Silver Steve

I have been professionally fit for my road bike. It's great. Comfortable, fast, etc.
I purchased a gravel bike a while back and set it up with the same fit measurements using bikegeocalc.com to overlay both bikes.
I'm scratching my head because I just can't get comfortable on the gravel bike. My hands get numb and my neck and back are fatigued.
I've tried shortening the stem, slight adjustments to the saddle (tilt, height, fore/aft), and different shifter positions. None of these adjustments really helped that much.
Is there a general rule of thumb in setting up a gravel bike with known road bike fit measurements?

Thanks

Polaris OBark

Some gravel bikes have road-like geometry, and some are much more slack. Reach and stack, front to center, saddle tip to brake lever hood, and drop from saddle to bar tops are good numbers to try to match. But before you do any of that, make sure you have the correct saddle height and fore/aft, so that you are balanced. If you don't get that right, you will be hurting in much the way you describe.

Silver Steve

I have the saddle set up with the same offset (fore/aft & height) as my road bike. But now that you mention it. Will that differ between shoes and pedals? I have Specialized S-Works 6 road and S-Works 6 MTB shoes. The pedals are Ultegra PD-R8000 and XTR PD-M9000 respectively.

Thanks!

Iride01 

What two bikes? The 2106 [2016] Giant TCR and the 2021 Huffy?

Quite a bit of difference between the two bikes. Though Huffy doesn't seem to make the geometry spec's available. However I'd say the Huffy has a way higher stack than the Giant TCR.

Also there are handlebar differences of a flat bar to a drop bar. I'd imagine the flat bar might have your hands spread further apart. The difference between 42cm and 38cm drop bars on my current bike made a difference for my aching shoulders on long rides.

And depending on how detailed you got in making your own measurements between the two, you may well have missed a few things that significantly alter what you came up with to compare your bike geometry calculations.

Calsun

What matters is the seat post to handlebar distance. In some cases the handlebar width may also be a problem if your hands are closer together and you need to scrunch your shoulders to adjust.

I would get up on the saddle and then move into a relaxed position with your hands on the brake levers and then see what needs to be changed. On a gravel bike there are advantages to having a dropper seat post to get it out of the way on downhill sections. It is standard on the Specialize Turbo Creo gravel bikes.

Part of the problem may be your lack of experience with the bike and on riding off pavement. You may be more tense while riding and may need to concentrate on relaxing your shoulders and neck and changing your posture and hand position on the gravel bike in the same manner you can do without thinking on your road bike.

Polaris OBark

The stack height is lower for XTR pedals (and Dura Ace) than it is for Ultegra and XT. Beyond that, I have no clue.

Silver Steve

The gravel bike isn't actually a Huffy It's a Carbonda 696 with Huffy livery.

Here's the 2 bikes' measurements overlaid. I currently have the gravel bike set up with a little shorter reach and a little more rise...


And here are the two bikes for reference...

Iride01 

It's very likely just the camera angle, but those look like pretty wide handlebars. Not quite sure about the Giant either, they look a tad wide too, but certainly not quite as wide.

I'd always heard that handlebars for a road bike shouldn't be any wider than the distance between the shoulder's acromion process. Judging by the bars I see on many road bikes today, I'd think that many must be going by overall width of the shoulders including the muscle mass. As I mentioned before my new bike came with 42 cm bars. My acromion process measures 40 cm, I changed to 38 cm bars as were most all my other bikes prior.

Even the manufacturers seem to be putting wider bars on them than they use too. Perhaps it's so we can have room for all the gizmos we like to put on our bars now.

The effect of going too wide with your hand position is that it braces you too strongly against the road forces and swaying of you or your bike as you pedal. And your shoulders/upper back and arms bear all the brunt of the forces. If you have a really good bend in your elbow, then probably not so, but that might mean a feeling in your elbow like shin splints later on.

I experienced both when I had wider bars. I first went to a shorter stem to give me that better bend in my elbows. But still wound up getting narrower bars and all was good for me again. I eventually went back to the longer stem.

I'd think the same will hold true for a gravel bike as it would a road bike.

Silver Steve

It's interesting you mention the bars. I actually went as far as swapping out the bars on the gravel bike to the exact same bar that's on my road bike. They are both 42mm. Thanks for sharing your findings using a narrower bar. I was curious about using a narrower bar for the gravel bike to provide more "support". But I figured I'd try and reduce the amount of variables between fits. The saddles are also the same between bikes.

One thing I did notice between the setups is the shifter shape. The Ultegra hoods (disc/mechanical) are much wider than the Dura ace (Di2/rim brake). I have small-ish hands and find the Ultegra much less comfortable.

RB1-luvr

This is what I was going to say. When I ride my gravel bike on the road, I have no discomfort (I'm a roadie). When I ride it on gravel paths for 2+ hours I get uncomfortable in my shoulders, neck, wrists and butt. I think it's just not being used to the extra demands of gravel riding.

One thing that has helped the hands, wrists and shoulders anyway, is adding these to the bars. It allowed me to loosen my grip and relax. They go under your bar tape.