Stack and Reach: Why It's Your Best Friends

Which article are you referring to?

I want to compare frames, not fit a bike (hence the emphasis in my quote).

That quote you provided.

It's not really important on kid's bicycles, however on the bigger model, you'd expect them to provide such information as there are people who are shorter than average would like to know.

They're right it's not exactly comparable because the kids bike are designed purely for growing children and the geometry reflect this, not for an adult who finally stopped growing and required a proper fit (as in a bike that's comfortable, rather than saying they need a bike fit).

OK, but I still don't understand why it's not important for kid's bikes.

My friend's boy has a Dawes which is too big for him; he is in the middle of the size range for a Luath 24 and at the minimum for a Luath 26.

It seems sensible to me, to compare the Dawes to the two Islabikes and that the best way of doing that is with stack & reach.

Just because they are kid's bikes, why isn't it possible or useful to compare X with Y?

Is it coz kids change size quickly, and most people can't afford to keep buying them a new bike every time they grow another couple of inches?

Just glue some bits to the kid then. What I am saying is you are over complicating. The Luath 24 we bought recently just about starts to fit the kid. We bought it from somebody four years older who luckily was not a dwarf and probably had already outgrown a Luath 26. I think he did a lot of weekly mileage on the bike.

Is it coz kids change size quickly?

Zing! actually let me just quote you again.

Is it coz kids change size quickly?

Bingo.

Let put it this way, with a kids you wanna get the biggest bike they can just about fit so it'll last long enough to make your money worth, the steep seat tube and the extremely short stem allow a kids who is obviously not quite big enough to fit, can fit.

If a parents want to make the bike last a bit longer, all they have to do is shove the saddle back a bit and fit a longer stem (ahead stem on the Islabikes make light work of it).

The key selling point of the Islabikes is that they're not only very well made, but also very light and have quality components, the only downside is simply needing a little more attention to looking after it (tyres are not as thick as the tractor tyres on the Ridgeback kids bike for example).

And they're kids, they're extremely resilient, they power through and still come out with a massive grin on their face, they're not worried about having the saddle a millimetres too high, or the brake levers is a little hard to squeeze, they jump on and do their very best to abuse the bike.

I don't understand how the fact that kids grow quickly, means that comparing two bikes is irrelevant or unnecessary:

• his current bike is too big;
  
• according to Isla, both the 24 and the 26 will fit him;
  
• the 26 looks similar in size to his current bike.
  
  

Clearly the 26 would be a better buy, as he will grow out of it more slowly, but not if it is too big for him now.

If stack & reach isn't the best method of comparing two bikes, then what is?

Stop trolling.

https://www.islabikes.co.uk/sizing-advice

If stack & reach isn't the best method of comparing two bikes, then what is?

Letting your kids try it out, which I do realised not an easy feat considering Islabikes doesn't have a brick and mortar shop (Unless that have changed).

Speaking to Islabikes directly would help greatly.

They do have a brick and mortar shop, way out in the countryside, which for a townie like myself was an all day trip for an hour's chat/test ride. The restaurant/farm shop on the same site made it a lovely day out though.

It's worth the trip. Seriously.

It's worth the trip. Seriously.

I reckon it's worth it for you (if you're going there to try out bicycle for yourself that is), but the money spend on travelling make the Islabikes even more expensive to get for their childrens.

I found this calculator, which some might find useful :)

https://docs.zoho.com/sheet/published.do?rid=p2rrnf78b800f51254a4981208481abdf96a7&mode=embed#

About to purchase a new bike and need some advice on stack and reach.
Current road bike (BMC Streetracer) has Stack 57.4cm, Reach 39.5cm. Stem is slammed, and reach with a 120mm stem is ok - although I suspect I would probably be better with a 130mm stem.

Looking at a Cervelo S2/R2 - geometry is the same for both.
56cm bike gives Stack 58cm, Reach 38.7cm
58cm bike gives stack 60.5cm, Reach 39.6cm
Can I compare bikes purely on stack and reach for fit ? Looking at the numbers for the Cervelo's it appears they give a much more upright position, compared to my existing bike. To fit, I'd need a 56cm bike with at least a 130mm stem. The 58cm reach is better, but the stack is enormous.
Quite surprised, wouldn't of though the Cervelo's would be that upright.

On geo alone, the Cannondale Supersix series seems a lot better fit
56cm Stack 55.8cm, Reach 39.5cm
58cm Stack 57, Reach 39.9cm
A 58cm Supersix would seem spot on, and could go for a 56cm if I wanted a lower position.

TL;DR - Is stack & reach a good guide, and are Cervelo's really that upright a position ?

Is stack & reach a good guide, and are Cervelo's really that upright a position ?

Yes.

Yes. Because MAMILs/Dentists.

Hence why some pros have to try everything they can to get them lower, even running without a bearing cap for the headset

Thought they changed this for 2015/6 and everything became long and low again?

Cannondale a traditional fit, Cervelo a modern fit.

Thanks folks. Seems weird that Cervelo would have such an upright position, especially on the S2/3 which are billed as 'aero' bikes. I'm not looking a for flat back bar tape chewing position, but I don't want a sit up and beg position either.

Will look elsewhere. Cannondale's Supersix seem pretty spot on with sizing, so will start there.

Social Media validation is a powerful social currency for Millennials.

Because marketing.

Have you seen Trek's H2 fit? It sits in between the two.
The spectrum is 'endurance' bikes (roubaix etc) to mid-race like Trek H2, new Canyon Ultimate CF SLX and then proper race like Focus, Canyon aeroroad CF SLX etc.

Supersix sits between a Trek H2 and proper race geo.

Buy the red bike, its faster.

With stack/reach and a tool like http://bb2stem.blogspot.co.uk/ to dial in bar position you can replicate your fit across brands/frames no problem.

I have 54cm Specialized with slammed 100mm -17 stem and a 52cm Bowman with 120mm -10 stem and a small spacer and the bars are within 1mm of each other

This cyclist review of the Cervelo R2 claims "it’s all about ‘fast’ handling and riding in a low, aggressive position"
I've long suspected bike reviews to be rubbish, but did they even sit on the bike ?

http://www.cyclist.co.uk/reviews/346/cervelo-r2-review

ok... here we go again.... Which is the more useful measurement, stack or reach?

On my current bike the Reach is 410mm and the stack is 660mm. Try finding an off the peg bike with that geo!

Am I better off going for a 58cm with a reach of 412-415mm and then bumping up the stack with a few spacers or go for the biggest frame in te line up and using a shorter stem?

My current thinking is that the smaller bike with spacers gives a bit more optionality?

Which is the more useful measurement, stack or reach?

Both.

How high is your handlebar? Stack.
How far is your handlebar? Reach.

My current thinking is that the smaller bike with spacers gives a bit more optionality?

You are right. Pros do the same minus spacers of course. I actually sized up in Trek H2 geo from 52 to 54 so I could slamm ;) The reach difference was mere 2mm. Stack difference was 8mm.

The NFE you have is VERY short and tall so probably look at 'endurance' geometry.

The Stack does not include spacers, so to answer your question, reach is slightly more important as stem length can change how the bike feel.

Most bike usually come with around 25mm of spacers minimum, so a bike with a stack of 640mm would be 665mm with spacers (give or take).