[Bikester]

So currently I am running a shimano 105 and I was wondering what exactly makes the ultegra better?

[bob dopolina]

Mostly weight.

This is achieved through using different grade materials such as alloy bolts instead of steel.

I think the biggest difference would be in the chains and cassettes in terms of wear. There might be a slight improvement with performance but only when you took the group nearer to it's limits.

105 is a solid, workhorse group.