I have a Trek Fuel EX8 mountain bike which I inherited from my son. It has 29″ wheels and 120 mm of suspension travel at each end. The picture above is from early this year when I was last using it. It’s a 2014 model which was a time of transition in mountain bike design. In 2014 26″ wheels were vanishing to be replaced by the choice between 27.5″ or 29″ but this was before the mantra of “longer, lower, slacker” really gained traction. Slacker refers to the steering head angle which, for early mountain bikes, had tended to follow on from road bike design at 71 degrees. Designers had realised that by making the angle less steep the bike would gain straight line stability and this change was welcomed but it pushed the front wheel forwards. This would change the balance of weight distribution on the front and rear wheels so to get the balance back the rear wheel had to be pushed backwards, leading to longer bikes. Lower refers to the height of the bottom bracket, where the pedals attach to the frame, and a lower height again aids stability and the feeling of connection with the ground.
The Trek is rather an in between kind of bike, being from the begginning of these changes in geometry. The bottom bracket height is 345 mm whereas a modern bike is likely to be closer to 330 mm even though the longer travel suspension of contemporary bikes lowers the bike even further on compression of the springs. Early in the year the Trek’s transmission had worn out leading to the chain slipping on the sprockets. The only solution was to buy a new chainring, cassette and chain which I’ve now done. I’ve removed the front mech. to use only one chainring instead of three and fitted an 11-46 tooth cassette rather than the original 11-36. This may have reduced the overall range of gears available but it’s certainly the way mountain bikes are going and gives a sufficient range for all but the most extreme climbing. I accept that I may also not have a high enough gear for road downhills but that is not important since I try to spend as much time off road as possible. With everything in place it was time to ride.
I chose to ride to Healey Nab, our local hill, with it’s man made trails because it has a good variety of conditions including some steep climbs. What I wasn’t noticing was the feeling of being high above the ground which I’ve noticed previously. I think this may be because I’ve removed an unreliable dropper seat post and fixed the saddle in a fairly low compromise position. I certainly noticed a smooth ride over bumps given by the larger wheels. A large diameter wheel hits a bump early so by the time the axle is at the top of the bump there has been a slightly longer period of time. This means the wheel rises less sharply and so it feels smoother. I believe that 29″ wheels are superior to the smaller sizes. The 120 mm of suspension travel is less than the 140/130 mm of my Boardman but I still think I found the ride over one particularly tricky section of trail to be a little bit better. This is a challenging piece of ground at speed because it has repeated bumps. If your wheel hits the first bump and it isn’t fully absorbed by the suspension it will take off to smack into a following bump. This year I’ve been practicing getting my body low to the bike with flexed arms and legs. This way I can absorb the bump then extend to push the bike into the dip, thus keeping the wheels in contact.
My first run wasn’t perfect but by really concentrating on my technique I got it right later and felt that, despite the shorter travel suspension, the 29er was possibly slightly better than the 27.5″ Boardman which I’ve been riding recently. Despite muddy conditions I had a good ride and 3 laps gave me a valuable workout. I think I’m going to enjoy riding the Trek this winter.
Mountainbiker 