Gravel vs Road Bike Fitting

[cd_davis]

Looking at gravel bikes and was wondering if sizing should deviate from road bike fit, specifically top tube length and seat height. I seem to be between sizes in the Trek model I'm considering. Appreciate to learn from the experience of the Forum.
Thanks in advance,
Chris

[Gummee]

IDK about anyone else, but I'm pretty close in position across all bikes: road, CX, and mtn. It's where the body feels best.

M

[Lovetoclimb]

I ride the same size frames but may use a 1cm shorter stem or one with less angle. For example 120 -6 der on a road bike, and 110 0 degree on a gravel bike all other things being equal. Add some flared out dirt drop bars, nothing too flared like the widest Salsa bars, just a few degrees.

I prefer a little more upright position to encourage my weight being more even over the wheels. We have a wide array of gravel here in WNC and TN, often loose and unpredictable. A hard tail 29er is equally at home most days.

[Mzilliox]

im pretty much same fit with a touch less drop on gravel. my dedicated gravel bike used the geo from my Goodrich Roadie, with a taller HT to get the front end up a touch. running 9-10 cm drop on the road bike and more like 6-7cm drop on the gravel

[John H.]

Saddle position should be the same as road bike.
Bars- somewhere between same a road position, or slightly taller/shorter.
I like my gravel bike to be about 1cm shorter and 1cm taller than my road bike.

It can also be helpful to achieve this position with a slightly shorter stem- A shorter stem will allow for longer front center- Gives a bit more downhill stability and also less toe clip overlap.
You can end up with more overlap than you expect with big tires-

[semdoug]

If you are trying to match a trek gravel bike sizing to a specific road bike there might be a difference in head and or seat tube angle impacting other measurements.

[Duende]

Originally Posted by semdoug

If you are trying to match a trek gravel bike sizing to a specific road bike there might be a difference in head and or seat tube angle impacting other measurements.

Bingo! My gravel bike head tube angle pretty much split the difference from me needing to go shorter on my stem. Longer length of HT kept me from going higher.

Honestly the only “fit” change I’m doing is maybe a hair lower on my seat post height.

Been thinking about a dropper post too. Some of the descents around here can take you out pretty quickly. The roads just aren’t maintained. Riding single track is another reason, but that’s just me being stupid.

[dem]

I set mine up identical to my road bike, taking into account the various angles (I have a spreadsheet that does the trig, although I cannot recall where I downloaded it from.)

Given I'll spend 6 to 10 hours on both bikes, changing fit seems like a poor idea. If I liked a shorter stem, I'd put a shorter stem on the road bike too.

[happycampyer]

Originally Posted by John H.

Saddle position should be the same as road bike.
Bars- somewhere between same a road position, or slightly taller/shorter.
I like my gravel bike to be about 1cm shorter and 1cm taller than my road bike.

It can also be helpful to achieve this position with a slightly shorter stem- A shorter stem will allow for longer front center- Gives a bit more downhill stability and also less toe clip overlap.
You can end up with more overlap than you expect with big tires-

This is exactly my approach (or should I say, the approach builders I've worked with (Hampsten, Firefly) have taken). Keeping the front center consistent helps, especially since the rear center is usually a little longer on a gravel bike than a road bike due to slightly longer chainstays.

[Bob Ross]

From my sample of 1:

Recently bought a Cannondale CAADX. Spent a long time comparing its published geometry with the road bikes I currently own, and determined that their size 58cm would most closely match what I currently ride.

Unfortunately the size 58cm CAADX is sold out all over the country (!). LBS owner tells me "but I can get you a size 56cm by Friday...and btw, you always want to size down from road to off-road."

Well, that sounded like a load of sales BS to me, but he's a good guy and I knew if the bike didn't fit he'd take it back and Do The Right Thing, so I ordered the 56cm.

I'll be damned: This thing fits perfectly!

So there's that.

[Hakkalugi]

My road and gravel bikes have the same toptube length, but I’m running a 30mm shorter stem for gravel. It started as an experiment, and I noticed right off that with my elbows and wrists were much more comfortable on rough roads and singletrack. The stem was just one I had in the pile, it is nothing special, I tried it and liked it.

[MikeD]

1 cm shorter and 1 cm higher for gravel.

[Marc40a]

Originally Posted by Hakkalugi

My road and gravel bikes have the same toptube length, but I’m running a 30mm shorter stem for gravel. It started as an experiment, and I noticed right off that with my elbows and wrists were much more comfortable on rough roads and singletrack. The stem was just one I had in the pile, it is nothing special, I tried it and liked it.

I’ll have to measure to be sure, but I’m in that ballpark as well. I’m also 1 cm or so higher than my road bars (which, incidentally, are quite high at 2cm drop from seat level) I don’t have a ‘gravel rig’ per se, more of a drop bar mountain bike. The bar/stem fit adjustment allows me to descend or deal with technical sections in the drops. It also allows me to shift my weight around the bike to find a sweet spot for traction when climbing or to get my ass behind the seat for steep drop-offs or technical descents.

[wallymann]

my gravel position is 100% identical to road -- which is to say "pretty racy", but i tend to ride forgiving/hard-packed gravel roads.

as others have suggested, my gravel frame has a longer front-end so my stem ends up ~1cm shorter than i'd typically need on road bike geo.

Originally Posted by cd_davis

Looking at gravel bikes and was wondering if sizing should deviate from road bike fit, specifically top tube length and seat height. I seem to be between sizes in the Trek model I'm considering. Appreciate to learn from the experience of the Forum.
Thanks in advance,
Chris