You have the right to by an item that is free of defects and fit for purpose. If it is not then the manufacturer or distributor has to fix it at no cost to you. This is specified here in Audtralian consumer laws.
If it was before 2011 then this applies.
Consumer guarantees from 1 January 2011Currently, consumer rights are covered under the Australian Consumer Law The following implied warranties and conditions apply to products and services purchased prior to 1 January 2011.
Products bought prior to 1 January 2011Products must:
[ul][li]be of merchantable quality, which means free of obvious defects and meet basic levels of quality and performance for their price and description[/li][li]be fit for purpose, which means do everything usually expected and as you described to the salesperson[/li][li]match the description you were given or the sample you chose from[/li][li]have clear title, including products bought at auction. That means the salesperson must tell you of any restrictions on ownership before you buy the product[/li][li]have quiet possession, which means the salesperson must tell you of any debts, charges or restrictions on your ownership before you buy.
After 1st January2011 this is the new laws.
Consumer guarantees on products and services Since 1 January 2011, the following consumer guarantees on products and services apply.
Products must be of acceptable quality, that is:[ul][li]safe, lasting, with no faults[/li][li]look acceptable[/li][li]do all the things someone would normally expect them to do.[/li][/ul]Acceptable quality takes into account what would normally be expected for the type of product and cost.
Products must also:
[ul][li]match descriptions made by the salesperson, on packaging and labels, and in promotions or advertising[/li][li]match any demonstration model or sample you asked for[/li][li]be fit for the purpose the business told you it would be fit for and for any purpose that you made known to the business before purchasing[/li][li]come with full title and ownership[/li][li]not carry any hidden debts or extra charges[/li][li]come with undisturbed possession, so no one has a right to take the goods away or prevent you from using them[/li][li]meet any extra promises made about performance, condition and quality, such as life time guarantees and money back offers[/li][li]have spare parts and repair facilities available for a reasonable time after purchase unless you were told otherwise.[/li][/ul][/li][/ul]
I have bolded the sections that are relevant to the models but if more than one or two people complain and even better if a class action is used of say ten or more people at once on one complaint etc, you might get them to supply the new wheelsets and gears for free like they are obliged to do. It wont be cheap for them but it would be cheaper for them to just do it rather than face a huge fine, remedying the problem gratis and possible have trading restrictions placed on them or else being closed down entirely. The goods are faulty from the factory so it is the Australian distributor/manufacturer who has to make them right!