mrs_oab’s new to her Giant Invite has room in the rear for 38mm tyre and mud guard.
The front however is over 55mm wide at the fork brace…

Being used to MTB only, I’m wondering about going for 45mm+ in the front, with full guard. Slacker angles, more cushioning, confidence…

The bike will mainly be used on rural roads and forest tracks.

Thoughts and pictures if you already have one.

I’m forever mixing and matching tyre sizes on my Voodoo…

Since Sunday, it’s been 700*38 Gravdal up front and 700*28 4Season on rear.

For a few weeks beforehand, it was 700*50 Century.

Before that it was Century up front and 26*4 Jumbo Jim rear.

IIRC the headtube angle is 69.5 degrees in default fattie mode. Default stem was 80mm +6 degrees, currently 110mm -8 degrees. Default bars 720mm, Knuckleball 747mm. 90%+ on the road.

I’ve realised that @epicyclo has probably done this since 1982…

matt_outandabout
I’ve realised that @epicyclo has probably done this since 1982…

1982? That’s only yesterday. 🙂

I’ve been fitting the fattest tyres possible into my bikes since I was a kid in the African bush in the 1950s.

Probably the most useful bit of advice I got in my cycling life was from the fundi in the duka where I bought my freedom machine (a rickety ancient roadster) – If you’re not going to stick to the hardpacked tracks, fit the widest tyres possible.

That was about 1.75″ if I remember right, so 45+mm seems perfect.

Fat tyres open up the world.

Chubbier without affecting angles would be to go down a wheel size too.

FWIW I remain to be convinced that slacker always equals better.

scotroutes
FWIW I remain to be convinced that slacker always equals better.

Me too.

I think the benefits are largely so that telescopic forks don’t bind (around 64º seems to be the best compromise), and also that for a given toptube length it places the front wheel further from the CoG. Floppy shite if you like to ride up steep hills though, but maybe that explains the fashion for really wide bars.

It would be an interesting experiment to build a bike with the same wheelbase but a steeper headangle and see how that rode.

But unicyclists blow all bike geometry theories out of the water. Or maybe they demonstrate that the ability to radically change the CoG position of the rider is the most important virtue of any design, and everything else is secondary. 🙂

I’ve decided to stick a 38 on the back, looking for 40-45 on the front, just for comfort. It’s currently wearing original Giant 35’s, that seem to be quite narrow for the rated size.
Mrs_oab is only one ride in. I’ve just flipped stem and changed bar angle as well as she is upper end of the frame size (first bike ever we’ve had that issue!).
I’ve lowered tyre pressure as well, and looking to go tubeless.

What’s going on with that front brake cable?

I’m not sure, trying to work out if round the inside is better.

I wouldn’t bother. Stick to 40 Max. Any bigger and the slight increase in comfort doesn’t make up for weight penalty of the bigger tyre.

trailwagger
…Any bigger and the slight increase in comfort doesn’t make up for weight penalty of the bigger tyre…

…until the bike is ridden on rural roads and forest tracks.

…until the bike is ridden on rural roads and forest tracks.

Yea, but it’s undeniable that a 2″ tyre is slower than a 40mm tyre, is slower than a 30mm tyre up until the point where you start having to chicken out and slow down.

And IME by the point you get to 2″ tyres drop bars stop making much sense except in very niche applications. You’re not doing an aero tuck, or bothered about the comfort of multiple hand positions down a trail that needs >2″ tyres.

Also, there’s little point in mismatched tyres IME. I’ve got 35mm on the rear and 40mm up front and it already feels like I’m nursing the back end through stuff the front just shrugs off.

That and (controversial opinion klaxon) big* tires aren’t all that comfortable. Hit a root with a 4″ tyre at 10psi and it barely deflects, all the shock ends up at the bars. Hit a root with a 40mm tyre at 30psi and (as long as you don’t hit the rim) it uses all 40mm to absorb the shock. You can’t drop the pressure as quickly as size increases as you quickly reach the point where the tyres squirm in the corners so bigger tyres end up harder (but much less likely to pinch flat).

You can run a big tyre at lower pressures, but only on soft ground where cornering loads are lower because grip is limited and don’t cause it to squirm.

*off road, a 40mm slick is still more comfy than a 23mm on road, probably for the opposite reason, the aggregate in the road surface is often ~1″, so a 40mm tyre is deforming around it, so a 1″ square impact is pushing it at ~40psi, or a 1″ tyre at 100psi, therefor more comfort. Whereas off road the surface tends to be made up obstacles > than the tyre size, so the force doesn’t decrease with tyre size (remember regardless of tyre size and pressure the average force is equal to the bike + rider weight)

…until the bike is ridden on rural roads and forest tracks.

Exactly, rural roads and forest tracks, not a black run at your local bike park. 40mm is plenty for comfort in these circumstances. Anything more is overkill, and then you get the weight/drag penalty.