Cycling geometry questions

[Daninplymouth]

Hi, il start off by saying I’m not sure if this should be here or in the bike advice forum see please move if appropriate.
I’m just trying to get my head around how bike geometry effects the feel of the bike, so if anyone has any input on the examples below I’d appreciate any feedback.
My simple mind tells me that if your seat height and bar height is roughly the same then do different frame shapes and angles have any impact?
My issue is I ride a 60cm Caad13 which I feel is a bit big so looking into something a little smaller and more endurance based. As my rides are now a lot longer than I planned I would do, but with the current situation test rides seem bit of a no go.
image below shows my caad (light green) overlaid against The 58cm synapse (dark green) and ribble endurance (red)

Here is the caad vs synapse

And caad vs ribble

what I struggle with a bit is the ribble they call an endurance but has a much lower stack than my current frame, but would the slightly higher seat angle position you up closer to the bars?
Also the smaller synapse has a stack very similar to my bike although the frame is more compact and it has a slightly less reach to the bars.

I have put a smaller stem on my caad which has helped a lot but I do still get an occasional pain in my neck, not sure if it is all attributed to cycling or no. But seeing as I’m looking for a new bike I’d like something a bit more comfortable, do you think either of the frames above would offer an improvement on this?
Thanks

 

[wafter]

You're right that seat tube angle (or rather effective seat tube angle) will affect the reach to the bars; however, remember that your saddle height and effective seat tube angle / saddle layback should be set (independently of what's going on at the front of the bike) to give correct / comfortable lower-body geometry / positioning relative to the bottom bracket. As such, in the horizontal axis at least reach can be taken as a viable, singular measure of how stretched out you'll be.

It's also worth remembering that when on the bike pivoting the upper-body about the hips or arms about the shoulders describe arcs that move the hands forward as well as moving up; so more stack can allow longer reach for the same level of comfort.

FWIW, from your requirements and the diagrams posted (nice illustrative tool) I don't think either frame will necessarily give you what you want. The Synapse has a fractionally shorter reach at a similar stack which is moving in the right direction but probably not hugely significant - especially if you've already shortened the stem on your existing bike. The Ribble looks well off with a similar reach but much lower stack so offers a less relaxed geometry than your current setup.

Of course it pays to bear in mind that frame reach and stack only tell half the story since the actual position of all the frontal contact surfaces are defined by the size of the stem, bars and shifters. If you can be arsed / can get the appropriate bar and stem dimensions you can knock up a spreadsheet to calculate reach and stack at the bars, which is far more indicative of real-world use.

Best advice I can give is to continue to play about with your own gear - for a start try flipping the stem (if it's not already) to give it an upward angle and reduce both your stack and reach somewhat and should help the situation with your neck

 

[Daninplymouth]

Thanks I have already flipped the stem and played about with moving it up or down the stack. Think that’s part of my problem which I’m struggling with as I done 50miles on Tuesday pretty pain free then I raised the stem up 5mm and did 30miles yesterday and it was quite sore.
Strange how ribble class it as an endurance built for covering the miles but to me the set up seems quite aggressive.
Also I think some of my problems come down to the state of the local lanes as they are quite beaten up and I find that if I’m around town more then it’s not as bad, this is part of the reason I want a carbon or ti frame next.

 

[vickster]

Thanks I have already flipped the stem and played about with moving it up or down the stack. Think that’s part of my problem which I’m struggling with as I done 50miles on Tuesday pretty pain free then I raised the stem up 5mm and did 30miles yesterday and it was quite sore.
Strange how ribble class it as an endurance built for covering the miles but to me the set up seems quite aggressive.
Also I think some of my problems come down to the state of the local lanes as they are quite beaten up and I find that if I’m around town more then it’s not as bad, this is part of the reason I want a carbon or ti frame next.

Do you ride in glasses and/or a helmet. Both can affect head position and lead to neck pain as you crane the neck to look ahead (or side ways/backwards).

How's your fitness and core/back/neck generally - do you do stretches/pilates/yoga? Sounds like you are tall, it was explained to me by a neurosurgeon that neck issues especially are more common in taller folk as we spend more time looking down!

Can you put fatter tyres on the bike for a bit more comfort (Merlin have some 28s for £12, not the quickest or lightest but might offer benefit over 23s/25s). Frame material alone won't smooth out crap road surfaces unfortunately!

 

[Venod]

I have been looking at the Synapse geometry, each frame size has different geometry, allegedly to give the same ride feeling, I don't know how true this is, have you looked at the Cannondale sizing charts and recommendations for your height, it seems pretty accurate for me, but I am of average proportions, I fall at the top end of 54 and bottom end of 56 for the Synapse, the measurements closet to my On One Pickenflick medium (my favourite ride) are 56. beware using the Geometry Geeks comparison site, as an example the virtual top tube length they quote for the Pickenflick is the actual top tube length.

https://geometrygeeks.bike/

 

[Daninplymouth]

I am about 188cm tall, which on the cannondale sizing puts me right on the lower end of the size 60.
I already have 28mm tyres.
Fitness is ok really, getting better I used to do a lot of weights in the gym but am now stretching and cycling most days.
Just a bit frustrating as some days I’m fine and others it really plays up, I have played around with numerous stems, came with a 110 standard but have also tried 100 currently have a 90 fitted.
so just trying to sort out my best positioning for when I order my new bike, which at the moment I’d rather do sooner rather than later as all I can do at the moment and for the foreseeable is cycle everyday

 

[Daninplymouth]

Hi, yes I have looked at the sizing charts. For my caad I am right at the lower end of the 60, the synapse at 58 puts me at about middle of the range which is by I think it should fit me better

 

[Venod]

I would suggest 58 is your Cannondale Synapse size going on this chart.

https://www.cannondale.com/en-gb/bi...arbon/synapse-carbon-disc-105?sku=c12350m1051

 

[Hugh Manatee]

Is Baretto's (sp!) still the local 'Dale dealer?

 

[Milkfloat]

For me geometry plays a big part on getting a good bike fit, but does not tell the full story of how a bike feels. Materials, tube design and construction method plays a huge part. Just as much would be tyre size and pressure. To add, I am 194cm and ride a 58cm Synapse, the frame is on the small side, but that is how I like it.

 

[Daninplymouth]

Thanks all.
Think I do have my heart set on the synapse and I can’t see how a slightly smaller carbon endurance based bike can be any less comfortable Than my Ali caad

 

[Daninplymouth]

I have done some more adjusting on mine, first I raised the stem up the stack but this caused a real tight spot in my shoulder. Now I have flipped the stem so it’s now a negative rather than pointing up and i fitted a 10mm longer stem. In theory this should have made it more uncomfortable but it was a lot better. Part of me thinks it was more my positioning and not engaging more core as needed as I have been making more of an effort to use this rather then holding myself up on my arms.
It now looks as though a lot of the synapses are selling from dealers so might have to give the ribble a try.
has anyone here rode the ribble endurance sl disc?

 

[Daninplymouth]

I have been having another thought too and sticking with cannondale but going down to a 58cm, the supersix would be in budget and offers me what I’m looking for in carbon and disc brakes. The 58cm seems to sit half way between my 60 and the XL ribble if anyone has any feedback on these?
Still confused on the ribble as it’s called an endurance, I know it’s at the racier end. but they also do an electric version to help so you’d think it would be comfortable and help people less experienced or older but the geometry looks long and low 🤷🏼‍♂️

This is how the 58 Cannondale’s compare

 

[GravityFighter]

I'm not an expert on bike fit, but I do know most Cannondales tend to size up large compared to other brands (they generally have a longer effective top tube).

I ride a 54cm CAADX and Synapse, but am usually a 56cm frame in Trek, Specialized et al.

So dropping from a 60cm frame to a 58cm in Cannondale would seem to make sense OP!