Understanding the foibles of reach....

[diegogarcia]

Question for the geo experts here.

I note of late, on here and on other bike forums, there are a few examples where people are changing a frame and looking at the geo and before buying finding that the reach is similar. However, a few people have posted that when they set the bikes up, the reach seems longer than expected. If you look here for example -

viewtopic.php?f=10&t=66856&start=660

But, what is causing this. Are we missing something ? Is the STA or HTA playing a part, BB height, or simply Giants as one brand, have 'unique' geo for example. I went from a Tarmac 56 which I felt fitted like a glove, yet since buying a M/L TCR I find it slightly long, so I have gone down to a 90mm stem for the first time in my life. When I looked at a 56 Tarmac compared to a M/L TCR they seemed so inherently the same but different - ergo a 0.5cm longer top tube offset by a 1cm taller head tube and so on. The reach as someone said is the difference between gloves or no gloves ! The reach is Tarmac 39.5 over the TCR at 39.8 - a 0.3 difference.

So what gives ? Why are some bikes simply feeling bigger ? What are people forgetting ? The only thing I can attribute it to is STA but then I am not sure.

Thanks in advance.

Diego.

[benzebub]

Als I understand, reach is measured from the middel of the BB, so everything behind the BB isn't included in measurements. Like you said, if the Seat tube angle is different, this will affect the effective reach of the bike.

[diegogarcia]

Als I understand, reach is measured from the middel of the BB, so everything behind the BB isn't included in measurements. Like you said, if the Seat tube angle is different, this will affect the effective reach of the bike.

OK yes, so the line often drawn into geo images from centre of the BB is where reach starts from. So if I rider jumps off a steep STA then onto a slack STA then there will be a difference. Obviously you triangulate the contact points to mirror, but this is why some bikes simply feel bigger ? Having short legs than my height suggests not ideal really but I am not alone in that.

[mattr]

HTA plays a small part. A steeper one will move the bars slightly further away from you and slightly down if you use the same stem/spacers/bar. If you use a lot of spacers the effect on reach will be amplified.

STA should make no difference at all.
The saddle position should be measured from the bottom bracket centre. If you have a difference there, you haven't mirrored the position.

[corky]

Oh no.....someone mentioned using a 90mm stem........

This one's gonna explode........

Fit starts with cleat position........

[diegogarcia]

Oh no.....someone mentioned using a 90mm stem........

This one's gonna explode........

Fit starts with cleat position........

LOL - yes but I negated it by adding 10mm of reach to my bars so I look like Peter Sagan

[corky]

Oh no.....someone mentioned using a 90mm stem........

This one's gonna explode........

Fit starts with cleat position........

LOL - yes but I negated it by adding 10mm of reach to my bars so I look like Peter Sagan

So either you're cool to 'fess up or you're an Agent Provocateur....

Seriously though, reach should be determined after you are sitting in the correct position......

[TheDarkInstall]

As I am now employed by Canyon as their official stem length consultant, I can reveal the new set up they have been working on, following my strict instructions.

This should sort out any reach issues people were having.

[wingguy]

So what gives ? Why are some bikes simply feeling bigger ? What are people forgetting ? The only thing I can attribute it to is STA but then I am not sure.

The STA shouldn't affect things at all as long as you have set your saddle up so that your hips are in the same place relative to the BB.

If you were running an extra 1cm spacer on the Tarmac then that adds about 2mm to the effective reach of the Giant, but obviously this is still neglible.

What about the front of the bike? Have you checked the bar + STI reach between both bikes? This can be radically different between steups (potentially a few cms!) but you wont find it marked on any geo chart.

[icenutter]

Mountain bikes have moved towards shorter stems and longer top tubes. The theory goes that you get more stability for the same reach (using the word reach loosely here).

[wingguy]

Part of that is compensating for using wider bars, most of it is about pushing the front wheel as far forwards as possible for steep downhill handling.

The only drop-bar bike I've seen try the same thing is the new Whyte gravel frame, the Friston and Gisburn. The 54cm has a reach of 415mm - that's a few mm either side of 4cm longer than bikes like the SuperX, Grade, Norco Search etc. Will be interesting to see how it works.

[diegogarcia]

So here is a question then.

Take a Cervelo R3 frame. 56cm. 564 top tube. 173mm head tube, 3mm taller than a TCR M/L 2014/15. Yet, the reach is 387 from 389. Why ? Is it the .5 a degree of seat tube steepness ?

Thanks.

[Denavelo]

I recently realized my issue was with the brands that make handlebars.
According to FWB, there is no standard on measuring handlebar reach from an industry perspective. I bought a pair of Zipp SLTB bars with an advertised reach of 92mm, but actual was 102mm. That's like going from a 110mm stem to a 120mm stem, just in bar reach. I went to a bar (New ultimate Evo) that tested actual and advertised (85mm reach), and oh my! What a world of difference. I think handlebars are the main culprit with fit that no one addresses, not even the bike industry. They should make a standard on calculating reach, across all brands.

http://blog.fairwheelbikes.com/reviews-and-testing/road-handlebar-review/

From the review regarding reach....

Notes about reach, drop and flare: One thing that has always bothered us is that there is no standard system for measuring reach and drop. Actual vs. claimed reach particularly can vary dramatically, in this test alone the bars range by almost 3 cm in Reach. 3cm can be the difference between needing a 9 cm or 12 cm stem, yet many people don’t consider reach on their bars when making a choice.

[Denavelo]

.

[wingguy]

So here is a question then.

Take a Cervelo R3 frame. 56cm. 564 top tube. 173mm head tube, 3mm taller than a TCR M/L 2014/15. Yet, the reach is 387 from 389. Why ? Is it the .5 a degree of seat tube steepness ?

Sorry, what is the question?