HUGE help needed with bike size

donslow

Hey all, I’ll try keep this brief

Looking to replace my old road bike but I’m unsure of what size to buy so I’m hoping you lovely lot can help

I currently own a Planet X Pro Carbon which I THINK is a medium frame (top tube 52.5cm seat tube 48-ish cm)

From my limited experience with road bikes, as far as I can tell, this fits me ok, it’s certainly not uncomfortable to ride! Although I can see that I’m not due to a slight bend in the elbows, I feel a little stretched when riding on the tops, wondering if I just have the bars too low or levers too far forward?! But when I stand to sprint, I think more room would be beneficial (I often knock my knees on my phone which sits on a quadlock adapter on my stem)

I myself am 5’6” ish (maybe MARGINALLY shorter) with a 29” inseam

I’m looking to buy a cannondale alloy synapse but am getting so much conflicting information as to which size would be my best bet, unfortunately no cannondale stockists or dealers within about 90 miles of me so am left to buying online

So far I’ve found out the following
A 48cm frame would fit
A 50 / 51cm frame would fit
A 54 cm frame would fit

Can you appreciate my confusion?!

ANY help/advice would be massively appreciated

Many thanks in advance

DeVlaeminck

So what you are asking is what size Synapse would suit a typical 5'6 rider ? Well if you google cannondale size chart you are right on the border of a 50 or 52cm. The 52 says suits 5'6-5'7 whilst the 50 suits 5'4-5'6.

https://www.hargrovescycles.co.uk/media ... sizing.jpg

However as they don't make a 50 or a 52 Synapse but they do make a 51 I'm going to take a punt and say that is most likely your size - I'm not saying rush out and buy one based on that but if you could find someone with a 51 to sit on ?

donslow

To be honest I was erring on a 51 from what I had seen but just wanted to check for more opinions from people who know a lot more than I do ha ha

daniel_b

Greetings,

I am 5ft 10, with a 34" inseam, so my torso is around the same length as yours, but you have 5" less leg length than I.

I ride a 54cm Synapse, and could easily slam it if I wanted to - IIRC the TT on this is circa 540\545 which is pretty much spot on for me with a 100mm stem.

They have an endurance geometry, but I would wager a 54 for you would be bars higher than the saddle, which is fine if that is what you want.

However, as already alluded to, I would have thought the 51 would be the right choice for you, and be open minded about replacing the stem it comes with at some point - you can get them dirt cheap second hand until you have the perfect setup.

volvo_fatboy

Hi,

I am 5'7" with a 29" inseam and ride a Cannondale Synapse 2017 Alloy Disc as my winter bike. Its a 51cm and fits perfectly.

Hope that helps.