Is it possible/sensible to add a suspension fork to an old mountain bike?

Question

I have a ~1993 Giant mountain bike. It's not great, but I am a very new and casual rider.

The bike has a solid fork and it makes for the predictable rough trail ride. The trails are generally fairly modest (I live in North Texas, a 100' change in altitude makes our ears pop here) and the surface is generally dirt (very few rocky areas).

So, I am thinking that it would be very nice to have a suspension bike. And seeing that a modest fork can be purchased for a modest price, I am wondering if it makes sense to add a fork to this bike.

This question asked about going the other direction, and there were some cautionary words about changing steering geometry.

So, on balance, is this something that I would be best off to avoid? I suspect that if I have to replace a bunch of steering parts, the cost will quickly approach that of a new low end bike.

Answer 1

I would consider looking at a used later model bike. The improvements made in the last 18 years are worth the money. A decent fork can run hundreds of dollars, not including installation. Check with your local bike shop for used bikes or Craigslist if you keep it local so you can see before you buy. Bikepedia is a good reference to make sure you have an idea what the bike cost new.

Also check the minimum inflation recommended for your tires and run them softer than you have been. This will cushion some of the bumps. An alternative might be to install the biggest 26 inch tires you can fit in your frame and lower the tire pressure to get more shock absorption.

Be careful of really low-end bikes from the big box stores (Walmart etc.). A really cheap shock with no dampening or adjustment is worse than no shock at all.

Answer 2

One of the main problems with converting an old bike is the width of the headset. Old rigid mountain bikes[1] commonly have a 1" headset while modern suspension bikes have a 1 1/8" diameter headset. Suspension forks are mostly for 1 1/8" headsets so fitting suspension to an old rigid mountain bike is normally a non starter for that simple reason.

The geometry is another good reason and may in fact be part of the reason that bike manufacturers decided to use the different diameter, to prevent the conversion of bikes that weren't designed to bounce. It may also be that with the wider tubes they can take more load allowing the bikes to take more of a beating. Of course it all could be a conspiracy to take our money, but honestly, I think the technology has just changed.

In general I'd recommend keeping the old bike for getting about and getting a newer bike for doing the more hardcore stuff. Brake technology has improved dramatically, the bike frames are built stronger and lighter, and the gears generally shift smoother and more reliably. And that's trickled down quite nicely to the cheaper bikes too. There is a limit to how cheap you want to go for doing proper off road, but you don't have to spend too much.

[1] Note that there are still new bikes manufactured with 1" diameter headsets, but they are normally cheap rigid bikes.

Answer 3

I'd suggest that you might be happier with a pair of "suspension tires" – find the biggest tires that will fit, you'll be able to run them at relatively low pressure which will give you a decent amount of suspension.

If you've already got large tires on the bike, then check the pressure – you may be running them with too much pressure, with something like a 26 x 2.0 tire you could probably run something like 30-50 psi / 2.5-3.5 bar. These pressure charts from Schwalbe and Bontrager will give you a better sense of the range.

Answer 4

The above answers are correct and the tread is now as old as the topic (almost). But they do make 1" suspension forks - and you can find an upscale one from about $70. A bigger question is whether it's worth it based on the selling price of the result - there is a good reason why this doesn't matter. Some earlier model bikes that you can pick up for literally $20 if you have eagle eyes and frequent yard sales, have a frame that is worth more than $100 if you strip all the parts off. Those would be high-end Japanese cromo double-butted (or triple-butted) that are literally 3X stronger than aluminum and only about 3# heavier. The equivalent frame on the cheapest new MB will set you back $1500 as of 2015. Two or three more things - there is the panache of having an old Giant Iguana like mine. They actually have a glass coating instead of paint, which is unique for that factory. And, after doing the research and riding a like-new example with the usual upgrades - I would not dream of wanting to slap on another 15 pounds on the front end. That's especially critical when riding in shallow soft sand - the balance has to go to the rear. Because of that fork, this bike is wonderfully maneuverable. But it will jar your teeth on hard washboard or worse. (Solution: more bikes!) The DB cromo frames themselves are flexible, unlike the oversized aluminum tubes. It gives these old bikes a very subtle "aliveness" that aluminum - no matter the price - can never have. Expensive MB's feel solid - but underneath that feel distinctly dead to road (and sidewalk) feel - missing that "old track-bike" feel.

Also, very important, I don't worry as much when I park it in front of the store. It's "worth" less than a new Wallymart sprung special "and everyone knows it." They don't have a clue about this stuff, until they hear me ring the frame (they ring like a bell) and hear about that glass coating.... And of course those frames will survive welding, will keep threads, and won't crack or bend as easily.

Very cool.