Checking for bent forks

snapcasezx3 · Posted: March 2, 2009, 1:27 pm Post subject: Checking for bent forks

I hit some gravel and ended up dumping my bike. I wasn't going very fast (<25mph) and had only cosmetic damage. However, I want to make sure that my forks aren't bent and that my alignment is fine. How can I test for these things? I am hoping I don't have to take it to a mechanic, because I have done everything on my bike myself so far. Thanks.

yamaman · Posted: March 2, 2009, 1:43 pm Post subject: Re: Checking for bent forks

The most correct way to check if a staunchion is straight, is to remove it and roll it on a dead flat surface (a sheet of glass works). Roll it a tad, measure with feeler gauges, roll some more measure some more & so on.
If it's not to bad it can be straightened, it's obviously not to bad as your not sure if it's bent!
Good oportunity to replace that 30 year old fork oil anyway!
Really though, if you push down as hard as you can on the bars and feel no stiction, then they are probably ok!
Cheers

pamcopete · Posted: March 2, 2009, 2:02 pm Post subject: Re: Checking for bent forks

snapcasezx3

The triple trees will bend just as easily as the forks. You have to remove them and place them on a flat surface to see if there is any distortion. Here is a pic of a bent lower triple tree.

In this particular incident, the forks were not bent, but the handle bars pointed right when the wheel was straight ahead, which is the real test for anything bent in the front end. The handle bars will not line up.

You can also use a laser level held to each side of the rear wheel to form a beam that should be equa distant from either side of the front wheel. This test checks for overall alignment, including a bent frame.

Regardless of whether the forks, triple trees or frame is bent, the handle bars are more likely to be bent.

If the bike fell on the right side and the brake lever hit the ground, then another possible damage area can be the master cylinder and/or the brake lever. The master cylinder can be internally damaged by the sudden high pressure produced when the brake lever hits the ground. I had a brake lever break off about two weeks after an accident that caused the bike to fall on the right side. I changed the MC just to be on the safe side.

jayel · Posted: March 2, 2009, 2:02 pm Post subject: Re: Checking for bent forks

forks are pretty tough, if you didn't bend the handle bars you probably didn't bend the forks.... if the bars are out of line find a tree or telephone pole and bump the side of the front wheel against it to straighten them out, or block up the front end loosen all the pinch bolts and straighten them that way

snapcasezx3 · Posted: March 2, 2009, 2:46 pm Post subject: Re: Checking for bent forks

Everything is good at low speeds (I've ridden it up to about 35mph) I just want to make sure before I go 60 that everything is correct. Thanks for all the great feedback I will check it out after work tonight.

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