General Discussion Triathlon Talk » Bike Fit... sweet spot or ever evolving? Rss Feed  
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2013-10-10 10:43 AM
in reply to: Donto

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Subject: RE: Bike Fit... sweet spot or ever evolving?
Question:

I just noticed that I have Michelin Ultra Light tubes not the latex, could I use those instead of latex and get the same benefits?

and I noticed that the presta valve is not removable, what kind of valve stem extender for nonremovable valves?



2013-10-10 11:05 AM
in reply to: tomspharmacy

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Subject: RE: Bike Fit... sweet spot or ever evolving?
Originally posted by tomspharmacy

Question:

I just noticed that I have Michelin Ultra Light tubes not the latex, could I use those instead of latex and get the same benefits? and I noticed that the presta valve is not removable, what kind of valve stem extender for nonremovable valves?




No, butyl won't give you the same benefits as latex, even if the butyl is an 'ultralight' tube. For valve extenders, I like zipp extenders put on correctly (so valve locked open, use plumbers teflon tape, make sure it is tight), they work very well on most any good tubes.


Greg @ dsw
2013-10-10 12:14 PM
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Edited by Fred D 2013-10-10 12:17 PM
2013-10-10 12:48 PM
in reply to: Fred D

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Subject: RE: Bike Fit... sweet spot or ever evolving?
Thought I'd share a pic of my 15 year old's position in the event someone sees something obvious that I am missing as far as position/fit.  Sorry for the less than stellar quality.



(gposition.png)



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2013-10-10 12:52 PM
in reply to: Left Brain

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Subject: RE: Bike Fit... sweet spot or ever evolving?
overall looks pretty good. Tell him to move his Wingspan "up" his forehead a bit... it'll fit a little tighter to his back.

Can't really tell from the pic... seat may be a couple mm high.
2013-10-10 2:21 PM
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Subject: RE: Bike Fit... sweet spot or ever evolving?
Originally posted by Left Brain

Thought I'd share a pic of my 15 year old's position in the event someone sees something obvious that I am missing as far as position/fit.  Sorry for the less than stellar quality.


LB,

Looks pretty good, I put lines on the pic, he's right at 90 degrees... flat back. His right leg at TDC looks like it's not too high. No wonder he's fast, young, flexible and good fit. I wouldn't recommend going lower. I put in a pic of Fabian too for comparison. Lego is right, the helmet could be cantered back on his head a bit for smoother flow.

Maybe during the off season, you guys could experiment with tilting the extensions up, clothing like the new Casteli top for triathlon and testing things like that.

Edited by tomspharmacy 2013-10-10 2:33 PM




(000622fa-642.jpg)



(gposition.png)



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2013-10-10 2:36 PM
in reply to: tomspharmacy

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Subject: RE: Bike Fit... sweet spot or ever evolving?

Cool....thanks Lee and Tom.  The helmet was borrowed and we are in the procdess of testing some others.  We did the fit on our own working with some formulas from Competitive cyclist and what I've picked up here in the last few years and some other web sites. 

And then.....every time I came home from work he had dropped his bars some more, or moved his seat around just trying to find what really felt good to him.  What you see there is mostly the result of him moving things, then testing them, then moving them....kind of what Leego has been doing.  Once he got here it was, "hey dad, I think I got it........this is fast!!" Laughing

2013-10-10 3:07 PM
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Subject: RE: Bike Fit... sweet spot or ever evolving?
Ok, to the latex tube guys,

I have only found a local LBS, trek dealer, that has Bontranger XXX latex. I can get MIchelin or others over internet but would recieve them until next week. I want to testa and install this weekend. Any comments on Bontranger?



Edited by tomspharmacy 2013-10-10 3:07 PM
2013-10-10 3:32 PM
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Subject: RE: Bike Fit... sweet spot or ever evolving?

Originally posted by tomspharmacy Ok, to the latex tube guys, I have only found a local LBS, trek dealer, that has Bontranger XXX latex. I can get MIchelin or others over internet but would recieve them until next week. I want to testa and install this weekend. Any comments on Bontranger?
I've gone to using the Bontranger XXX latex tube too as two of the LBS's are carrying  them now. The Mich latex tubes are harder to come by and there were some good bidding wars on eBay for them last time I was looking at them. IIRC, older BTR data showed all the latex tubes tested to be fairly comparable.



Edited by Donto 2013-10-10 3:32 PM
2013-10-10 5:50 PM
in reply to: tomspharmacy

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Subject: RE: Bike Fit... sweet spot or ever evolving?
Originally posted by tomspharmacy

Ok, to the latex tube guys,

I have only found a local LBS, trek dealer, that has Bontranger XXX latex. I can get MIchelin or others over internet but would recieve them until next week. I want to testa and install this weekend. Any comments on Bontranger?




I have been using Bontrager for a few years now. No issues with them. They have removable cores and Bontrager also makes extensions.
2013-10-10 11:43 PM
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Subject: RE: Bike Fit... sweet spot or ever evolving?

Tom, leego, et al....we were looking at the lines Tom made tonight and he said, "If I get lower in the front I'll have to look up more and my helmet will get closer to my back, I can do that".  What do you think? He's REALLY comfortable in the shown position. We talked about how his angles will change but we don't know how that will affect performance/power.  Is it worth a try? What other measurements would we have to change to keep him at 90 degrees if he lowered?  The kid has a natural aptitude for this, but no idea about the "science" behind it.  For my part.....I'm at the very edge of where I can help him without advice.  Thanks.



Edited by Left Brain 2013-10-11 12:01 AM


2013-10-11 3:44 AM
in reply to: Left Brain

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Subject: RE: Bike Fit... sweet spot or ever evolving?
Originally posted by Left Brain

Tom, leego, et al....we were looking at the lines Tom made tonight and he said, "If I get lower in the front I'll have to look up more and my helmet will get closer to my back, I can do that".  What do you think? He's REALLY comfortable in the shown position. We talked about how his angles will change but we don't know how that will affect performance/power.  Is it worth a try? What other measurements would we have to change to keep him at 90 degrees if he lowered?  The kid has a natural aptitude for this, but no idea about the "science" behind it.  For my part.....I'm at the very edge of where I can help him without advice.  Thanks.




If he moves his seat forward, his pads forward and down he will preserve the same angles

He will in fact rotate around the BB. But at one point it may become too forward/steep.

For every 1.6cm forward, pads go 1cm down and 1 cm forward (approximately).
2013-10-11 4:05 AM
in reply to: marcag

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Subject: RE: Bike Fit... sweet spot or ever evolving?
mainly what Marc said other than... I wouldn't move his pads forward to start with. I think he's got room there to leave it alone.

Mark what you've got right now first, that way you can go back.
2013-10-11 4:11 AM
in reply to: Leegoocrap

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Subject: RE: Bike Fit... sweet spot or ever evolving?
After a couple hours of work finding that "sweet spot"





(p3position.jpg)



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2013-10-11 8:00 AM
in reply to: Leegoocrap

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Subject: RE: Bike Fit... sweet spot or ever evolving?
Originally posted by Leegoocrap

After a couple hours of work finding that "sweet spot"




How long is that stem ?
2013-10-11 8:04 AM
in reply to: marcag

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Subject: RE: Bike Fit... sweet spot or ever evolving?
120, had to be a bit longer than my usual 90-100 to get a little more reach. The 100ks are a little short. (and not terribly adjustable in that respect)


2013-10-11 9:48 AM
in reply to: Left Brain

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Subject: RE: Bike Fit... sweet spot or ever evolving?
Originally posted by Left Brain

Tom, leego, et al....we were looking at the lines Tom made tonight and he said, "If I get lower in the front I'll have to look up more and my helmet will get closer to my back, I can do that".  What do you think? He's REALLY comfortable in the shown position. We talked about how his angles will change but we don't know how that will affect performance/power.  Is it worth a try? What other measurements would we have to change to keep him at 90 degrees if he lowered?  The kid has a natural aptitude for this, but no idea about the "science" behind it.  For my part.....I'm at the very edge of where I can help him without advice.  Thanks.




Exactly what marcq said, but I'll add that you'll also be moving his knee forward too, farther beyond the center of the pedal, when you move forward. Then could possibly cause changes in knee pressure and may cause an injury.
2013-10-16 10:37 AM
in reply to: tomspharmacy

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Subject: RE: Bike Fit... sweet spot or ever evolving?
btw... to be fair to everyone (and admit when I'm wrong) I have been riding the cervelo (with the above, higher position) and it is more powerful.

Now just to be sure it's FASTER

(and...hopefully be able to stop/turn safely)
2013-10-17 2:37 PM
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Subject: RE: Bike Fit... sweet spot or ever evolving?
Originally posted by Leegoocrap

btw... to be fair to everyone (and admit when I'm wrong) I have been riding the cervelo (with the above, higher position) and it is more powerful.

Now just to be sure it's FASTER

(and...hopefully be able to stop/turn safely)


Cool, do you plan to run this setup in the future? It'll be interesting to get a real world follow up.


As for the GP4000s / Bontrager Latex combo... got them installed and ran a few rides and some spots over rough ripple roads... I was doing 23 to 27 over them and bouncy, but no issues... Phew... takes a worry off my mind.

I adjusted slightly downward my extensions angle do to discomfort at the higher angle... I didn't feel that I would like the higher position for 56 miles, on my shoulders and back. I feel more relaxed with the slightly lower angle.

I did some new coast downs and cal rides for the power meter after the position adjustment and tires. It recorded a lower crr by 25 to 30%. I measured the rollout too, the contis are 22mm longer rollout... so if I keep the same gear and cadence, that extra inch will make the speed faster all by itself... and consequently... the cal ride showed a slightly improved CDA too... huh? from the arms?

I'll give a follow up after the race.

Edited by tomspharmacy 2013-10-17 2:41 PM
2013-12-13 7:35 AM
in reply to: tomspharmacy

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Subject: RE: Bike Fit... sweet spot or ever evolving?
So, a couple of months have passed, anyone else trying new things?

This is where I'm at right now... pretty happy with it, but not totally (front hydration is going to be a PITA due to the w-bend bars)





(kask.jpg)



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2013-12-13 10:32 AM
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Subject: RE: Bike Fit... sweet spot or ever evolving?
Chris, I know it the angle of the camara, but man you look low, have you ever used a genomometer on your position points? I know you mentioned about 155mm cranks, that would probably go a long way to making you look comfortable at TDC, at least that would make me more happy.


I don't have pictures to put on:

Something that I've recently realized is that I have long legs to torso height, and long arms, so it limits some stuff, such as saddle-pad drop

My old measurements pre Dec. 2013 (170mm crank arms, 75mm BB-saddle)

BB-torso angle: 99 degrees
Max knee angle BDC: 144 (1st most important)
Min knee angle TDC: 80
Min knee angle- torso angle (2nd most important): 42 - see NOTE below
Seat to aeropad drop: 97.5mm - 3.8 inches
Aeropad width: 190mm - 19cm

New measurements (165mm crank arms, raised saddle 8mm:

BB-torso angle: 95
Max knee angle BDC: 148
Min knee angle TDC: 85
Min knee angle-torso angle: 45
Seat-aeropad drop: 108mm - 4.25 inches
Aeropad width: 160mm - 16cm

NOTE: From this new position, I've gotten a little flatter and gained 1.5 cm of hip space at TDC, my functional range of motion is improved since I don't have to strain the hip flexors as much at TDC... I've noticed that I have some limited flexibility at BDC, which keeps my max knee angle just under 150 degrees. I personally believe that the knee-torso angle at TDC is one of the most improtant numbers for triathletes, it affects power and range of movement over the dead spot near TDC. Example, try this exercise, put dumbells in hand and squat down so your knees are past 45 degrees, then squat up, as you move up in weight, you will no longer be able to lift weight since the hip flexors are required to do more work and are a very small muscle group, but if you limited motion to 45 degrees and squat up, you employ some hip flexors, but ALL of the quads/buttocks are used and the hip flexors won't tire as quickly or fail over the length of the bike leg... an athlete will then have less fatigue and more range of motion for the run.

I haven't tested my new position on the open road, been a little cold for Arizona, and replacing the chain, waiting for new chain, but update in near future.

Edited by tomspharmacy 2013-12-13 10:36 AM


2013-12-13 4:28 PM
in reply to: tomspharmacy

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Subject: RE: Bike Fit... sweet spot or ever evolving?
Originally posted by tomspharmacy

Chris, I know it the angle of the camara, but man you look low, have you ever used a genomometer on your position points? I know you mentioned about 155mm cranks, that would probably go a long way to making you look comfortable at TDC, at least that would make me more happy.



Well going to shorter cranks would actually make me lower.

It's probably the highest I've ever been on a TT bike.
2013-12-13 11:15 PM
in reply to: Leegoocrap

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Subject: RE: Bike Fit... sweet spot or ever evolving?
You r right about needing to go higher, so your seat post will be even higher, have you thought of going to the next frame size up? Your current one seems to be on the border too small.
2013-12-13 11:44 PM
in reply to: tomspharmacy

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Subject: RE: Bike Fit... sweet spot or ever evolving?
depends. Cervelo's are too long in larger sizes, and of course we're assuming I want to be higher, which I don't think I do.
2013-12-14 12:11 AM
in reply to: Leegoocrap

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Subject: RE: Bike Fit... sweet spot or ever evolving?

Lee, in the last pic you posted your hip angle looks too pinched.....I'd be curious to know what your power looks like compared to your position when you were a bit higher.  I agree that aero is king.....but at some point I think you get to the point where power vs. aero becomes an issue.  You look close in that last picture, and maybe past the point of diminishing return?  Just my thoughts from looking at it.

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