Butted and double butted

[Alan Farroll]

Hi,

When I look at mountain bike specs they talk about straight aluminum (alloy) frames and ones that are butted and ones that are double butted. What does all this mean? Which one is the best?

Thanks in advance

A Farroll

 

[HovR]

A straight gauge frame means that the wall thickness of the frame tubes is consistent through-out.

A butted frame means that the wall thickness of the tube is thinner in the centre of the tube, where less strength is needed. The wall thickness at the ends of the tubes will be slightly thicker for welding and to reduce flex in the frame. This means that the bike can be lightweight, yet stiff.

Double butted is just taking a butted tube to the extreme, and making it thinner still in the centre of the tube, where less strength is needed. Double butted tubes will be the most expensive, with a straight gauge frame being the cheapest but heaviest.

 

[Alan Farroll]

A straight gauge frame means that the wall thickness of the frame tubes is consistent through-out.

A butted frame means that the wall thickness of the tube is thinner in the centre of the tube, where less strength is needed. The wall thickness at the ends of the tubes will be slightly thicker for welding and to reduce flex in the frame. This means that the bike can be lightweight, yet stiff.

Double butted is just taking a butted tube to the extreme, and making it thinner still in the centre of the tube, where less strength is needed. Double butted tubes will be the most expensive, with a straight gauge frame being the cheapest but heaviest.

Hi HovR, Thanks again as this is something else I have learned. So for decent mountain biking I want maybe double butted as it will have a lighter weight. But I think I should also make sure the bike brand has a lifetime warranty on the frame.

Regards

A Farroll

 

[GrumpyGregry]

Hi HovR, Thanks again as this is something else I have learned. So for decent mountain biking I want maybe double butted as it will have a lighter weight. But I think I should also make sure the bike brand has a lifetime warranty on the frame.

Regards

A Farroll

If only it were that simple. In theory a double butted frame will be better than a single butted or plain gauge one. In reality I doubt any non-professional rider could tell much of a difference. The tyres, bars, wheels and saddle/seatpost probably make more difference to how two bikes with otherwise identical geometry feel than the butting or lack thereof on the tubes.

Sure, butted tubed frames may be lighter, thus keeping weight-weenies happy, but the rider's own bodyweight is a more critical factor and all the weight-weenie mtb-ers I know, and ride with, could do with losing a few kilo's off themselves, (as could I) not grammes off their bikes.