I have 2 bikes at the moment. One Genesis Fugio and one Spesh Allez. I can spend all day comfortably on the Genesis but get fidgety/uncomfortable after an hour on the Allez. The geometry is pretty identical with the exception of head angle. So why do they feel so different?

Fugio Medium Allez 56m
Seat Tube 530 530
Top Tube 567 564
Reach 385 385
Stack 594 596
Head Tube 165 180
Head Angle 70.5 73.5
Seat Angle 73 73.25
Wheelbase 1045 996

Is it the head angle?

Pretty identical? Hardly. Head angle, fork length, chainstay length are all very different. They’re also made of different materials and I’m guessing that you have larger tyres on the Fugio?

Tyres, pressure, saddle and height, bars and setup?

Is it the head angle?

No, the reach is identical so it makes no odds.

Pretty identical? Hardly. Head angle, fork length, chainstay length are all very different. They’re also made of different materials and I’m guessing that you have larger tyres on the Fugio?

Stack and reach are identical so fork length is irrelevant. Chainstay length? don’t know why that would affect anything position wise. And materials tyres etc same. I am talking about riding position not comfort over typical terrain.

the Fugio is a long wheelbase slacker angled fat tyred gravel bike, the Allez is a shorter wheelbase tighter angled narrow tyred faster handling road bike

No, the reach is identical so it makes no odds.

🤔

So I didn’t make it very clear in the op. I am talking about seating riding postion, not how comfy the bike is or how it handles over certain terrain.

Got to say I agree with Simon. Very few of those measurements are the same. Reducing everything to bar position (stack and reach) may be simplistic when considering why a bike becomes uncomfortable on longer rides (but presumably feels fine for short ones)

Got to say I agree with Simon. Very few of those measurements are the same. Reducing everything to bar position (stack and reach) may be simplistic when considering why a bike becomes uncomfortable on longer rides (but presumably feels fine for short ones)

I think 2mm is close enough to not be noticeable don’t you? If seat angle, stack and reach are all the same (or within 2mm of each other) then why does the riding position feel so different?

Same stem length/angle and handlebar reach/width?

I’m out

I’m out

Thanks for your help.

how long are the stems on each? stem angle? bar height?
the longer wheelbase alone makes the Fugio more stable and (in my experience) less tiring to ride

Are you using the same saddle set at the same angle? If not then perhaps a slightly different pelvis angle is the issue.

Simple way of telling at least if the “cockpit” reach is the same would be to measure the distance from the center of the stem to the top of the hoods, where you rest your hands.
Handlebar drop is slightly harder to measure, but you could use a length of wood propped on the saddle and top of the bars and a phone angle measuring app.

No, the reach is identical so it makes no odds.

How many spacers do you have under the stem. The bars will become closer on slacker angled headtube of the Fugio the higher you have them and the stem will have slightly less drop (assuming stems are same angle)

You must also be higher off the ground on the Allez as headtube is longer but stack is same so Allez must have less BB drop (15mm). Being higher off ground can lead to a feeling of being sat on top of the bike rather than ‘in’ the bike and more stable.