Jakarta pump track: Steeper berms?

Hi Lee, hope all is well… this is the little park that me and my partner designed in Jakarta-Indonesia. I have build the pump track following the guide from your book. Please have a look and tell me what you think of it? I’m planning to build another one on my friend’s backyard. Do you think the berms are not steep enough? I’ve always loose my front end on them as I get faster…. Thanks in advance

Hey Andre,

Thanks for writing.

First:

Wow, beautiful work.

I love how precise everything is. And that clay — it looks like you can shape it however you want (but I’ll bet it’s slippery when wet, sticky when damp and cracked when dry). Oh well, at least it’s easy to shape.

Second:

I know this bank is 70 degrees (I measured), so I can rail it with full confidence. The Giant Pump Track at Keystone, CO.

Yes, make the berms steeper. Always make them as steep as you can.

A good rider on a well-built pump track can pull 3 Gs in the turns. That correlates to a 70-degree lean angle. If your banking is at least 70 degrees, you can make that turn without needing any traction at all. It’s the same math used to design roller coasters; no matter how fast the car is cornering, it’s always pressing straight into the track.

With that clay, you can make your berms vertical (or even over vertical — yes, do it!). With vertical berms, you can theoretically corner infinitely fast.

Third:

When the Gs build up in a sweet corner, you’ll instinctively push your weight back to save your brain from danger. That unweights the front end and invites it to drift.

Don’t do that!

Balance right over the middle of your bike. Heavy feet, light hands!

Fourth:

Braaap!!!

— Lee

Know more. Have more fun!

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