I see that Malvern don't highlight rider height and weight on their website info (https://www.bicyclesuperstore.com.au/malvern-star-sprint-1-2019.html) for this bike, but they do highlight that it's a lightweight alloy framed bike. I'd suspect that at 100kg you may be at or above the intended weight for the bike (I know my road bike has a 95kg rider weight limit on a steel frame and I've broken spokes when over 100Kg).

Close to the limit of the bike's weight riding style will affect if you damage it or not... riding 'light' - using your ankles / knees / arms to soften your impact on bumps - or riding 'heavy' by just sitting on the saddle can alter how well the bike carries a rider around it's limit.

The geometry of the bike (Malvern describe the riding position as upright) means more of the impact is carried by the back wheel than if you were less upright. And because of the odd dishing of the back wheel (to make room for the rear block) the spokes are quite heavily stressed already.

It would be worth talking to the bike shop about the weight limit - if they sold you a bike that has a rider weight limit of 90Kg then maybe it was mis-sold. If it was mis-sold perhaps they would fix it for free or maybe they'd replace it with one more suited to you. I've been down this route you are starting on... I used a heavy (steel framed) mountain bike initially until I'd lost enough weight to ride the lighter faster bike. The mountain bike feels agricultural but it survives all I've thrown at it over really bad roads.

I see that Malvern don't highlight rider height and weight on their website info (https://www.bicyclesuperstore.com.au/malvern-star-sprint-1-2019.html) for this bike, but they do highlight that it's a lightweight alloy framed bike. I'd suspect that at 100kg you may be at or above the intended weight for the bike (I know my road bike has a 95kg rider weight limit on a steel frame and I've broken spokes when over 100kg).

Close to the limit of the bike's weight riding style will affect whether you damage it or not... riding 'light' - using your ankles / knees / arms to soften your impact on bumps - or riding 'heavy' by just sitting on the saddle can alter how well the bike carries a rider around its limit.

The geometry of the bike (Malvern describe the riding position as upright) means more of the impact is carried by the back wheel than if you were less upright. And because of the odd dishing of the back wheel (to make room for the rear block) the spokes are quite heavily stressed already.

It would be worth talking to the bike shop about the weight limit - if they sold you a bike that has a rider weight limit of 90kg then maybe it was mis-sold. If it was mis-sold, perhaps they would fix it for free or maybe they'd replace it with one more suited to you. I've been down this route you are starting on... I used a heavy (steel framed) mountain bike initially until I'd lost enough weight to ride the lighter faster bike. The mountain bike feels agricultural but it survives all I've thrown at it over really bad roads.