There are many mountain bike brands on the market. Mountain Bike designers and makers from around the World, create an infinite range made up of different frame sizes, wheel sizes, colours, and components. Anyone can visit bicycle stores online and in person at bricks and mortar bike shops to see just some of the models that are available.

Each manufacturer produces a model that is made up or assembled from a component buffet or a bike part smorgasbord of suspension options, wheel types and gearing. Norco did a brilliant job of creating the aluminium frames of the Storm mountain bike range but on two models that we tested, the gearing is seriously flawed.

The first mountain bike actually purchased for this test was a large frame 29 inch wheel size Storm 4.

When tested, the ride experience was as expected. It was a competent and functional mountain bike that did its job except in high gears.

In high gears, the chain slipped and jumped as the chain ran off the rear small gear in the sprocket cassette under load. A slipping chain can be dangerous when the rider is pushing hard uphill or when making a sharp turn.

The dealer offered to adjust the drive train but the chain slipping was not something that could be eliminated by an adjustment. The bike was brand new and a chain should not slip. That sort of event usually happens when a mountain bike has been used for a long time and the chain has stretched or the gear teeth have worn.

I took the bike back and exchanged it for a more expensive version in the hope that it would be better. I paid over a hundred and thirty Australian Dollars more for a Storm 3.

The Storm 3 extra large 29" mountain bike is brilliant. The ride position and the gear ratios are perfect. On the road, it is like flying a glider along the ground. Being so light, the bike is easy to get up to speed and highly agile around corners during ascent and descent. If it wasn't for the gears, it would be stunning value.

Once again, just like in the Storm 4, on the Storm 3, when using the highest gear, the chain slips and spontaneously tries to change into the same gear. Again, it is dangerous to ride this bike in an aggressive way. A mountain bike with a problem that causes chain slipping and jumping is never good and what's worse, is that slipping does not only happen during hill climbs. Under load in top gear during a hill climb, the chain slips on almost every push of the pedal. Similarly, on flat ground, when riding over bumps, the chain will slip.

Sadly, the high gear is ideal for me as a rider. It is my gear of choice for mild uphill work and cruising along tracks.

The good news is that I found a fix.

The bad news is that I had to turn the bike into a one gear version to be able to use it safely.

I stopped gear slipping completely by tying up a part of the derailleur. The effect of the modification is that more teeth on the sprocket are engaged with the chain and the chain approaches the sprocket horizontally, not at around 90 degrees.

I love this bike. It is almost perfect. The problem is that it has a gear system design fault that makes it irritating to ride most of the time and dangerous to ride in extreme conditions.

I won't take the bike back or hunt for something better for the price or even more money, because as a one gear mountain bike it is perfect on trails and tracks. One benefit of having the high gear only is that the extra effort required to move this bike along will certainly tone up all of the muscles that push the pedals.

Update 28 June 2020

The Norco was taken back to 99 Bikes in Australia for the free service.

The person in charge of servicing bikes at the outlet that I purchased the Norco from, advised that they had "reports" and "incidences" of the chain slipping and that the fix was to replace the cassette with a better quality product.

The dealer installed a new Shimano during the service. There was no charge to me.

I tested the bike over 10 km of track and roads and there was no slipping.

I can now use all of the gears and there is no need to strap up the derailleur.

If you buy one of these bikes, raise the derailleur issue and ask for a better cassette before leaving the store.

More https://www.norco.com/bikes/2019/mountain/cross-country/storm-aluminum/storm-3/