Originally Posted by
Mimoza
26" won't run well, so we will not use 26" for sure. and our bike is made for 28", and it's absolutely great. We're now using a Specialized Pathfinder TLR Gravel Racing 700x40 instead of the Gravel Grinder 700x34, pressure is 3.4 bar, so not too much, but sufficient, the problem seems to be solved.
The strange thing about it is: We tried what
tandemdr suggested. Front weight 75 kg, back weight 65 kg, not including luggage. That's a total of just 140 kg. We carry luggage on the back rack, so we have to add a 15 kg for a longer trip. This would be almost the same weight for both wheels. Why do we get these snake bites on the back side only? No matter, we did some hundred kms without any problems, so it seems to be OK now.
Your rear admiral cannot see individual rocks that's coming so have no ways to unload the rear wheel by standing and it's impractical to do so if there are lots of rocks. You, the captain, can't possible call out 'rock' every second. When you hit rocks, snakebites will happen. 65Kg+ seated (note '+' because weight shifts are dynamic) is enough weight to cause snakebites if you don't have enough air volume. On a tandem, you basically have twice the stress there is on a single bike. When we went from 700x35/37 Continental Top Touring, which are very good tires, to 26"x2" Schwalbe Kojak, snakebites never happened again. Kojak is not a better tire than Top Touring just bigger and fatter.