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pulsing when front brakes applied

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pulsing when front brakes applied

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Old 04-25-14, 04:28 PM
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zkcmurphy
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pulsing when front brakes applied

Hi people,

I'm getting into biking these days and have acquired a Kona Lanai Mountain bike from my cousin. It is a year old. When I apply the front brakes, the bike shutters/pulses. most noticeable at higher speeds, especially going downhill (road, not trail). I've examined the front wheel to see if it is warped (not true). It looks good. the bike has disc brakes and front suspension.

Any ideas? I wanted to try fixing the problem myself before going to a bike store/shop.
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Old 04-25-14, 04:33 PM
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jimc101
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Check the (a)headset, is this correctly adjusted, as if not, it could product the situation being described.
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Old 04-25-14, 05:26 PM
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zkcmurphy
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I will check that out. I youtube'd how to service the headset. Seems simple; we will see.
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Old 04-25-14, 07:02 PM
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It could be a dozen different things, from a warped rotor to play in the fork stanchions. Instead of fiddling with the headset or doing something silly like putting lube on the rotor, bring it to a shop you trust for a diagnosis. It should be as simple as a tech taking it for a spin for them to tell you what the issue is. As long as it's not too busy, they may be able to do it on the spot.
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Using a nicer sealed bearing headset vs a $10 set is like throwing a frisbee vs a dodgeball.
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Old 04-26-14, 09:04 AM
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It could be as simple as fork flex. It's going to be more noticeable with standard QR dropouts, like on your fork, when combined with disc brakes. This wasn't an issue for QR dropouts when bikes came with v-brakes, but the added power of a disc added to the lower leg is going to make flex in that area much more noticeable, especially in the high speed conditions you describe. If you're a heavier rider, it's even more noticeable. I tried to ride a rigid QR fork a few years ago and gave it up because of the excessive flex.
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Old 04-26-14, 10:53 AM
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Sounds like a cracked rim to me.
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