measurement of handlebar stem

[alecstilleyedye]

between which two points do i measure the handlebar stem to ascertain its length (so i can order a new one the same length).

cheers in advance if anyone knows.

 

[Smokin Joe]

Centre of steerer to centre of bars.

 

[Dave5N]

Alex - centre to centre.

 

[Foghat]

If you're really particular about the dimensions of your bikes and geometry of your set-up, then bear in mind:

• one manufacturer's 130mm (or whatever) may not be exactly the same as another's
• oversize bars are about 6mm larger in diameter than 'ordinary' bars, so the centreline of the oversize bars will be 3mm further away, increasing reach by the same amount

Maybe this won't concern you, but I have all my bikes set up to 1-2mm tolerance in the critical dimensions; this is because I notice the difference otherwise, and don't feel right if they're out.

 

[mickle]

• one manufacturer's 130mm (or whatever) may not be exactly the same as another's
• oversize bars are about 6mm larger in diameter than 'ordinary' bars, so the centreline of the oversize bars will be 3mm further away, increasing reach by the same amount

Shirley a centre to centre measurement is a centre to centre measurement irrespective of the diameter of bar or steerer.

 

[Foghat]

Shirley a centre to centre measurement is a centre to centre measurement irrespective of the diameter of bar or steerer.

Yes, that's true. But manufacturers' centre-centre measurements are more nominal than precise, so they can't be trusted (certainly not between manufacturers, and not even between different models of stem by the same manufacturer) and should be checked manually....if accuracy is important to you.

The point I was really making is that when measuring the critical horizontal centre-of-BB to bars dimension (assuming saddle is already correctly positioned behind BB), it is far easier to do it from the front of saddle to the rear of the bars at the centre next to the stem with the wheel dead straight. When doing this, one should factor in the fact that oversize bars' centrelines are 3mm further away than 26.0mm bars.

 

[Smokin Joe]

I don't get that.

The centre line will be exactly the same distance from the tip of the saddle no matter what the diameter of the bars.

 

[Foghat]

I don't get that.

The centre line will be exactly the same distance from the tip of the saddle no matter what the diameter of the bars.

It's all to do with how one practically makes the measurements.

As it's far easier to measure the distance-to-bars dimension by using the end of the tape abutting the rear of the bars, and the flat of the tape to visually line up the front of the saddle with a millimetre increment on the tape, one needs to be aware of the additional 3mm on oversize bars.

You could use the tape the other way round, or try the end of the tape where you think the centre of the bars is, but estimating by eye where the centre of the bars is is harder, and in the second instance it's difficult to keep both hands exactly in place when looking closely at one hand.

As most stems seem to be available in 10mm increments, those 3mm can be quite important in attaining the right reach.

 

[briank]

Hold up, Joe

Distance from tip of saddle to centreline of bars=dist from tip of saddle to reasmost edge of bars + radius of handlebar tubing

Since O/S bars are about 6mm greater diameter than 'standard' ones, the radius is 3mm greater so the centreline is 3mm further from the tip of the saddle.

Yes?

 

[Smokin Joe]

Fcuk me, this is getting complicated.

The distance from the tip of the saddle to the centreline of the bars will be the same whether the bars are 1/4" in diameter or two foot.

Think about it.

 

[alecstilleyedye]

i found that, after redoing the brake cables (and hence redoing the bar tape), i got the shifters in a more comfortable position, so i'm putting the new stem on hold.

i'll bear all the advice in mind though. cheers

 

[02GF74]

centre to centre. regardless of saddle diameter, shifter position, lottery numbers, bar diameter, weather outside, number of wasps in your lager .......etc

 

[Dave5N]

centre to centre. regardless of saddle diameter, shifter position, lottery numbers, bar diameter, weather outside, number of wasps in your lager .......etc

swoti sed