[xanderx918]

I have a somewhat old Cannondale mountain bike with no suspension and i was wondering if i could remove the stiff fork and put another fork on with somewhere around 120mm of travel on the frame. Could this be done without damaging the bike or frame and would it be worth it?

 

[rlouder]

You may be better off just getting another bike if you want front suspension. A suspension fork will raise the front of the bike. Besides adversely affecting the steering, some frames aren't designed for the increased force on the head tube joints.

If want to try it and can find a fork that will fit, stick with a short travel fork to reduce the effects I mentioned. Most people wouldn't choose a 120mm fork for xc riding anyway.

 

[AndrwSwitch]

It's already a XC bike. You're not converting anything, just bolting money to it in a way that probably won't improve the ride.

Give it a tuneup, the fattest tires you can fit between the stays, and go ride the heck out of it.

 

[Straz85]

Sure, you can put a suspension fork on it, but you need to consider the negative effects, mainly axle to crown length. This is the distance between the axle of the front wheel and the bottom of the steerer tube. It's usually shorter on a rigid fork than a suspension fork. They do make suspension corrected rigid forks, but an older bike probably didn't come with one. I would measure the A2C length on your fork and see what you can find for suspension forks with a similar one. If it were me, I would probably keep it within 20mm. The more you increase that measurement, the twitchier the handling of your bike will become.

 

[zebrahum]

Sure, you can put a suspension fork on it, but you need to consider the negative effects, mainly axle to crown length. This is the distance between the axle of the front wheel and the bottom of the steerer tube. It's usually shorter on a rigid fork than a suspension fork. They do make suspension corrected rigid forks, but an older bike probably didn't come with one. I would measure the A2C length on your fork and see what you can find for suspension forks with a similar one. If it were me, I would probably keep it within 20mm. The more you increase that measurement, the twitchier the handling of your bike will become.

Great post. I will add that I put a suspension fork on an old hardtail that was intended for 65mm travel fork. It was a 100mm fox float and even reduced to 80mm it handles very differently. I would suggest saving the money a fork costs and saving for a higher end bike. Unless you're getting a fork very cheap that can be adapted to the proper A-C measurement and like tinkering with things. Then it's worth a shot. Just remember that you need to get a fork that has the same brake mounts as you have currently or upgrade the brakes to whatever kind the fork accepts. So if you have canti brakes with a built in cable stop on the fork, then you'll need to get a new stop and a fork that is compatible with post brakes.

Also, you need to match the steerer tube length and diameter. Without knowing your particular bike model or age then worst case scenereo is that you will need to get a headset to reduce the headtube diameter (may be 1 1/4") to a modern size of 1 1/8". All speculation until we know what bike we're dealing with.

 

[xanderx918]

so basically i would be better off with just leaving the rigid fork on the bike because adding suspension won't necessarily improve the bike for the type of riding im looking for right? I do have some extra forks at my disposal so the money issue wont be a problem.

 

[jeffj]

Specifically what model Cannondale is it?

I don't know of any Cannondale XC frames that would likely be good to go with a 120mm fork, but if we know which model & year frame you have, it would help to get you pointed in a good direction.

Even a photo and a model would let us determine exactly what you've got there.

 

[zebrahum]

so basically i would be better off with just leaving the rigid fork on the bike because adding suspension won't necessarily improve the bike for the type of riding im looking for right? I do have some extra forks at my disposal so the money issue wont be a problem.

I think it's more accurate to say that putting a suspension fork on your bike will likely ruin the way the bike rides. But again, without knowing what bike and what year it's from we have no basis on what to suggest.

 

[AndrwSwitch]

If you've got some suspension forks lying around and you won't have to buy other parts, try it and see for yourself. Just don't charge on anything with compressions or bad transitions until you decide whether or not it's worth the risk to your frame.

 

[xanderx918]

The bike model is a Cannondale M300, The link here is the exact same frame and setup i have only the fork is a rigid fork as opposed to the one shown. as far as the suspension travel goes i realize that 120 mm is a little much but i do have a 75 mm fork in my garage. would that be more reasonable or could i get by with 100 mm of travel also? let me know thanks everyone https://media.photobucket.com/image...bikes/cottondaleburgundymountainsuspensio.jpg

 

[jtmartino]

The bike model is a Cannondale M300, The link here is the exact same frame and setup i have only the fork is a rigid fork as opposed to the one shown. as far as the suspension travel goes i realize that 120 mm is a little much but i do have a 75 mm fork in my garage. would that be more reasonable or could i get by with 100 mm of travel also? let me know thanks everyone https://media.photobucket.com/image...bikes/cottondaleburgundymountainsuspensio.jpg

Your idea is not going to work. Primarily because 120mm suspension forks don't come with 1" threaded steertubes. Even if they did, adding a longer fork to your frame will result in an absolutely horrible ride and a high probability that the frame will break.

It's a really bad idea all-around. Sell everything you have and buy a early 2000s used hardtail with a 100mm suspension fork and call it a day.

I should add that it's an entry-level bike with an entry-level frame that's not known for its ride quality. Either throw fat tires on it, or get a new bike. Seriously.

 

[brent878]

I did exactly what you are trying to do. I took a 1992 GT and put a 125mm rockshox on it. I love the way it handles now, the HA was way too steep stock for the riding I like to do. It does put alot more stress on the headtube but been riding it for the last 7 years like that and has held up well. But mine is a Ti frame so I wasn't too worried about that aspect.

But you have a bigger problem. It looks like yours might be a 1" steering tube. If that is the case you basically have no options for a new suspection fork. I think there might be one or two compainies making them but those are probalby going to be disc brake only. Which would mean you need new brakes, new wheel, new forks, new stem, new headset, and possibly shifters. I had to do the same thing and just replaced everything but the frame. If it wasn't an expensive Ti frame I was starting with I would have just bought a different bike. I spent the same amount of money.

Best bet would be to find a newer used bike for the money you were gonig to upgrade with. And I know you said you had some forks lying around you could try, can you post those forks up and we'll see if you can just bolt them on. Unless those forks you have are setup for cantilever brakes you are going to be spending some money to get it working.

 

[IamSkidder]

xander,
What did you end up doing?