Ive just bought a second hand mountain bike (specialized hardrock with disc brakes) and it is almost new, but the front wheel slows down very soon. I have noticed that when I open the quick release flap it doesn‘t slow down as quickly but when i close it it then slows down the wheel. Please help, any answers appreciated, I am new to biking and don‘t know a thing lol thanks
Typically when a wheel slows down like that, its the brakes rubbing on the rims. When you mount the wheel into the quick release, it may be crooked to the left or to the right, rubbing on the brakes. Try refitting the wheel in by letting the bike's weight to push the axle into the fork as much as possible, then tighten the quick release. If still having trouble, put the bike upside down (on a towel, or something soft to prevent scratch to handlebar) and try to fit it this way. By the way, before taking off the wheels you need to release the v-brake calipers. When you put them back on make sure you fit the brakes in correctly, give the brake a few squeezes and make sure there's a small space between the rim and the brake pads. Another problem could be the wheels are not straight. In that case get a bike shop to take a look on how serious the problem is.
the problem here is in your hub. The hub is the center of the wheel which attaches to the fork. To adjust this you will need a couple of thin flat wrenches. The size of these are 15mm, 16mm, or 17mm. What needs to be adjusted is the cone nuts on the axle. They are to tight, this is what's causing the wheel to slow down rapidly once the Quick Release skewer is closed. Remove the wheel from the bike and use the wrenches to adjust the bearing cones so they are free from side to side wobble but spin freely. Once this is completed hold the wheel and spin it. The wheel should spin smoothly and ease into slowing down, not spin for a few rotations then stop. Once completed, reinstall wheel. Hope this was helpful
The previous three answers all have good points, but you specifically stated you have disc brakes; so please ignore all the parts about the pad rubbing on the rim. First thing is to try loosening the quick release slightly (unscrew the nut on the non-lever side a little). Don't overdo this, as it clearly needs to firmly hold the wheel in place!! Also, while the quick release is released, wobble the wheel back and forth to push the brake pads away from the rotor. Try that and then, with bike upside down or in a stand, spin the wheel and listen for contact at the brake rotor. Apply the front brake a few times to 'reset' the pads, and listen again. If it's not that, it's likely the brake adjustment (cable or hydraulic?) or the hub, but I'm hoping the quick release was just too tight. If you're new to this and need to proceed further with hub or brake adjustment, it's worth picking up a book like Zinn and the Art of Mountain Bike Maintenance. Also, the Park Tools web site has a lot of 'how to' items. If you don't want to dive into this, take it to a shop, as it shouldn't be too big of a repair.
