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The Starting Line : What is meant by top bulb racing vs. bottom bulb racing?

Motorcycle Drag racing Sportsman

The Starting Line is a biweekly column for our Sportsman drag racers brought to you by Schnitz Racing. Every other week we will feature a frequently asked question and have it answered by a panel of experienced sportsman racers, led by Ben Knight. Having questions answered by multiple racers will give our new racers several perspectives on the information they want. If you have a sportsman related question, submit it to editor@dragbike.com.

What is meant by top bulb racing vs. bottom bulb racing?

Jerry Turner

A top bulb racer would use a delay box. A bottom bulb racer would not be using a delay box. A delay box allows a racer to release a button on the first bulb as the tree comes down and the timers in the box take over and release the bike (theoretically) as the green light is coming on. The advantage of a delay box is eliminating the distraction of the tree coming down and eliminating the possibility of anticipating the third bulb and going red. Some delay boxes can also be used to cross over or use your slower opponent’s top bulb eliminating any distraction from his side of the tree. Depending on the organization and/or track, a delay box may or may not be allowed for the motorcycle class. Check with the track operator or the racing organizations rule book to find out if boxes are allowed.

Dustin Lee

Top bulb racing is delay box racing which is the use of a timer and your enter a time to make it where the rider can let off a button on the top yellow and the bike leaves the line once timer runs out… Bottom bulb racing is that exactly all rider leaving on the bottom yellow at the perfect time to get a great reaction time!

-Be safe

Dustin Lee

If you use a delay box, you will have some kind of button to either release your air clutch or two step. When the top yellow light comes on, you release your button. The delay box will then hold the bike by the delay time that you entered in the delay box before it allows the bike to go. That is top bulb racing. Delay boxes are not legal in NHRA Div 1 motorcycle classes and MIROCK.

Bottom bulb racing is when you leave on the bottom yellow bulb without the aid of any electronic devices. You are allowed in most sanctions to have some kind of Mechanical delay device (ie long button, adjustable air bleeder on air clutch, etc). Why would I need to delay on button bulb racing you ask? Well some bikes can really move to quick off the line to leave the second the last bulb lights, so it’s easier and more consistent to use some kind of Mechanical delay than delay in your mind. There are a lot of ways to delay it electronically on the bottom bulb, but it is flat out cheating and shame on you if your doing that.

My choice of slowing myself down if I’m going red a lot or to close to red, is adjusting my clutch lever and where I hold it from where the clutch engages. I only have a hand clutch with no wheelie bar, and I don’t leave on a button or a two step, so this works for me. It’s not as consistent, but it can work effectively. I also find it more consistent to focus on the bottom bulb and not follow the lights down. I block the top two bulbs once everyone is staged by lowering my helmet and squinting my eyes. If you race me, just leave on second bulb.

Janie Palm

Reacting to the top bulb of the tree, “Top Bulb” also referred to as box racing or using electronics to cross over (see answer to “What is Cross Talk?”). Bottom bulb is referred to as reacting to the bottom bulb of the tree normally non-box racers use the bottom bulb.

Brad Gott

Top bulb and Bottom bulb racing. Hmmmm you got me on that one. I’m not sure, but I believe it has to due with delay box racing.

We’ll see you in two weeks for another addition of the Starting Line, in the meantime check out our column sponsor Schnitz Racing.


Volume 1 – Issue 1 : What is the best advice for someone going down the track for the very first time?

Volume 1 – Issue 2 : How do I decide what class to enter? Most tracks have a street class and pro bike class but I sometimes see streetbikes racing in the pro bike class with the bar bikes.

Volume 1 – Issue 3 : What is the difference between a bracket class and an index class?

Volume 1 – Issue 4 : What is the difference between a pro tree and sportsman tree? And what is the best technique for cutting a light?

Volume 1 – Issue 5 : What is rollout and how does it affect my ET??

Volume 1 – Issue 6 : Does a practice tree really help with your reaction time and do you have any tips to how to use it?

Volume 1 – Issue 7 : What is courtesy staging?

Volume 1 – Issue 8 : What does “the race was won on the starting line” mean?

Volume 1 – Issue 9 : How are bye runs determined? If I get the bye, should I make the pass?

Volume 1 – Issue 10 : What is the best technique for a burn out?

Volume 1 – Issue 11 : What is cross over / cross talk?

Volume 1 – Issue 12 : Some racers do a quick launch after the burnout, why is that?

Volume 1 – Issue 13 : Do you have any advice on methods for consistency?

Volume 1 – Issue 14 : Do you recommend changing visors for daytime and night racing?

Volume 1 – Issue 15 : Deep Staging verse Shallow Staging

Volume 1 – Issue 16 : Some people log all of their runs and are always looking at old timeslips. How does this help them?

Volume 1 – Issue 17 : What do all the blocks on the track represent and how should I use them when racing?

Volume 1 – Issue 18 : What does sandbagging mean and should I try it?

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