Modifying Your Bike – Within the Rules

Vintage trials tend to attract people who enjoy riding old, out of date & thoroughly not modern bikes – while still having great fun. Sure, modern trials bikes work better, but it’s amazing how good a rider can do on old iron. You know – really “old school”.

Classes for vintage trials events run from hard-tail pre-unit (pre 1950’s models with no rear suspension and separate transmission & engine) to modern twin-shock bikes. The question for a vintage enthusiast is how much can you do to your bike and keep within the rules. (MWVTA Rules). Any modifications should always be done in the spirit of the class you are entering.

Let’s talk about the most popular class for “Historic” bikes made from 1973 to 1979. These bikes work very well and are commonly used in modern trials events in head to head competition with good results against modern bikes. Modern tires, shocks, and electronic ignition can be used, while tubeless tire rims, power valves, boost cans or modern power boosters are not allowed. Wheels, front ends, motor parts, etc., from other bikes- even different brands- are OK as long as the “donor” bike was manufactured in 1979 or earlier. Some allowance is made for a model that was continued to be manufactured through latter years as long as the particular part being used is the same as it would have been on a ’79 or earlier model.

Next we have the modern twin-shock class, which are bikes made from 1980 to the present. In this class almost anything goes, just make sure it’s air cooled, cable clutch (no hydraulics), drum brake, twin-shock bike is allowed to compete. Even modern trials bikes with conversions to drum brakes and twin-shocks are seen competing in this class.

There are other classes to ride in as well – for bikes manufactured all the way to the present day modern trials bike. While the vintage trials community focuses on vintage events with vintage style sections  – the ultimate goal is to promote trials in general, along with the camaraderie, friendly competition and family friendly sport that observed trials is.

Modifying your bike is a big part of vintage trials – just make sure that your modifications will allow you to compete in your chosen class. And if you find the modifications you made disqualify your bike for a particular class – there is sure to be another class you can compete in.

Remember, rocks are our friends.

by John Clement & Chuck Moline



Edit Mar 31, 2013 – The reference to “round slide carbs” was removed pending further research. We’ll plan a later article for you solely about carbs.

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