My first post on this forum was about my new cyclo cross bike and i have to admit that i still cannot get enough of it. Everything is better than i hoped for except for the disc brakes and wheels. I will discuss the wheels here. My requirements for a CX bike’s wheels are the following: · I ride mostly road and the traffic forces me to do a bit of off-roading every now and then. Large knobs for riding in mud like the Europeans are therefore not necessary · The UCI regulations limit tyre width to 33mm for CX. Pointless for the majority of owners of these bikes as it may work on grassy and muddy courses in Holland but you cannot ride over rocks at speed and I think a minimum of 35mm is required. · It must be tubeless. Non-negotiable. You cannot ride through the thorns we have everywhere in the Cape with inner tubes and you will also constantly be fixing pinch flats. RIMS I chose Stan’s Grail X which hooks up perfectly with tubeless tyres but they are simply too soft. I put 8 dents in them in the first 8 weeks. Alternatives would be a ‘ghetto tubeless conversion’ [you just build up the rim bed with a few layers of rim tape] but I have no experience with this. Another option would be to simply use 29er MTB rims [they are also ‘700c’ or 622 sized] but are quite a bit wider and I’m not sure how the tyres will sit on them. TYRES The bike came with Vittoria Xg pro 700x31c tyres and they are made for mud [very knobbly] and WAY too narrow [hence the 8 dents in my rear rim by the time my replacement tyres arrived] Next up I had a Challenge Gravel Grinder 700x38c on the back. Very nice tyre but although it is 38mm wide, it is not very high and you end up with too little volume to run it softer on poor terrain. Furthermore it’s not tubeless specific and climbs off the rim at higher pressures [more of this below]. The file thread did not last very long. I thought the answers to my prayers would be Continental Cyclocross Speed 700x35c. Perfect thread that should last much longer than the others and for the road, conti makes the only tyres I ever trusted to trained with. Also very light at 350gm. The first time I mounted them was fine but I took them off to try something else and a month later when I remounted them, my troubles started: · When I inflated them to anything over 45 PSI they would come of the rim. This happens suddenly. With no warning. And very loudly. I don’t like it. · They oozed Stan’s fluid through the sidewalls ???! this continued for 2 weeks and I have now put an inner tube in them. see picture So although they are brilliant tyres, I now have two of them that I will try to run with tubes through the winter when we have less thorns but will not buy them again The tyre I was least excited about was WTB cross Boss 700x35c. [heavy, large knobs so noisy and does not roll well on the road] . Man, was I wrong about them. Hooking them up tubeless is a non-issue. No punctures. Although they are 35 wide, they are about 38mm high and this volume makes it easy to run them at pressures down to 27PSI off road. If the thread design was closer to the Contis’, I would stop my search for sure TUBELESS Setting a T/L specific tyre and rim combo up is extremely easy. The problem is the paucity of options when it comes to my T/L tyre requirements and invariably you will use non-T/L tyre. They usually work well except that you have a very limited range of pressures you can run them at. Tyre pressure is much more of an issue on a CX bike than any other type. So if you ride off road, you want them around 30 PSI and on the road as high as you can. The indicated pressures on the side walls are completely irrelevant. The most revealing bit of info has been the very fine print on the Stan’s rim: depending on the tyre width, the max pressure for a 23mm tyre is 116, for a 28mm it is 100 and for 32mm it is only 45 PSI ! If you inflate a [especially a non T/L ] tyre to 46 PSI, it will come off. Suddenly. Loudly. You put a tube in it and you can go much higher – this is something I find mildly puzzling but it’s a fact. So as with most things, engineering is the art of balancing compromises and no set up will by flawless. I will settle for the WTB Cross Boss and may even try their 40mm Nano [weighs a tonne though] on the rear. When it’s time to replace my rims, I would hopefully have more options as tubeless disk rims should expand a lot in the next few years.
