|   replacing a rigid fork with suspension | jerseyboy
Mar 28, 2003 6:49 AM | | I have an older GIANT bike that was top of the line in it's day, and still in excellent condition. I would really like to install a suspension fork, but the newer ones seem to be long enough that it would throw off the geometry (the standard fork is about 3 inches shorter than a friend's year old Judy fork). Does anyone have experince with an upgrade like this? Does anyone know of an older fork (I have seen a few on e-bay) that would have a length of about 15-1/2 inches from the drop-out to where the headset race sits?
-John |
| Couple of things.... | FreeRangeChicken
Mar 28, 2003 8:47 AM | | First, if you replace the fork, you need to know what size the head tube is on the bike. Most older bikes had 1" head tubes. Newer bikes, and therefore, newer forks have 1-1/8" head tubes/steer tubes.
Second, putting a suspension fork on a frame that was designed for a rigid fork can seriously alter the geometry of the bike, making it unridable in some cases. You will want to find a fork that is as close to the same length (axle-to-crown height)as the original fork as possible. This probably means a short travel fork (~64mm travel). If you go with an 80mm or 100mm fork on this bike it will probably look like a chopper and probably won't be able the keep teh front tire on the ground.
Good luck!
FRC |
| thanks for info | jerseyboy
Mar 28, 2003 12:27 PM | | FRC:
Thanks for the info. The steer tube is 1-1/8", so I'm in good shape there. I do not mind changing some components (like converting to an aheadset), but would like to keep the bike as stock as possible. I am aware of the geometry change, which is why I noted the length of the existing fork. I have not done the trig as to how much length would change the angle by how many degrees, but I think most would agree to keep it as close as possible to original. There are a couple of NOS forks on e-bay, and have requested a length measurement from the sellers to see how compatible they would be. But I just found this website and thought maybe somebody out there would have dealt with this issue before, even if was a few years ago when suspension forks were new to the market.
Again, thanks for your feedback.
-John |
| Another issue...... | FreeRangeChicken
Mar 28, 2003 1:04 PM | | There's a good chance that your old fork has cantilever style brakes on it. A suspension fork is likely going to require V-brakes. If I remember correctly, the brake boss position for cantilevers and V-brakes is different. Anyway, this may require you also to change your brake lever, or use an adapter device that will allow your cantilever brake lever to work with a v-brake.
QBP Travel agent:
http://www.performancebike.com/shop/Profile.html?SKU=2647
Just FYI info: 3" is a HUGE difference in forks. I made a change from a 64mm travel fork to a 80mm travel fork, which rasied the crown only 16mm or 5/8") and it made such a big difference I had to put the old fork back on. Not only does it change the steering characteristics, but it also changes the standover height of the bike. |
| You're good to go... | BruceBrown
Mar 29, 2003 7:17 AM | | JB,
I installed a suspension fork and a Thudbuster suspension seatpost on an older bike designed for a shorter length rigid fork. I would post a picture of it here, but I guess I am technically challenged trying to upload a photo from my Mac. Keep in mind, my wife did not want a new bike. She wanted me to update her old steel bike because she loved the women's top tube and saw no reason to get rid of it. So I did it her way. Only original thing is the frame. It's not the perfect solution, but she's happy with the way it rides. Because she weighs only about 110, we were able to set the sag and run the air pressure in the fork at a level which doesn't jack up the front end too terribly high. Steering is altered and handlebars are higher, so we had to counter with a stem and handlebar that would get her back to her familiar position of when the fork was rigid.
I put a 2001 Marzocchi Z4 Bomber on my wife's old Trek (was available with a 1" steerer). I just followed Mike T's instructions (thanks Mike T.) from his FAQ:
http://www.execulink.com/~dtierney/wmc/faq.htm
Used my own tools (no special ones required) to bang/tap out the threaded headset and to press in the new threadless one. Measured and cut the fork and installed it. Sure, the geometry raised the front of the bike a bit as I expected, but it is very much a worthy ride and doesn't suffer to much from the looking like a "chopper" syndrome. My wife gets her weight forward on climbs and to date has had no problem handling the altered geometry. The whole project took me an afternoon and the wife is happy as she now rides in a more confident manner.
It can be done and you can end up with a bike still worthy of a ride, but it is not going to be the "perfect" solution.
BB |
| thanks for info | BruceBrown
Mar 29, 2003 7:29 AM | | Edit |
| |
