Well I assume you mean the softness of the suspension with one rider and no luggage ... as the bike was designed to be ridden?

As soon as you put another rider on and luggage the suspension becomes too soft for that weight. The suspension is not the same firmness regardless of the weight on it. Its a fixed level of resistance, designed to offer a certain level of firmness with a certain amount of weight on the bike. If you change the amount of weight on the bike, like put luggage and an extra person on it, suddenly you can push the suspension down with one finger - i.e. its NOT the same softness as it SHOULD be, because the spring is now not able to offer enough resistance for the amount of weight it is opposing - meaning it (a) now sits too low and (b) does NOT offer the designed softness of suspension - now its way too soft and can bottom out, with potentially very bad consequences.

If you change the weight load on the bike significantly, then you have to be changing the suspension to suit it. At a very basic level: a different shock will impact on how the suspension moves. A different spring will affect how high the bike sits.

That means primarily, a new stiffer rear spring to counter the extra weight. That should also make the bike sit at the same height when loaded up with luggage and extra rider, as your original spring did with just you on it. A rear spring should only cost you about 120 EUR and be fitted in an hour or so. Places like Hyperpro have a wide variety of springs for all variations of rider weights , rider+luggage, rider+passenger+luggage etc and fit them for free.

If you want to get more complicated, most suspension shops can lengthen your suspension, put in a taller spring and shock, to make the bike sit higher. But that will be a fair bit more expensive and time consuming.

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