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 Post subject: Bikefit
PostPosted: Mon Mar 19, 2012 8:01 am 
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Joined: Thu Feb 23, 2012 1:19 pm
Posts: 66
With my Lynskey Helix OS frame in hand, and the general issues regarding wheels (training wheels: HED-White-Sapim) and drivetrain (SRAM Red 2011/2012 and Cannondale Hollowgram SISL 170mm 34/50) and peddles (Speedplay Zero/Crankbrothers Candy) settled, I decided to take my frame in for a Bikefit.

This is after reading multiple posts and articles, incuding but not limited to Sheldon Brown's articles on bikefit and the myth of KOPS (knees over pedal spindle).

Well, since I am in Thailand, I did not find a LBS with the Retul system or anything like that.

But, I found a LBS that does the custom fitting measurements for Seven Cycles using the Juteau-Cantin (Canadian) system.

The team doing the bikefitting told me that they have been doing bikefitting for several years now...

The process started with the team (four people) measuring the geometry dimensions from the Helix OS frame and cross checking them against the geometry on the Lynskey website. They then measured the geometry dimensions from the fork (Enve 43mm rake) and handlebar (Enve compact 44 cm).

Then, they took my body measurements - height and inseam, femur, shoulder, arm, etc. etc. lengths and cross checked the measurements against the general table for meaurements table in their Juteau-Cantin book.

During this time, we talked about my riding style, typical training frequency and distance, longest rides and goals, what I liked and disliked about my current bike, what pains did I have during and after my rides, what other sports I do and have done, what injuries I had, my age, etc. etc.

They remarked that my body measurements would have dictated a Lynskey Helix OS frame in between the S and M sizes but the S would be a easier fit with other adjustments. They remarked that my shoulder bone measurements suggested a 42 cm handle bar but based on my actual shoulder physique (I swim 1.6 km three times a week), a 44 cm handle bar was appropriate. They remarked that my right knee bend seemed crooked (I had a partial ACL tear but no surgery from my skiing accident). They remarked that I was not really flexible - guilty. But, they said it is good that I had no lower back pain. Finally, they said that my legs are a bit shorter for my height compared to Europeans - typical of Asians (I was a fat kid so I did not stretch up as much as I could have - my brother is 2 inches taller than me). During this time and the interview which took almost an hour, the other members of the team assembled the mock-up bicycle.

Then, based on the Juteau-Cantin manual, they set up the bike fit mock-up bicycle with the recommended geometries and with my actual saddle (Fizik Aliante) and handlebar (Enve compact 44 cm) but with Shimano clipless peddles. They also lent me a new pair of Shimano road shoes. So, I got on the bike fit bicycle mock up.

They told me that the first issue they wanted to work on was the drive - me.

They first first explained that they believed in KOPS (knee over pedal spindle) concept because they felt that this was one of the best ways to get maximum power and smoothest down-ward stroke shape. They remarked that with my choice of a straight seat-post (no offset) they felt that my knee was too far forward. They told me that this will be one of the first test parameters.

They then asked me to peddle from the top bar position for 5 mins at a cadence of 80, with the straight seat post, a 110mm -6 degree stem, 30mm stem height from top of top tube. This was then repeated for the hood position and the drops position for another five minutes each. During this time, they asked me how I felt and took notes about my position. They had three people observing me and my peddling: one from the back, one from the side, and one from the front. After getting off, they asked me about how I felt about each position. They noted that I had earlier said that I wanted a 30 mile to 100 mile distance bike and that I wanted to stay in the drops as long as possible.

Then, they switched out the straight seat post and replaced it with a 25mm offset seat posts and repeated the test above. I had to agree that the 25mm offset seat post felt better - I felt less cramped. They noted this but told me that this was an easy modification to reverse in the future. But for now, they were staying with the 25mm offset seat post for the remainder of the fit. As for the positional feeling, I was okay with the drops, bars, and hoods.

Then, they switched out the 110mm -6 degree stem for a 120mm -6 degree stem and repeated the test above. At the end of the test, they took notes about how I felt for each position on the bicycle. This was with 30mm of stem to head tube height. I felt that the bars position was okay, the hoods position was good, but the drops position not so good.

Then, they switched out the 120mm -6 degree stem for a 100mm -6 degree stem and repeated the test above. At the end of the test, they took notes about how I felt for each position on the bicycle. This was with 30mm of stem to head tube height. I felt that the bars position was okay, the hoods was good, and the drops was good.

They said that at this point, they felt that the 100mm -6 degree stem was my choice.

But, they wanted to vary one more parameter.

With the 100mm -6 degree stem, the 25mm offset seat post, they increased the stem to head tube height first to 35mm and then 40mm. I repeated the peddling exercises and the after peddle interview.

They said that they would not recommend a stem to head tube height of more than 40mm nor would they recommend a stem length of less than 100mm nor would recommend a stem angle of less than -6 degrees. But, it was up to me.

So, we settled on 25mm seatpost offset, 100mm -6 degree stem, and 40mm stem to head tube height but with 10mm on top of the stem to spare.

But, they told me that I should ride more and do yoga to increase my flexibility so I can slam my stem down to the head tube in the future. They told me that it would take about 3 years and 10,000 km a year to get me there. They invited me to come back every six months.

This whole process took 3 hours and cost me 30 USD!

Comments?

With Regards,

Mark

_________________
2012 Lynskey R330 with SRAM Red Quarq
2013 Parlee Z1 with DA 9070
2013 Lynskey Helix OS II with SRAM Red


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 Post subject: Bikefit
Posted: Mon Mar 19, 2012 8:01 am 


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 Post subject: Re: Bikefit
PostPosted: Mon Mar 19, 2012 1:26 pm 
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Joined: Fri Jan 27, 2006 1:38 pm
Posts: 568
Location: Greater Pittsburgh
A few things that I would comment on... I kind of find it weird that they started with taking geometric measurements from the frame first... normally, a bike fit start with an interview, so the fitter can understand your background, previous/current injuries/issues, current fitness level, goals, type of racing/riding, terrain, etc. etc. Basically, understand you as a cyclist. After that, you start with body measurements, flexibility, core strength. Only after all that do you start with the current frame (or new fit on a fit bike). The reason why you go in this order is for the fitter to place you first and foremost and not the frame/geometry.

Second, although KOPS may not be scientific, at least it start with the bike fit in the right location, that is the relationship to you over the bottom bracket. Everything else will build from this point on.

Most important comment that leads me to think this is a serious fitter, they asked you to ride for a while and then come back for a follow up. No one can get the fit perfect the first time and serious fitters will ask you to get back to them with comments/questions/concerns and will adjust the fit accordingly. This is one of the reasons why a fit does cost a bit of money...

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"Suddenly the thought struck me; my floor is someone elses ceiling" - Nils Ferlin


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