Play it safe

  • Stick to the 'big 3' manufacturers: Marzocchi, RockShox, and Fox.
  • Do not go beyond 4 years old.
  • Remember to ask the seller what length their steerer tube is, it's normally cut down to fit the bike - but if their headtube is significantly smaller than yours you may have not enough material for your stem to bite onto.
  • Ask the seller if there are any scratches/dents on the stanchions (the smooth poles the seals grip onto), if there are - DO NOT BUY!
  • Ask the seller if the forks creak, it generally means the bushes need replacing. Although this isn't too difficult, it will add ~$30 onto the servicing cost.
  • Finally, read reviews on your chosen fork MTBR is a good place. And once you have any specific questions, come back here and we can help.
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So for a new fork what would you recommend spending? Do you have a specific fork that you could recommend me as a "buy this or better"? –  sixtyfootersdude Mar 5 '12 at 14:23
    
I can't answer either of those questions; I don't do XC riding, so I don't know enough about fork models that target that market to give any decent advice. And what I recommend spending has little or no relevance to you - because I don't know how seriously you take it, how much money you're realistically likely to spend, etc. Also money will only determine so much, my forks cost $1300 or so - and I think they're naff. –  cmannett85 Mar 5 '12 at 16:27
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