Changing front fork to a suspension fork.

I bought my mountain bike in 1990, it was born before suspended forks were around and now I want to replace my front rigid fork with a new shock fork.

I looked on Ebay and there are a lot of forks have diameter of 1-1/8". I believe mine has 1" threaded fork and the head tube is about 5-7/8" (150mm) long.

I am wondering if it's possible to get a 1-1/8" threadless suspension fork and a new headset for 1-1/8" to fit on my bike?

Any suggestion?

Thanks all.

 

Unfortunately that will not work. You would have to find a fork with a 1" steer tube and the correct length/threaded length, and even then ,the geometry of your frame is most likely not compatible with a suspension fork. Instead of looking on ebay I would recomend taking it to a local shop and letting them have a look at it and possibly trading it towards a new bike (you can get a nice one for about/near the cost of upgrading your current bike).

 

ok, the 1-1/8" fork is not going to fit. How about if I get a 1" threadless fork with 1" headset, will it work?
Thanks

 

Well technically yes, if you found a 1" threadless fork and you changed over to a threadless headset(and you would need a stem)you could mount it to your bike. But there are other things to consider, the brakes on your bike are most likely center-pull with a cable stop somewhere inline--like on one of the headset spacers or possibly the cable goes through the stem itself (which like I said you would need to change) and most, if not all, suspension forks now do not have a stop on the bridge so you would need to upgrade to a side pull brake and brake lever to match. Even if you did all of the changes to the bike, it would not steer correctly. if you look at your current fork it probably has a very noticeable rake to it, in addition, your head tube angle is very steep. by putting a suspension fork on a frame that is not designed to have one you will drastically change the characteristics of how it handles. On some frames you can even get toe overlap from the front tire to the pedal making riding unsafe...
Just some things to consider---the cost of a new fork, headset, stem, brakes, grips (most likely damaged trying to remove) and all the time or labor costs, it may be better to keep that bike as a loaner to friends who want to go for a ride with you on your new suspended mountain bike. (I would buy a new bike)

 

Though the above posters have covered it off pretty well, I will add one more consideration. Putting on a suspension fork adds additional stress to the frame of your mountain bike, stress which was not designed for on your frame.

Specifically the head tube to down tube joint, and to a lesser extent the head tube to top tube joint and the head tube itself. It is even more of a factor on your bike, with the narrower 1" headset.

I would also suggest looking for a bike that was designed for a suspension fork that you can buy with a suspension fork already on it.

Cheers,
Juba