20inch To Mm

[Tripp Powell]

Icurrently have Kenda k924 20inch x 1.75 on a 18kg folding ebike (carrera cross city, see pics below). I cycle on-road and off-road in a hilly area as my main form of transport (the roads and the fields are very hilly). The fields are often wet and grassy with some well drained chalky ground with patches of smooth flinty rocks (UK south downs); it is rarely muddy. I've actually fallen off my bike once on the road (it was very rainy on a very steep hill and possibly I was only using one brake). Off-road the back tyre doesn't always grip so with the electric, the wheels often spin going up the hilliest section. Going downhill on these sections the bike sometimes slips on the wet grass.

What should I look for in a tyre to grip both off-road on hilly wet grass & smooth rocks and also on hilly wet roads? (what type of compound, BMX or MTB or hybrid, should I go with a wider width, what is the maximum width I could go, does shape make a difference)

Tire Size

You can purchase tires sized 20x1.75 with varying levels of knobby aggressiveness. If you keep your fenders you will be limited to tires with the same width as your current tires. Removing the fenders might (but only maybe) offer a little more room for a wider tire. Your frame will be the limiting factor. Wider tires do help off road.

Tire Pressure

Tire pressure does matter. This is also all about compromises. Lower tire pressure offers a better ride and better traction. If the pressure is too low you can pinch the tube and get flats on bumps. Higher pressure generally rolls better on the street. Too high will blow the tire off the rim. This takes some experimentation to find the right pressure. "The right pressure" will vary with the situation.

Tire Width

There are times when having a different width tire on the front or back makes a difference. Usually, the difference is small and in your case, if you are keeping the fenders, you don't have a choice.

Tubeless on Non-tubeless

You can put tubeless tires on non-tubeless rims by using a kit to convert your rims to tubeless compatible. Knobby tires will give you the most off road improvement in traction. I don't think you'd notice any difference going tubeless.

Selecting Your Path

Wet grass and mud are tricky. In some situations it's just plain slippery even with aggressive tires. Paying attention to your path and choosing the correct trail can be more important than the tire you have. If your path has a rut, the middle of the path often collects water and is muddy. Ride on the edge of the path, drive your tires where there will be maximum traction for the path you are on.

Conclusion

It's going to take some experimentation time and money for tires to improve your wet grass / mud traction issue and in the end you will compromise the street riding aspects of your bike.

The Schwalbe Rocket Ron is available in your 20" (406mm) size but only in a 57mm width which might be too wide for your bike. It would be pretty ideal for maximum grip on wet grass. It looks like this:

Hey I just did the same upgrade! I was going to go with the X7900 CPU upgrade I have seen people talk about here, but this CPU you suggested ended up being faster, cheaper and my iMac is still working great! thanks

Came across your post in 2016, wonder what OS you were using after cpu upgrading ? How is your iMac doing ? I would like to upgrade my iMac 2008 20 inch, have done RAM, SSD upgrading, running EI Capitan, now looking into CPU and OS upgrade. Thanks

My apologies David444. I did not see your comment until now. I run El Capitan, but I couldn't further upgrade it. It works great I have it connected to high speed ethernet, and use it almost everyday in my workshop. It continues to do everything I need it to do.

I upgraded the hard drive on mine to a 250G Crucial SSD. Then installed Mojave from a 16G USB key with a patch tool from Dosdude 1. It works perfectly even with the old 2.4Ghz Original Cpu and 4Gigs of Ram. Warning though. Do Not upgrade to Catalina, I tried it, and it &&^&* your computer speed. Cheers.

Very glad to know you could install Mojave without upgrading old CPU, would like to know if Airdrop can be supported from Mojave? I have a early 2008 iMac, 20inch, running EI Capitan, no Airdrop support. Thanks

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