On some SSDT and Scott Trial vids some riders are using slightly larger tanks- they appear to always be on gassers. 

Are GG the only manufacturer to offer a bigger tank for longer rides?

This tank is from gasgas contact. Other brands you have to use hebo number plate tank.

Gas Gasuk also sell a bigger tank made in the UK I think. 

Several places sell a 3.5 liter replacement tank in plastic

But only for GG? 

How come only the handlebar tank for everything else?

Because the SSDT now provides refuelling at intervals to suit the standard tanks (by and large). I remember having to buy a gallon and a half, I think, tank for my Suzuki to comply with the trial regs back in the days when petrol supply was a free for all but there was still the occasional filling station outwith the Fort.

Indeed I can recall operating the hand- operated pump at Bridge of Gaur when the Club sent a team out to run it for the day as the old wifie who ran that, alongside the local shop/post office, would never have coped.

Edited December 28, 20187 yr by 2stroke4stroke