Advice required regarding a geometry question.

Discuss light weight issues concerning road bikes & parts.
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diegogarcia
Posts: 470
Joined: Sat Apr 24, 2010 7:31 pm

by diegogarcia

Hi all,

Can anyone advise on something I may be missing ?

I currently run two bikes -

https://www.giant-bicycles.com/gb/2014- ... -sl-3-2014

and

https://www.specialized.com/gb/gb/langster/106256

I use my 56cm Langster to commute / train on. To me, it feels and fits like a glove. Paradoxically, I get on my M/L TCR for the best days and it feels huge. The top tube is longer on the TCR at 57 with a 39.8 reach but the reach is a touch longer on the langster at 40.3 yet it feels hugely smaller / a better fit reach wise and I am not reaching as far - same handle bars and stem though Langster steeper head tube. Can anyone say what is causing this to feel like this. Both have the same bike fit distance from saddle to bars and I am completely flummoxed as to how they feel like they do. The only caveat I can think of is the steep seat tube angle on the langster has something to do with it...?!?! Or is it simply top tube as the langster 55.7 from 57 - though I cant see how a shorter top tube has longer reach....!!!!!! :smartass: :noidea: :roll: :D

Any ideas? I seem to be missing the basics here as always thought a longer reach just that !!!

Thanks.

by Weenie


liam7020
Posts: 817
Joined: Tue Jul 27, 2010 10:04 am

by liam7020

No expert but the Langster has considerably steeper head and seat tube angles compared to the Giant. Also is your saddle fore and aft the same on both bikes? And the angle of your stem plus the reach and drop of your bars could also be contributing factors. Just a few thoughts.
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Marin
Posts: 2818
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

How about taking a tape measure to your seat & levers?

wingguy
Posts: 3960
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

diegogarcia wrote:I use my 56cm Langster to commute / train on. To me, it feels and fits like a glove. Paradoxically, I get on my M/L TCR for the best days and it feels huge. The top tube is longer on the TCR at 57 with a 39.8 reach but the reach is a touch longer on the langster at 40.3 yet it feels hugely smaller / a better fit reach wise and I am not reaching as far - same handle bars and stem though Langster steeper head tube. Can anyone say what is causing this to feel like this. Both have the same bike fit distance from saddle to bars and I am completely flummoxed as to how they feel like they do. The only caveat I can think of is the steep seat tube angle on the langster has something to do with it...?!?! Or is it simply top tube as the langster 55.7 from 57 - though I cant see how a shorter top tube has longer reach....!!!!!! :smartass: :noidea: :roll: :D

The top tube is shorter because the seat tube is steeper. Reach measures from the BB so seat tube angle does not affect it.

One thing I see is that you're fixating on reach when there's also a 3cm stack difference between the bikes, potentially a quite different saddle position and one of them has STIs while the other is a fixie.

First, compare the saddle setbacks to find out whether your arse is in the same place. Then find out how different the drop is on each bike (if the TCR is set up 3cm higher than the Langster then it will obviously feel huge!). Then look at where you are actually resting your hands on each bike. If your default position on the TCR is resting on the hoods then it will be significantly longer than any position available on the Langster unless you've put hoods of the same length onto it.

Valbrona
Posts: 1488
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

Giants have about the longest reach of any race-orientated bike.

kulivontot
Posts: 1170
Joined: Sun May 16, 2010 7:28 pm

by kulivontot

I think the rule of thumb is 1cm of additional reach per degree of seat tube angle. As others have stated, measure seat - bb position and then bb to handlebar position.

wingguy
Posts: 3960
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

Valbrona wrote:Giants have about the longest reach of any race-orientated bike.

Umm, nope. In the smaller sizes they're actually short reach tall stack compared to most, in the middle sizes they're bang on average, and only in the biggest sizes are they a touch longer than most.

by Weenie


diegogarcia
Posts: 470
Joined: Sat Apr 24, 2010 7:31 pm

by diegogarcia

Thanks all, I will do some measuring later. Off to work on the Langster now. Much appreciated.

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