What makes this noise?

I have heard this sound in a handful of different DH racing videos, and always wondered what exactly causes it. 

I found a Pinkbike video that is a great example, the very first clip. Ronan sends a huge gap and seems to bottom out, and the bike makes a fart noise. It definitely sounds like the tire is rubbing on something, im just not sure what. If i had to guess, perhaps the back of his seat? Is it common for DH bikes to be able to compress enough for the tire to rub on the seat like that? Or is it something else causing that noise? 

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chadkriz
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7/25/2016
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Santa Cruz, CA US
4/10/2026 9:57pm

just the tire hitting seat.

Wouldn't that send them OTB? Whenever a rider gets their arse caught up in the tire it severely pitches them forward.

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1
4/10/2026 10:23pm

just the tire hitting seat.

chadkriz wrote:

Wouldn't that send them OTB? Whenever a rider gets their arse caught up in the tire it severely pitches them forward.

no its like hitting the rear brake.....

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dolface
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4/11/2026 1:33pm

just the tire hitting seat.

chadkriz wrote:

Wouldn't that send them OTB? Whenever a rider gets their arse caught up in the tire it severely pitches them forward.

That's 'cause the rider gets shoved forward by the tire, the saddle doesn't move...

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AgrAde
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AL US
4/11/2026 4:30pm

I used to run my Tues with a bit of tire/seat interference. It made noise but it wasn't like jamming the brakes on at all. I expect it depends heavily on the seat and how much interference there is but they're not gonna set their bike up so it fucks up their run if they use too much travel...

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dolface
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CA US
4/11/2026 4:38pm
AgrAde wrote:
I used to run my Tues with a bit of tire/seat interference. It made noise but it wasn't like jamming the brakes on at all. I...

I used to run my Tues with a bit of tire/seat interference. It made noise but it wasn't like jamming the brakes on at all. I expect it depends heavily on the seat and how much interference there is but they're not gonna set their bike up so it fucks up their run if they use too much travel...

Some DH specific saddles also have a notch in the tail to give more tire clearance...

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AgrAde
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AL US
4/11/2026 5:01pm

Yeah, like my Tues seat.

I came from trials and bmx so I was used to having the seat near my ankles haha

3
Ob917
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Location
Cardiff, CA US
4/11/2026 6:39pm

Mine makes a noise like that sometimes. It’s my front numberplate when I use all the travel up front. 

2
4/15/2026 4:00pm

just the tire hitting seat.

dang so it really is that huh? 

So in addition to bottoming out the shock, the frame is also flexing a few mm up to the seat? Damn thats some serious impact.  

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