31.8 vs 31.7mm bars/stems

DiscoBoy

I currently have a 31.8mm bar and stem.

If I were to buy a 31.7mm set of bars (Deda Presa carbon) would I also need to buy a new stem?

ugo.santalucia

Have you ever seen 1/10 of a millimeter? :roll:

My guess is NO

DiscoBoy

ugo.santalucia wrote:

Have you ever seen 1/10 of a millimeter? :roll:

My guess is NO

That's my guess too, but I'd like more than a guess when it comes to my shiny new parts

drlodge

If its a standard clamping arrangement (front plate with 4 screws sandwiching the bars), it'll be fine.

brearley

I use 31.7 bars with 31.8 although having read up online deda's 31.7 is 31.75 rounded down whereas most 31.8 bars are 31.75 rounded up. Maybe that's what they do with their product weights and tolerances too

drlodge

Probably 0.05mm is within manufacturing tolerances...I had a new 31.8 seat post measured the i/d of the seat tube...31.6mm Damn I thought, I got the wrong one. But it fits just fine, probably just some dust making the measurement inaccurate.

DiscoBoy

Okay thank you all

drlodge

Well the seat post fitted just fine after I used a crow bar to widen the seat post :shock: :roll:

cq20

They are the same. Like many things in cycling e.g. chain links, the actual size is in Imperial units and in this case it is 1.25 inches. This converts to 1.25 x 25.4 = 31.75mm, which some manufacturers call 31.7mm and others call 31.8mm