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PostPosted: Mon May 07, 2012 6:46 pm 
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Hi all, I've enjoyed my Lynskey r230 well enough for the past year, but despite two professional fits can't shake the horrible lower back pain after 40 or so miles.

My last fit, we determined I was not stretched out enough. Too hunched up, and thus the lower back pain. We tried a longer stem by 2cm and increased seatpost setback from 16mm to 25mm. It helped some, but not enough.

I decided to try some other bikes out at this same shop. Rode two different size Orcas and a Colnago EPS. The colnago blew me away with how it rode, but I'm not sure if fit wise is was perfect. It was a 55cm not sloping. My Lynskey is a size M 54.1cm top tube.

Seeing that the C59 in size 52s has 73.5 seat tube angle vs 74 on the EPS, I think it may fit better than the EPS. When getting fitted I had a tendency to ride on the back of the saddle searching for more room. The Lynskey is also 73.5 but with the shorter top tube.

So I ordered a C59. But now, after waiting a month, am going over the geometry again. Most every big name bike I see has a 73.5 seat tube angle. Then I saw the BH Ultralight at 72.5. Hmm, would that give me more room?

I know, too hard to give this kind of advice online. But if anyone has opinions on the C59, the bh ultralight (hard to find much discussion on this one) or a nice guide to help me understand geometry, I'd appreciate it. Or if you have a story or experience either figuring out geometry that worked for you or getting on something that really did NOT work for you, please share!

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Posted: Mon May 07, 2012 6:46 pm 


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PostPosted: Mon May 07, 2012 9:08 pm 
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Location: Cambridge, New Zealand
Plenty of us can help you understand geometry. But IMO discussing that is putting the cart before the horse for you. First you need to know what your correct position is, then order a new bike to suit.

That might mean buying a Zoom 40mm offset (a heavy alloy model) post to allow more room for playing with setback. It definitely means finding a better fitter or self educating about fit.

As a fitter - it's very frustrating when people come in having just bought a bike that is the wrong size and limiting in achieving the correct position. Some people will live with the compromises and others take the hit of selling a couple of week old bike and getting something that works for them. Much better to get it right by choosing a bike to match a known position.

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PostPosted: Mon May 07, 2012 9:40 pm 
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still at kops? how much bar drop?

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PostPosted: Mon May 07, 2012 9:46 pm 
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Location: Atlanta, GA, US
What the seat tube angle (STA) dictates is what kind of seatpost (i.e., how much setback) you will need to achieve a given saddle position in relationship to the BB. A good rule of thumb is that for each 0.5 degree of slacker STA, your reach decreases by about 5 mm, all else being equal. For instance, a frame with a 72.5 degree STA and a 57cm top tube will have a 10mm shorter reach compared to a frame with a 73.5 degree STA, again all else being equal.

The goal of a good fit in my opinion is to achieve the right saddle to BB position first, then dial everything else in from there. With that said, you can get different bikes with different STAs to fit the same given the various seatposts available with different setbacks (assuming you are not using a proprietary ISP system, where your options may be more limited) and various stems available in all kinds of rise and length.

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PostPosted: Tue May 08, 2012 12:07 am 
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Location: Gold Coast, QLD, Australia
fa63 wrote:
The goal of a good fit in my opinion is to achieve the right saddle to BB position first, then dial everything else in from there. With that said, you can get different bikes with different STAs to fit the same given the various seatposts available with different setbacks (assuming you are not using a proprietary ISP system, where your options may be more limited) and various stems available in all kinds of rise and length.


Agree, I always cringe when I see people on here recommending changes in saddle setback to achieve accurate reach requirements.

Then again, I cringe when anyone asks for fit advice

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PostPosted: Tue May 08, 2012 1:26 am 
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Murphs wrote:
Then again, I cringe when anyone asks for fit advice


I know, I've read plenty of worthless posts similar to what I just posted. So if anybody wants to gloss over my personal issues here and just share their own experiences in getting their fit dialed in (and more specifics on geometry the better), that's great.

More on me - I've had a Retul fit on my bike. Felt okay before, felt okay afterwards - the only thing we changed was the stem from 100mm -6 degrees to 100mm -18 degrees. Looking back, I still had maybe 25mm of spacers below the stem, so I'm not sure why we'd go lower on the angle. Problem is and has been the same with me - too much pressure on the hands (which I can deal with, just know it's a problem with my fit) and eventually on longer rides lower back pain. Painful lower back pain that impedes my cycling, and disappears off the bike.

I'm 30, 5' 10". Fairly flexible, can get touch the second knuckle to the ground when "touching my toes". Stretch 3 to 5 times a week, in addition to after exercise. I'm 145 pounds, but I do lift weights regularly. My abdomen and back should be okay - I do exercises with weights for both.

cyclenutnz wrote:
Plenty of us can help you understand geometry. But IMO discussing that is putting the cart before the horse for you. First you need to know what your correct position is, then order a new bike to suit.


Interesting...sounds like hooking up with that magical, hard to find fitter who has a wealth of knowledge and the time or desire to use it is what you're advocating. To you, is finding the correct position more than just the sum of my measurements + flexibility?

adriano wrote:
still at kops? how much bar drop?


I haven't had someone measure KOPS in forever, and trying it myself is proving...difficult. I was fit via Retul on a 16mm setback post, and am riding a borrowed 25mm setback post now. The 16mm post is what came with the bike. Saddle to bar drop is 2.5" currently. I've been playing with it and moving the bars lower, which is feeling better.


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PostPosted: Tue May 08, 2012 2:03 am 
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fa63 wrote:
What the seat tube angle (STA) dictates is what kind of seatpost (i.e., how much setback) you will need to achieve a given saddle position in relationship to the BB. A good rule of thumb is that for each 0.5 degree of slacker STA, your reach decreases by about 5 mm, all else being equal. For instance, a frame with a 72.5 degree STA and a 57cm top tube will have a 10mm shorter reach compared to a frame with a 73.5 degree STA, again all else being equal.

The goal of a good fit in my opinion is to achieve the right saddle to BB position first, then dial everything else in from there. With that said, you can get different bikes with different STAs to fit the same given the various seatposts available with different setbacks (assuming you are not using a proprietary ISP system, where your options may be more limited) and various stems available in all kinds of rise and length.


Thanks for this, very interesting. I'll display my ignorance here - I had thought that a slacker seat tube angle would extend reach. Which had me confused when the BH with the 72.5 angle had a shorter reach than similar sized bikes with slightly shorter top tubes. Makes sense now, but I'm still picturing a slacker angle as moving the seat away from the bars...

After reading your post, I'm thinking there's not much to varying seat post angles between bikes, especially if you stay at what I see as the more common 73.5 (in size 54 to 56 range).

I made a spreadsheet of different bikes and their geometry's, and if I'm looking at my size range, it's hard to really see a difference. I've been told that my 54 Lynskey is too small, based on my feedback over 5 different fit sessions. Each session we talk, I ride the bike on the trainer, we may ride a bit outside together and then we'll make an adjustment. After that, I ride a longer ride on the weekend, and rinse/repeat. I did 5 sessions over 5 weeks, and still have my shop's parts on my bike.

Going up to a '56' seems to net me about 1.5cm in top tube length, 1 to 1.5cm in head tube length, and...well, the angles are about the same. Colnago doesn't publish a HT angle, and without the fork rake that most sites aren't listing, I'm not sure what it really tells me. Am I going down the wrong track thinking that with the use of stems, spacers, seat posts and bars, there's not much difference between most mainstream models? Are the mega-mart bike stores right?

Quote:
"How tall are you? 5' 10? Size X here is the one for you!"


What sold me on the Colnago was the feel - the EPS I rode was incredible. The Orbea Orca Gold with Super Record was meh, anything it had going for it was wasted on me. It felt like my Lysnkey under my butt in terms of feel. The Colnago was soooo smooth, it was amazing. Similar clinchers with same pressure.

Meh, I just want to be comfortable on my bike. It sucks having to pack it in because of pain unrelated to physical exertion.


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PostPosted: Tue May 08, 2012 3:05 am 
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Location: Atlanta, GA, US
The effect of STA and its implications on reach can be difficult to visualize for some. What helped me back in the day was to play around in AutoCAD, until I ran into BikeCad (www.bikecad.ca). You can go on there (the basic version is free) and enter the numbers for your existing frame (or a new one), and see how changing things around like the STA and HTA impact the geometry.

Good luck.

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Last edited by fa63 on Tue May 08, 2012 3:33 am, edited 2 times in total.

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PostPosted: Tue May 08, 2012 3:24 am 
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Location: Sydney
this is also a great tool for comparing the geometry of different bikes courtesy another forum member:

http://bb2stem.blogspot.com.au/

Just click to edit and enter values into the spreadsheet.

Not sure where you're based but if in australia/sydney, steve hogg is a fitter I have had good experience with- he's been great in recommending frames to suit my unusual dimensions as well as getting my other bikes fit.

As for colnago, unfortunately they dont publish enough info on geometry to really work out whether a specific size will work for you (no bb-drop, no fork length, no HTA, making stack and reach a bit tricky to calculate). Though given there are quite a few here with first hand c59 experience, they can probably give some better info on STA its effect.


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PostPosted: Tue May 08, 2012 8:21 am 
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Joined: Mon Mar 07, 2011 10:00 am
Posts: 176
Location: Melbourne
jasoncd wrote:
Thanks for this, very interesting. I'll display my ignorance here - I had thought that a slacker seat tube angle would extend reach. Which had me confused when the BH with the 72.5 angle had a shorter reach than similar sized bikes with slightly shorter top tubes. Makes sense now, but I'm still picturing a slacker angle as moving the seat away from the bars...

Hi you have your terminology a bit wrong, hence the confusion
Reach is not from the saddle to the bars, which is what you are describing - it is a function of the frame, not the accessories!
Reach doesn't need to extend with a slacker seat tube, it depends on the pivot point, if you lengthened the stays the reach could stay the same but the wheel ase can get out of control if you go to far!


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Posted: Tue May 08, 2012 8:21 am 


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PostPosted: Tue May 08, 2012 11:01 am 
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Frame reach is measured horizontally from the centre of the BB to the top centre of the head set.

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