Tyre installation and testing.

My winter bike, the Trek Fuel EX8, has 29″ wheels. It was fitted with a very grippy Maxxis Minion DHF tyre at the front and a rather worn Maxxis High roller II at the rear. The effect of this was that I found the rear wheel starting to slide before the front most of the time. I tried moving my body weight backwards and putting less pressure down onto the handlebars and this does improve rear wheel grip at the expense of front but the bike was still unbalanced. I inherited the bike from my son because he no longer used it but I hadn’t looked at the spare tyres which came with it. One was a Minion DHR to match the front so yesterday I swapped it with the High roller.

Changing tyres was easy in the past but now, although I still use inner tubes, tyres are designed to be tubeless capable. This means that the beads around the inside of the tyre needs to be much tighter to keep the air in so they can now be difficult to fit. My best advice for MTB tyre fitting is to throw away your tyre levers before you start. They may work OK for tubeless but if fitting tubes there’s a big chance that you’ll nip the inner tube and have to start again. To remove the tyre I let the air out, compressing the tyre as much as I can, then break the beads away from the rim on both sides. It’s then a question of pinching the carcass firmly between the thumbs and fingers of both hands and on the fingers side encouraging the bead to the out side of the rim. As soon as you get a small section over it becomes easier then you can get the tube out and pull at the tyre to remove it completely.

Fitting is even harder, though this varies from one type of tyre to another. I first checked the arrow which shows which way the tyre should rotate and pulled it onto the first part of the rim. I then used my thumbs to massage the bead over the rim all the way around until I had just a short section left which needed extra force. With one side on I then tugged the carcass across to where it needs to sit, as close to the rim as possible. This gave room for the tube, which needs a tiny bit of air in, just enough to give it shape. I then started to push the second bead on with my thumbs. Towards the last part I also tried flipping the wheel around, putting my thumbs on the opposite rim and using the fingers of both hands to pull the bead over. With determination I had it on and there was no chance that I could have knicked the tube. Today it was time to test it.

In the picture the High roller on the left has closer spaced side knobs than the Minion DHR on the right. This means that the Minion has a better chance of pushing the knobs through the mud to a grippier surface below. The central knobs are also more aggressive to improve traction and braking.

The Minion DHF is wider at 2.5″ compared to 2.3″. This is a counterintuitive idea and tends to be the opposite to what you’d see on a motorcycle. The reason for a narrower rear tyre is so that it doesn’t float across the mud as easily but instead digs in to find grip. The central knobs are more longitudinal than transverse on the front tyre to aid steering at the expense of traction.

I took the bike to the site of my last ride at Birkacre. I’d be able to directly compare the rear tyres in very similar conditions. Firstly I used a section of 3 downhill corners which flow into each other and rode round 3 times. The balance between front and rear was now about perfect. I could adjust the pressure on the handlebars to get both ends breaking away together, the nirvana of cornering on the dirt. I then rode a circuit in exactly 8 minutes which is all natural trails, rather than being built for mountain bikes. There are multiple chances to slide and yes, I did lose grip a few times, but was always in control. I noticed how the better grip at the back increased my cornering confidence. Perhaps surprisingly I noticed how the new rear tyre helped to improve the steering. This is because with better grip and far less small skips to one side or the other the bike was staying pointed where I wanted it and I wasn’t constantly correcting the direction. Braking performance was much better in the muddier parts.

I rode around a little more then worked hard up the long gravel and mud climb to Eaves Green on the way home. The change of tyre has been a big improvement in confidence and the balance of the bike on corners.

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