Flat-Bar Road Bikes - Sizing and position

[KMKM]

Hi,

When I bought hybrids the bike size I got (and which most meaures recommend) 18"

I now have a Flat-Bar Road Bike (Decathlon B'Twin Fitness 2) and the size I was recommended to get is considerably larger than this (54cm) which is about 21".

I have looked on Evans Cycles website and it gives a similar type of size recommendation for road bikes.

• Is this usual?

• Is the flat-bar road bike positioning meant to feel like a cross between a hybrid and a racer with drop-down traditions bar and brakes? So basically in between and upright position and a crouched forward position?

Thanks

 

[MacB]

try looking at the effective top tube lengths and comparing those.

 

[HJ]

Just in cased you are not sure what MacB means, he means this...

I had to look it up too

 

[MacB]

Just in cased you are not sure what MacB means, he means this...

I had to look it up too

sorry, not like me to give a short answer

 

[KMKM]

Thanks chaps.

And in terms of flat-bar road bikes, is the flat-bar road bike positioning meant to feel like a cross between a hybrid and a racer with drop-down traditions bar and brakes? So basically in between and upright position and a crouched forward position?

 

[Norm]

I'll leave aside completely the question of the difference between a "flat barred road bike" and a hybrid.

You also haven't considered the other dimensions which make the difference between bikes. Rake and trail in the forks make the difference between a twitchy scalpel and a relaxing bike. Wheelbase also affects the feel and handling, and a longer wheelbase makes the bike feel smoother as the relative angle of pitching is reduced.

Sizing depends completely on what sort of bike you are getting and what you will be using it for, the charts, the guides, the "definitive" sites are basically, IMO, over-simplifying in a way that means people get a false sense of certainty without considering some critical factors in the selection.

For instance, I'm 5'11" with a 30" inside leg. If I wanted a Specialized Allez road bike for sprints, I should get a 54 as the bars would be lower, getting me down further but also bringing more of my core muscles into use for cycling.

If I wanted to do the equivalent of the London to Brighton every weekend, I'd need something with a longer top tube and higher bars, to give a position which is more comfortable for 5-6 hours in the saddle, so a 56 would be better.

So, there's two sizes for me in a road bike, depending on the purpose. If looking for a MTB, I'd get a smaller bike (to keep the top tube from the nut-crushing zone in an emergency dismount), if I was looking for a tourer, I might go bigger for a longer, even more relaxed position. What you've found is that a flat-barred road bike should be bigger than an MTB.

I've a friend who is about 5'6", who uses bikes as small as 48 for time trials, but as large as a 56 for the distances.

The good news is that, whilst there is no ideal size for anyone, there are also options on the seat position, bars, stem length etc to tailor a bike which isn't the perfect size.

Don't get hooked on the size. Get some test rides, spend at least an hour riding, get the one which feels most comfortable and then think about any tweaks needed over the next 200-300 miles.