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Cheeto 02-03-08 03:01 PM

is it..
Possible to get a 100mm fork for my Trek 3900?
it came with a 80mm, but im wondering for when i start looking to upgrade stuff when I get my J-O-B lol.

RIC0 02-03-08 03:23 PM

yes a 100 will work, I've used a 100 on my Trek 4300 in the past. The frame will only support 100mm and nothing bigger.

nickj6 02-03-08 03:38 PM

yea im looking to get a 100mm too for my 3900.

pyroguy_3 02-03-08 04:49 PM

Originally Posted by RIC0 (Post 6102280)
The frame will only support 100mm and nothing bigger.

Not true, you need to look at the total length of the fork, crown to leg. On the right track though RICO. I changed to a 130mm from a 100mm and the overall length difference was negligible.

EthanYQX 02-03-08 05:17 PM

You can do it, but you need to check the A-C height.

Cheeto 02-03-08 07:24 PM

You all are speaking above my level lol!
So like what forks will work?
Cause 80mm isnt enough for me. if i hit a big enough root or dip i bottom out.
--- Im only 165 lbs so dont call me fat LOL.

Now another question while I have everyones attention.
Is it normal to have some play in the neck area?
Like when i hit my front brakes and move the bike forward i can feel the fork wiggle inside the neck.

I made sure the bolt was tightened all the way, and it still has some play.

EthanYQX 02-03-08 07:43 PM

Noooo. That's not good. I'd get that checked. Hints at a headset issue. Should be warrantied.

As for the fork, when you check the specs on a website the measurement you need should be listed as "Axle to Crown height" or something resembling. Find out the A2C on your stock fork, and see that it matches. If you're buying from a LBS, even better. Tell the employee what you have and ask them to check the A2C. You can also ask for a list of forks that will work if he finds you the A2C

Cheeto 02-03-08 07:57 PM
i believe thats the fork i currently have.

just mines blue.

ever since i got the bike its had that tad bit of wiggle in it, So, im guessing i should take it in to get looked at?

EthanYQX 02-03-08 08:06 PM

Yes, defenitely take it in.

A2C is not listed, odd.

EDIT: On second thought, email them here:
Ask for the A2C of that fork, link to it if nessecary. If they have any type of customer service they should tell you no problem.

Cheeto 02-03-08 08:09 PM

any one know about the adjustments on that fork?

on the adjustment knob theres a little clear area with a yellow bar in it with red lines.
when i turn the knob, the yellow bar does not move.
I figured that if i turn the knob the yellow bar should go up and down...

EthanYQX 02-03-08 08:11 PM

Ask about that too when you bring the bike in for the clunking, if no one else weighs in.

Your LBS gives you a warranty for a reason. I was there every day for two weeks after I got my last bike.

Cheeto 02-03-08 08:26 PM

Its such a pain to go the whole way across town though LOL>

EthanYQX 02-03-08 08:27 PM

Set a day aside and make it a ride.

pyroguy_3 02-03-08 09:48 PM

You should be checking the bolts' torque every once in a while. Especially when it is a new bike. I check the bb cups, crank bolts, headset, etc. every month-2 months depending on if I have time or feel like it. I did ruin a bb because the cups worked loose. I didn't have the right size crank puller so I just forgot about it until I burned the bb out. I also had the headset looseness problem. Unfortunately I learned from experience that a loose headset can ovalize the headset. Also, it may just be the fork stanchions having play between the lowers. Also, if you had a better fork it probably wont bottom out on you. There isn't much adjustability in a lower-end fork. Upgrades are wonderful!

BenLi 02-03-08 11:22 PM

Originally Posted by pyroguy_3 (Post 6104164)
Also, if you had a better fork it probably wont bottom out on you. There isn't much adjustability in a lower-end fork. Upgrades are wonderful!

Agreed. The fork bottoming out is not an indicator you need more travel, but more adjustability within the travel you already have. That said, I would still make the jump up to 100mm.

ProFail 02-04-08 12:16 AM

Originally Posted by Cheeto (Post 6103779)
Its such a pain to go the whole way across town though LOL>


Anyway, to state what already has, as long as the leg length is similar to your 80mm fork, you should have no problems.

Cheeto 02-04-08 06:24 PM

does anyone know what the height is for an 08 trek 3900?

19.5 frame

pyroguy_3 02-04-08 06:46 PM

Originally Posted by Cheeto (Post 6109131)
does anyone know what the height is for an 08 trek 3900?

19.5 frame

The length of the fork? The standover height? For the length of the fork: take a tape-measure and start from the bottom of your headset, where the fork goes through the frame, and measure to the dropouts on your fork, where the axle passes through the fork. This should give you a fairly decent measurement. Might want to take the wheel off so as you can go straight down the center of the fork in your measurement, otherwise you get a little longer measurement due to the angle. Maybe also take the measurement from the top of one side of the crown to the bottom of the leg. I'm not sure what the companies base their measurements on. Anybody?

Cheeto 02-04-08 07:02 PM

trying to find the so called A-C height thingy.
the more i think about my fox the more it pisses me off and the more i hate it lol

pyroguy_3 02-04-08 07:11 PM

The AC height is an acronym for Axle to Crown height. It's basically outlined in what I posted in #18. You really only need a tape measure. It's not something where they have to be exactly the same, maybe within 40mm? Usually it's better to go longer than shorter, for me at least. I like a more stable steer, while going shorter would make the steering easier to turn basically. Kind of like raking out the front of a motorcycle really far and slapping apehangers on it. Those guys can't turn for ****.

Cheeto 02-04-08 08:58 PM

Does anyone have any ideas as to which fork i should start looking into?
I have a 3900, so I wont be doing any Dirt Jumping or that crazy downhill stuff.
Just some normal mountain bike trails, and maybe some XC type stuff.

preferably 100mm.

i measured from the to of the fork, where it goes into the headtube thing, to the bottom,
its about 17 inches.

Anyone have any ideas on a half decent fork that actually works? lol

EthanYQX 02-04-08 09:04 PM

Check out Marz. Find something close to a 17" A2C. Maybe a RS Dart?

pyroguy_3 02-04-08 10:13 PM

What is your budget? Sorry if you posted it already.

Cheeto 02-05-08 06:10 PM

Ehh, I don't have a set budget.
Cheaper the better.

I mean, Im not paying 250 for a fork, as its more than half the price of the bike.
Ill go maybe no higher than 120-150ish.

(anyone have any good used ones? LOL)

Cheeto 02-05-08 06:16 PM

what would i be classified as?
Cross country or all mountain.

Id imagine XC, as thats what type of fork the bike came with even though its cheap as crap.

BTW took my bike into the shop today, well, my dad did, and they fixed my wiggle problem. =)

EthanYQX 02-05-08 06:21 PM

It's somewhat XC. XC when used on a low-end fork means "light trail or road", basically. Too heavy to race with, not set up to jump or drop with.

Cheeto 02-05-08 06:29 PM

Well, Ive been offered a chance to start training with racers and members of SORBA, One of my teachers is a member and asked if I would like to start doing some racing.
So, I'll be upgrading quite a bit this summer..

--- geeze, I need a job.....
Just need some help on the forks because BMX bikes didn't have suspension, I'm new to all this, and I'm openly admitting, I don't know much about suspension forks, except that mine sucks.

pyroguy_3 02-05-08 06:35 PM

Pretty much anything over $100 is going to be better than the one you have now. However, this is not saying much. My fork cost about 100-200 more than my bike originally did, but it's worth the money. If there is one place to spend money on a bike it's the suspension. Then the brakes. In my opinion, that is.

EthanYQX 02-05-08 06:37 PM

Ride the hell out of the Trek, work hard, get a decent job. Build up a real XC bike. By "real" I mean a weight-weenie, quasi-roadie special. Good luck.

Cheeto 02-05-08 06:45 PM

I'm not a moron crankshaft, i know what you mean by real.
You can quit treating me like a little kid any day now.
Thanks for the input pyro.
Starting to like some of the Marz. forks, but they don't list prices.. that scares me.

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