the 'there's no such thing as a stupid question' bike maintenance thread

Happened to me on a 3 week old set of Zonda's that i bought in CSS. Brought wheel back and first guy said "pothole" to which I said No and offered to bring him to exact spot on N81 where it happened and showed him the spot on Strava coming back doing about 12kph as i had to fully open brakes for clearance on the resulting buckle.

They replaced and trued the wheel FOC.

I was reading Eben Weiss' The Ultimate Bicycle Owner's Manual, and he mentions the correct manner to replace worn tyres, which he compares to feeding a horse (or something like that): input at the front, dejecta at the rear. So, basically, when your rear tyre is worn and needs to be changed, put a new tyre on the front and the old front tyre at the rear, and keep going. This makes a lot of sense, if you ride fast, as you always have the least likely to blow tyre at the front.

However, I wasn't sure if it actually saved you money, which is the other claim he makes; at least compared with just simply changing the tyre that's worn out and ignoring the other one until it's worn out.

I don't really know how front and rear wear rates compare (except that rear is far faster), but I decided, because I'm like that, to try a hypothetical scenario and see if it would save money, over, say, two years. In this (totally hypothetical scenario), it's more trouble and costs nearly the same. It still is safer, though whether it's worth the effort maybe depends on your riding style.

Start with two new tyres; say the rear tyre wears twice as fast as front: six months versus one year.

Just changing the worn tyre

----------------------------------------------------------------

6 months: rear totally worn, front half worn; change rear

12 months: both totally worn; change both

18 months; rear totally worn, front half worn; change rear

24 months: both totally worn; change both

-----------------------------------------------------------------

Total change: 6 tyres, changing rear tyre (the hard one) four times, front tyre twice: six changes.

"Rotating" tyres

----------------------------------------------------------------

6 months: rear totally worn, front half worn; put new on front, old front to rear

9 months: rear totally worn, front quarter worn; put new on front; old front to rear

13.5 months: rear totally worn, front .375 worn; put new on front; etc.

17.25 months: rear totally worn, front 0.3125 worn; put new on front; etc.

21.375 months: rear totally worn, front 0.34375 worn; put new on front; etc.

25.3125 months: rear totally worn, front 0.328125 worn; put new on front; etc.

---------------------------------------------------------

Total change: 6 tyres, changing rear tyre (the hard one) six times, front tyre six times: twelve changes.

If you assume the rear wears out ten times faster (say the front wear is 0.1 after six months with the rear totally worn out), you end up buying five tyres in 27.8 months.

But the other strategy leads to buying four tyres in 24 months, and a 0.4 worn-out front tyre.

So I'm not sure it saves you very much money.

Anyway, thank you for coming to my TED talk.

I bet I've made a mistake somewhere though!!