Cannondale Synapse Sizing Help 51 or 54

pgodwin555

Another sizing question but just wondering if there is anyone running a Synapse and maybe similar sizing to me.
I am 171cm high but with 32inch leg (long leg short torso) and right in between sizing on most bikes. I actually found the Scott Addict Disc in 52cm the best fit so far but have a demo arranged on the Synapse on 54cm. Just interested in any input from people with similar proportions and what frame size you may be running. Do Cannondale usually come up small.?

keef66

I'm a bit shorter than you but similarly long legs / short torso, so I'm also usually between sizes.

Bike shops usually assume a 54 is the right size for me based on my height, but if a frame has racier geometry a 54 is usually too much of a stretch. I can make a 51 fit with spacers and a flipped stem so the saddle to bar drop isn't too big. With sportive geometry / shorter top tube / taller front end I can often get away with a 54, fewer spacers / normal stem.

Having said all that, the last time I sat on a Synapse the 51 felt perfect to me.

TLDR: try the Synapse in both sizes

pgodwin555

cool thanks for the input. Yes I was worried too about saddle to bar drop being too much on the 51. I demoed a giant defy in small and looks to be pretty much the same geometry as the synapse in 51cm but I only had 1cm of seat post left on the 44cm seatpost geometry was very aggressive position. Giant were adamant the small is the one I need. My gut says the reach is going to be too much but will see how I can get on and see what he LBS suggest ref fit. Just going to go with the bike brand that fits me best as they are all pretty similar in the rides I have tried so far.

First.Aspect

What stack and reach do you need.

Sorry.

First.Aspect

If you are happy with the 52cm Scott you should be okay with the 51cm Synapse. They are very different bikes though.

grenw

I'm similar size to you, maybe an inch shorter in the leg but not much. Can't comment on the Synapse but had a small Alu Defy and that fit nicely.

Now riding a small Endurace SLX which feels a little longer and lower and is perfect for me.

Seatposts for both were nicely in the middle of settings

gary_sparrow

Caad 12 or supersix size up big . I ride a 52 in a caad12 and I’m 5-8 . In a synapse I’d go 51 with a slightly longer stem. However my leg length is an inch shorter than you . The stack is quite large on the synapse . You could go either way but even with the 51 you won’t need loads of spacers . Look at the size of the head tube . It’s 14.6cm so even with the top cap and one 10mm spacer you be grand . Just stick a slightly longer stem on if you feel you need it.

Solis

I'm 174cm with 31 inch leg and my 54 Synapse is bang on if that helps.

dj58

pgodwin555 wrote:

cool thanks for the input. Yes I was worried too about saddle to bar drop being too much on the 51. I demoed a giant defy in small and looks to be pretty much the same geometry as the synapse in 51cm but I only had 1cm of seat post left on the 44cm seatpost geometry was very aggressive position. Giant were adamant the small is the one I need. My gut says the reach is going to be too much but will see how I can get on and see what he LBS suggest ref fit. Just going to go with the bike brand that fits me best as they are all pretty similar in the rides I have tried so far.

I realise that you are not buying a Defy, but I would query their advice, like you I have long legs/arms in relation to my torso and overall height. Giant size charts have me on a small frame, however I found the saddle to bar drop too much for my liking, would also need a longer/flipped stem. Tried the medium frame with 54.5cm TT and 16.5cm HT with 10.0cm stem and that fits me better. They should have tried you on the medium bike as well.

As you say the geometry is similar between the two brands, and you are trying both sizes, so you will know which you prefer after you sit on/ride them.

W12_Lad

I also have long legs. I'm 5'9" with a 33" inside leg.

This is a 54cm 2017 Synapse set up for me.
You should be aware that the 54cm and smaller come with a 300mm seat post which would probably be too short for you. It was miles too short for me, but the shop were fine about it and sent me a longer one.

Hope that helps.

frankcannondale

I am 170cm tall and use a 51cm Synapse fits perfect. The Giant would also be a Small.

gary_sparrow

Never rode a synapse but I will on holiday soon in the canaries . The geometry has changed a bit on the carbon synapse over the last couple of years with reach and toptube lengths .