How much influence do tyres (and wheels) have on geometry?

So, I changed the tyres on my 26″ bike and the BB is 1/4″ lower, meaning the head and seat angles will also be slacker.

With such a marked difference, it’s in the same league as an angleset or offset bushes.

Could wider rims and the different stance of the tyre on the rim have similar results?

So, I changed the tyres on my 26″ bike and the BB is 1/4″ lower, meaning the head and seat angles will also be slacker.

The angles will be the same unless you only put a smaller tyre on the back.

If you’ve changed both tyres and they’re similarly smaller, your angles are the same as they were before but your BB is lower. The angles would only change if you’d fitted a drastically bigger tyre at one end than the other.

You’re definitely overthinking this FWIW…

erm…… if you’ve lowered the front and rear by the exact same amount then the geometry is identical bar a lower bb

don’t forget the effect of tyre pressures.

There will be an almost imperceptible reduction in trail. Angles will be the same.

The perfect JHJ wheel you can see the conspiracy theory’s going round and around for ever.

As above, angles won’t have changed if both wheels had different tyres but trail will have changed so it will have a (negligible, IMO) effect on handling.

Makes you think, doesn’t it? 🙂

I told a little fib…

I changed the back tyre and the wheels; using the same front tyre, but on a different rim; rims are a bit wider (24mm internal over 21mm internal), back tyre is a little smaller (Highroller 2.35 instead of Kenda Nevegal 2.35)

I reckon there’s a challenging GCSE maths question in there: Using calculus, what front tyre am I using? Show your workings.

Still surprised that there is that much difference, though I do like having the lowest BB in the county.

Mason hunt eh?

front is a maxxis minion dhf 2.35.

I see what you did there, unfortunately, you’re wrong…

You wouldn’t need calculus. Trig maybe, but not calculus.

Also, calculus is more of an ALevel topic.

Calculus is a far better word than Trig, rest his soul…

Either way, you’d need a pretty extensive knowledge of knobs to work out what I’m rolling on

(There may be a clue in this post)

I hope this is on a fully rigid bike. I’d hate to think what would happen with 160mm both ends.

God dammit… Is Trigger dead too?

Afraid so…

and whatsmore:

I’d hate to think what would happen with 160mm both ends.

Afraid so~ (well 160mm on the Front, 150mm out back)

12.7″ BB