I’m interested in getting a bike mail order so have been trying out some bikes that have a similar stack and reach.How different will the following two bikes likely be. The one I tested out today had the following geometry.
Stack 598mm
Reach 384 mm
The one I’m interested in but not tested is:
Stack 579MM
Reach 387MM
Head angle on both is 72.5 the one I tested had a seat tube angle of 73.5 the one I want on line 72.25 so again not much in it.
Other geometry is:

Tested bike: Chainstay Length 422mm, Head Tube Length 163mm, Seat Tube Length 500mm, Top Tube Length, Horizontal 561mm, Wheelbase,1014mm BB drop 85

Mailorder one I want:Chainstay Length 424mm, Head Tube Length 154mm, Seat Tube Length 570mm, Top Tube Length, Horizontal 568mm, Wheelbase,1020mm , BB drop 69

Is there likely to be a noticable big difference. The biggest difference I can see is the length of the seat tube of 7cm and the BB drop.
Any help and advice would be brilliant into how they will differ. I’m hoping not too much as the one today felt good but the mail order one is a much better spec for similar money.

I assume road bike with that geometry. Seat tube difference can be down to compact frames, but get the ‘virtual’ seat tube comparison.

Main measurement for road bikes is top tube and seat tube. My road bikes are around 73 degrees and I cant tell much difference between the three.

Both are gravel bikes. One I tried out today was spesh Diverge, Mail order Planet X Space Chicken

Your BB drop is a bit of a difference. I doubt you’d notice much. Chose the best spec for the cash (PX I guess). You pay a big premium for Spesh.

I’ve just written a load of stuff and ST ate it… sheesh

The summary was… the reach is very similar but the mail order has:

– a lower front end
– a slacker seattube, so you may need an inline post
– the BB drop could be a data error..

Lower stack will increase reach, so if you put enough spacers on the steerer of the shorter stack bike, until you get the stems at the same height, you’ll probably find the reach is shorter. So the taller bike with the shorter reach might feel slightly longer.
The slacker seat tube angle will make for a longer ETT again making that bike feel a bit longer, unless you move the seat forward to compensate.
So swings and roundabouts

BB drop will make you feel like you are sat a bit more “in” the bike rather than “on” the bike and combined with longer head tube makes up the 20 stack difference so with same amount of spacers you will be more in the bike but with higher bars (relative to crank).

However, which a 20mm spacer both bikes will be similar enough to probably not really notice after 10 minutes riding them

Thanks for the feedback guys. I’m pretty new to this so bare with me. The one I tested today has a slightly slacker seat tube (73.5 v 72) and is also the taller bike with a slightly shorter reach . So this bike might feel longer than the one not tested.

SO id be right in thinking that if the bike todday felt fine a few tweeks on the other would have it somewhere the same. I was worried that both bikes might be miles off and I would feel like I was on a bike totally wrong sized.

One degree difference is a cm at the bars or saddle. So one has a saddle a cm further forward. You can correct for this by mounting the saddle relative to the BB (5cm set back is typical). Of course the wheel positioning won’t change so there will be a slightly different weight distribution between front and back. The steeper seat tube will feel a little more planted.

The 72.5 head angle is really relaxed road bike, so both will handle fine. A bit like a Giant Defy to be honest. The difference in stack just means one will need spacers to raise the bars. For gravel, a longer headtube is preferred and a low stack may prevent bars above saddle.

People think too much about spec. If the one you test rode felt really good just buy it. A different bike will feel different so you might end up with something not as good as what you tested.

You say you are new to this, so.

Which ever one you buy, a few tweaks and 5 rides will mean you are ‘used to it.

Then you can start to figure out what you’d like from your next bike.

If you are thinking you’ll buy this and it’ll be job done you may find you are mistaken.

In 3 years time you’ll have 4 bikes, a divorce and a massive smile on your face.

Welcome to cycling.

My 58cm Cube has 388mm reach; 610mm stack; 73 seat tube angle; 72.5 head tube angle. 110mm stem -6 degrees.

Normally, I’d have 20-30mm of the 80mm of spacers above the stem, but I had a major lower back episode recently so I’ve put all spacers under the stem (not an issue as steerer is alloy, not carbon). http://yojimg.net/bike/web_tools/stem.php says that has changed reach/height by -6/+19mm respectively.

I’d probably cope with the test bike, with all spacers under the stem, but I’m not confident my back would be happy with the extra stretch of that Space Chicken frame… But flipping a 110mm stem to +6 would raise the bars 22mm, so it might work (albeit at least a 5mm spacer would need to be above the stem as it has a full carbon fork iirc).

The difference in the seat tube is the most significant thing in that list, everything else is so close that it can be compensated for.

Will you be using spd’s as the slacker seat angle could easily mess with knee position, moving the saddle forward will sort that out but will also mess with the reach (not in the “measurement” of reach because many companies draw a vertical line from bb to top tube and then measure horizontally from that point to stem centre 🙄 but in physically sitting on the bike).

Get too far behind the bb and it feels like you’re on a Pedalo, too steep and the top tube or stem needs to be longer. I’m simplifying this but it is the most significant difference in the 2 bikes (I was the custom frame builder for a small company and have spent the last 10 years fitting customers onto road and other types of bikes).

Hey longsider

I think you’re looking at these two… https://geometrygeeks.bike/compare/on-one-space-chicken-2019-l-57cm,specialized-women-s-diverge-e5-elite-2019-56/

The Space Chicken will feel slightly longer (due to seat angle), lower at the front (due to stack) and you’ll feel more on top (due to BB drop) compared with the Diverge. The key is slightly… if you swapped back and forth, you’d notice it. After 10 mins riding you’ll have settled into whichever you’ve chosen!

Of these differences, I think it’s the BB height that’s most significant – trading more pedal/chainring clearance for the feeling of stability and being ‘in’ the bike, as kerley says.

As others have said, you can easily adjust 20mm with spacers under the stem, sliding saddle fore/aft and/or swapping out a stem if needed, so don’t stress too much if it’s in the right ballpark.

Which one have you fallen in love with? Buy that.

Bob

Thanks everyone, some really good advice. I feel more confident that the the space chick is not in the wrong size ball park for me , which is good as it’s the one I want to go for.