Bike sizing for the longer leg... Cannondale synapse?

by zzr-matt   January 4, 2014  

I'm coming over from mountain bike riding to road riding and figured it was time to get something that doesn't have as much tyre noise as a old landrover on the road.

I'm 191cm with a 92cm inseam and long arms too.

Today I was fitted on a 58cm Cannondale synapse, knee angle was good on the measurement gauge and my knee came above the ball of my foot on the pedal axle using a plumb line with horizontal pedals.

I felt a little stretched out but my back was apparently quite upright and when in the hoods the front hub was visible about half way up the stem between the steerer and bars. I assume my flexibility will improve with time allowing me to flatten my back angle. Would that imply that I need a 61cm frame with a shorter stem to start to give me somewhere to go in the future?

They unfortunately didn't have a 61cm in stock to try.

Is the hub visibility in relation to the bars rule of thumb worth paying attention to?

10 user comments

Oldest firstNewest firstBest rated

61cm will be the better option for you however cannondales do tend to be longer than other brands such as trek, if your flexibility is an issue get a shorter stem and dont alter the drop right away.

too many people drop there bars down because its what the pros do, but half the folk are no where near flexible enough for this.

for the reach, you dont want your arms locked out, make sure there is a little bend.

posted by Lost faith in t... [120 posts]
5th January 2014 - 11:51

1 Like

I've never heard that hub rule of thumb, but I'm a similar size 194cm and long legged too. A CAAD10 60cm fits me perfectly, once I went to narrower bars. Cannondale scale up the bars a lot more than other brands. I had a 46cm c2c on mine. So check the bar width if you are not broad shouldered.
Wide bars effectively lengthen the top tube, but cause shoulder pain instead. I really like my CAAD10, great bikes

Cannondale CAAD10, Condor Terra-X and an orange Brompton.
Ride for East London Velo

zzgavin's picture

posted by zzgavin [208 posts]
5th January 2014 - 11:53


It's a long time since I first heard that rule of thumb and not thought about that in years. After reading your post first thing I checked my bike this morning, hub exactly in line with the bars with my hands resting on the hoods. I'm slightly taller than you but my legs are slightly shorter. Not on a Cannondale but riding XL / 61 cm frame.

If you felt stretched on the 58 then maybe that's the right size for now. Any improvement in flexibility won't come overnight and if you're not comfortable then on the bike initially then you're less likely to enjoy it.

posted by Bagpuss [104 posts]
5th January 2014 - 13:07


Thanks for your comments guys.

Does the fact that the hub is appearing between the stem and bars imply that the reach is too far or too short? The guys in the shop said that this implied I needed a longer stem which would flatten my back but I can only see that this would move the hub further behind the bars rather than closer to them?

My arms are around 760mm long and I'm 550mm ish across the shoulders if that adds to any advice at all!

posted by zzr-matt [3 posts]
5th January 2014 - 19:40


Lost faith in the brand wrote:
61cm will be the better option for you...

I don't see how anyone can make that judgement without seeing you on the bike in both sizes. It's worth remembering, though, that it's much easier to make a frame that is a bit too small fit than one that is a bit too big, as you can always extent the seatpost and stem, but there are limits to doing the opposite.

posted by lc1981 [55 posts]
5th January 2014 - 19:49


Unfortunately I'm not doing too well at finding a bike shop which has both sizes in stock. From what I have seen most places will tell me the best fit is the bike that is in stock which is why I am asking for some general advice on here.

posted by zzr-matt [3 posts]
5th January 2014 - 20:03

1 Like

Are you anywhere near Ludlow? Epic Cycles are known for being good at bike fitting and they usually have a big stock of Cannondales.

posted by lc1981 [55 posts]
5th January 2014 - 20:19

1 Like

I really wouldn't get hung up on your view of the hub position. I only remember that fitting gem from rigid MTBs years ago, on a road bike with drop bars and the multiple hand positions they offer then I think it's not really applicable as you'll move your hands around a lot as you ride altering your view, the angle of your back etc.

Looking at the C'dale site there's 2cm difference in the horizontal top tube measurement between the sizes. Doesn't give the stem length for each one, so hard to guess which would be best.

However, with legs that long would it be fair to say you've got a short (it's all relative Wink ) torso for your height, if that's the case then the slightly shorter frame makes sense.

Have they got a demo bike you could hire and go for a proper ride?

Or, try something like the Bike Fast Fit on an iPhone/iPad in the shop. You'd need to stick the bike on a turbo but if the shop want to make the sale and you take a packet of biscuits then they might go for it.

posted by Bagpuss [104 posts]
6th January 2014 - 17:51

1 Like

because there are formulas you can use to size up the bike if you know there inseam.....

also there is limits to both being to big or too small a bike, not just big.

saying that you can always go up or down a size on a road bike and 99% of the time adjust it to fit......

posted by Lost faith in t... [120 posts]
10th January 2014 - 12:18


the hub theory works for some but at the end of the day its just a ballpark estimate that doesn't take into account individuals needs (ie flexibility). Knee over spindle also only has limited theory and to many is flawed. It is tricky when you are not average height. I'm 194 with 100cm legs so I struggled getting something to fit as the bigger you get, the longer the top tube which wasn't actually what I needed.

It would sound to me like a 61 might be too big if you are stretched out now, you can go up to a 14cm stem on a road bike, and many find a longer stem nicer as you get more relaxed handling. Only way of knowing is to sit on one and thats your problem, 61 cms cannondales are not widely stocked. No one can give you a firm answer only view I'm afraid.

'It's the closest you can get to flying'
Robin Williams response when asked why he enjoyed riding so much

posted by Simmo72 [456 posts]
10th January 2014 - 13:23