Stack and reach - im confused

First.Aspect

TimothyW wrote:

First Aspect wrote:

TimothyW wrote:

You want a stack around 580 and a reach of 370 on the soma bike?

In that case you'll want the stack 582 and reach 382 size 54, and a 1cm shorter stem than usual.... or a different bike.

I wouldn't recommend buying any size of bike without a test ride or the option to return it if you don't get on with the fit.

I'd opt for the size down actually. The 54 is too big and I'd need to pull the seat forward quite a bit. Might be okay with a shorter than normal stem you are right, but I like a normal stem thanks. Isn't that the point of getting the right size of frame?

Better than the last one though.

It's better to test ride yes. Not always possible these days.

If you want the same stem as you consider 'normal' then get a bike with the same stack and reach as 'normal'. This was covered where I said 'or a different bike'.

Pulling the saddle forward is considered a no-no because this would imply pulling it out of the optimal position, although I appreciate this is a bit of a fuzzy concept. Certainly my experience is that I was happier overall once I identified the bike which had the saddle position I liked most, and replicated it on my other bikes.

While sizing down is often the best option, you've mentioned in a previous post that you choose bikes based on looks - for a lot of people this means getting the frame size which allow you to 'slam" the stem even if it means a slightly shorter stem than usual.

In this case, the size down doesn't reduce the reach (so you'll still probably want the shorter stem) and you'll also need extra spacers under the stem.

This is nonsense.

drlodge

Now I'm confused.

On reflection, I think reach is as useful as eTT, more or less.

Reach gives you the position of the bars, (for a given length stem) from the BB. eTT gives you the position of the bars (for a given stem length) from the seat post...which, assuming the frame size and seat tube angle are in the ball park, is from the seat tube a bit lower than the saddle so is a proxy for distance from the saddle position. eTT might therefore be regarded as a bit more useful than reach, however frame size and STA will alter the accuracy of eTT.

I agree with Timothy on at least one point "Pulling the saddle forward is considered a no-no because this would imply pulling it out of the optimal position". The "correct" saddle position does not depend on the bar position so in independent of eTT, reach and so on.

proto

I'm with First Aspect on this. I've built loads of bikes over the years and I'm confident all I need is the ETT and head tube lengths. I've never considered Stack and Reach, just too confusing to me, whereas with TT and HT I know exactly what I'm getting.

Being an old fecker, I tend to look for frames with relatively short TT and longish HT. So I avoid Ridleys, Boardmans and Giants, their geometry just doesn't work for me, top tubes too long. Bought a Ridley, knowing it was a bit stretched, but it was cheap and I was greedy. It was too stretched, so I flogged it smartish. Boardmans also have horrendously long TT's.

Head tube to me is important as I need the bars fairly high, and being a complete bike tart I don't want a load of spacers under the stem. Work around is shape of bars and 'shallow drop' style

Even lever hoods can make a difference. Shimano are ' longer' than Campag and SRAM.

So, with a known TT length, there's plenty of small adjustment with the following to get a good fit

1) stem height, length and angle
2) seat post 'layback'
3) seat height and position on rails
4) shape of bars
5) make/design of shifters

Not sure what Stack and Reach, or ETT measurements were taken into consideration when speccing Vos's Liv (Giant) bike, but shows that just about anything will work! Looks like a zero offset seat post and the saddle shoved as far forward as it will go.

https://goo.gl/images/TVp1g2

dj58

proto wrote:

I'm with First Aspect on this. I've built loads of bikes over the years and I'm confident all I need is the ETT and head tube lengths. I've never considered Stack and Reach, just too confusing to me, whereas with TT and HT I know exactly what I'm getting.

Being an old fecker, I tend to look for frames with relatively short TT and longish HT. So I avoid Ridleys, Boardmans and Giants, their geometry just doesn't work for me, top tubes too long. Bought a Ridley, knowing it was a bit stretched, but it was cheap and I was greedy. It was too stretched, so I flogged it smartish. Boardmans also have horrendously long TT's.

Head tube to me is important as I need the bars fairly high, and being a complete bike tart I don't want a load of spacers under the stem. Work around is shape of bars and 'shallow drop' style

Even lever hoods can make a difference. Shimano are ' longer' than Campag and SRAM.

So, with a known TT length, there's plenty of small adjustment with the following to get a good fit

1) stem height, length and angle
2) seat post 'layback'
3) seat height and position on rails
4) shape of bars
5) make/design of shifters

Not sure what Stack and Reach, or ETT measurements were taken into consideration when speccing Vos's Liv (Giant) bike, but shows that just about anything will work! Looks like a zero offset seat post and the saddle shoved as far forward as it will go.

https://goo.gl/images/TVp1g2

Interesting, so does the Giant Defy, which has those characteristics not work for you then?

proto

No idea, tbh. Being a bike tart I only looked at the top end of the market, I wouldn’t have lowered my sights to a Defy.