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-   -   Racer Tech Thread (https://www.bikeforums.net/33-road-bike-racing/956936-racer-tech-thread.html)

Ygduf 05-05-15 07:40 PM


Originally Posted by tetonrider (Post 17779956)
well, on all our bikes the stays are a bit flexible, so in theory you could add a couple washers and still jam a wheel in there.

I guess you could, but that would change the angle of the stay at the hub, right? I dunno. It's weird and if this turns out to be some weird old hub that saves 2w at 30mph but is 2mm narrower than standard, that's pretty negligent to keep putting it back on the kid's bike.

wens 05-05-15 07:51 PM

I mean, I want to see somebody draw a free body diagram of how a wheel gets driven out. Maybe cocked enough to brake rub/rub the chainstay, but I've never even heard of a rear wheel falling out from sprinting before this thread.

To my original point, the forces in the wheel should be pulling it up into the drop out. It's not like we're talking track wheels that can move in the same direction as the force from the chain.

hack 05-05-15 08:02 PM

I can't really say how it happened to me, but it did. It was right after a hard jump for a 200m sprint. First two pedal strokes were solid then the rear just felt wobbly and soft. I coasted until the others riders came past and checked it out. The rear skewer was really loose (even though it had been tightened that morning) and the wheel was kind of just floating in the drop out. I cinched it down to what felt like normal, check it periodically, but haven't had an issue since. Maybe something happened earlier in the day or the quick release got hit and I didn't know it ... dunno, but it wasn't a fun experience.

Ygduf 05-05-15 08:04 PM


Originally Posted by wens (Post 17780033)
I mean, I want to see somebody draw a free body diagram of how a wheel gets driven out. Maybe cocked enough to brake rub/rub the chainstay, but I've never even heard of a rear wheel falling out from sprinting before this thread.

To my original point, the forces in the wheel should be pulling it up into the drop out. It's not like we're talking track wheels that can move in the same direction as the force from the chain.

it's the crazy junior sprint where the bike swings 60 degrees in an arc, side to side. As the rider weights the left foot, the juniors bike is 30 degrees tilted to the right. That creates a fulcrum of down force on the left side of the hub, and the tire provides a sideways resistance that causes the right side of the hub to pop out, especially if it's some non-normal hub or the skewer is loose.

spectastic 05-05-15 08:06 PM


Originally Posted by wens (Post 17780033)
I mean, I want to see somebody draw a free body diagram of how a wheel gets driven out. Maybe cocked enough to brake rub/rub the chainstay, but I've never even heard of a rear wheel falling out from sprinting before this thread.

To my original point, the forces in the wheel should be pulling it up into the drop out. It's not like we're talking track wheels that can move in the same direction as the force from the chain.

you don't need a diagram. just loosen the skewer, lift the wheel, turn the crank, and watch that sucker jump out.

tetonrider 05-05-15 08:15 PM


Originally Posted by Ygduf (Post 17779991)
I guess you could, but that would change the angle of the stay at the hub, right? I dunno. It's weird and if this turns out to be some weird old hub that saves 2w at 30mph but is 2mm narrower than standard, that's pretty negligent to keep putting it back on the kid's bike.

it wouldn't change the angle in any material way. you're basically making it 1mm or so wider--chainstays are >400mm.

anyway, it is weird to *need* to do it.

i'm confused by this whole thread, but i thought this was some weightweenie hub from when his kid was 70 pounds???

agreed on negligence suspicion.

Ygduf 05-05-15 08:17 PM


Originally Posted by hack (Post 17780064)
I can't really say how it happened to me, but it did. It was right after a hard jump for a 200m sprint. First two pedal strokes were solid then the rear just felt wobbly and soft. I coasted until the others riders came past and checked it out. The rear skewer was really loose (even though it had been tightened that morning) and the wheel was kind of just floating in the drop out. I cinched it down to what felt like normal, check it periodically, but haven't had an issue since. Maybe something happened earlier in the day or the quick release got hit and I didn't know it ... dunno, but it wasn't a fun experience.


Originally Posted by spectastic (Post 17780074)
you don't need a diagram. just loosen the skewer, lift the wheel, turn the crank, and watch that sucker jump out.

but if you wanted one

http://i.imgur.com/vVQaUjXm.png?1

spdntrxi 05-05-15 09:02 PM

dynamics... oh so fond memories... not, I barely passed.

Doge 05-05-15 09:13 PM


Originally Posted by mike868y (Post 17779955)
doge's said some ridiculous stuff, but claiming that is 140# kid puts out more power than cav may take the cake.

Cav is 148lbs - same size as my kid - was (he is lighter now). Cav publishes his power after riding some 100+ miles with a high 30mph sprint. These are totally different disciplines, I doubt my kid would be able to make the finish.
Most every track sprinter is faster with more power than Daniel. Most every pro tour rider is not. Look at other sports and check out teen power and strength. They (the pro tour riders) know this inc. Sagan, Cav and others Daniel has ridden with. If it makes you feel better there are many USA crit riders more powerful than Cav and Daniel, they just can't finish the distance Cav does and cannot handle the speed. It is not a valid comparison.

Last month Daniel was gapped at Paris Roubaix and had to close it with a time that matched Niki Terpstra KOM time bridging back on - a pro level "KOM" 30+ mph in Paris Roubaix. There was no power meter. His finish was the best 17 year old USA finish ever. It is totally valid that he is stronger and faster than a guy riding some 100+ miles. Winning races and being the most powerful rider at the end are different. This was about pulling a wheel out, but the power numbers are real.

Here is a repost of a video last year vs. a Cannondale tour pro, the current SoCal Cat 1 champ, a few USA team U23 riders on the same wheels - different frame. https://vimeo.com/113856699

spectastic 05-05-15 09:13 PM


Originally Posted by Ygduf (Post 17780096)
but if you wanted one

http://i.imgur.com/vVQaUjXm.png?1

shouldn't all the arrows cancel out? according to this diagram, this rider is accelerating to the left. and a more helpful diagram would be one that actually shows the vertical forces.

who ever drew this gets a big fat F

Doge 05-05-15 09:17 PM


Originally Posted by tetonrider (Post 17780091)
weightweenie hub from when his kid was 70 pounds???

agreed on negligence suspicion.

Its a Extralite hub got it 2 years ago.

Doge 05-05-15 09:20 PM


Originally Posted by wens (Post 17780033)
I mean, I want to see somebody draw a free body diagram of how a wheel gets driven out. Maybe cocked enough to brake rub/rub the chainstay, but I've never even heard of a rear wheel falling out from sprinting before this thread.

To my original point, the forces in the wheel should be pulling it up into the drop out. It's not like we're talking track wheels that can move in the same direction as the force from the chain.

They are not pulling into the dropout. Bike upside down the wheel jumps out spinning crank. I believe you notice [MENTION=69140]hack[/MENTION] and others having similar issues. Turns out some other (not BF posters) have too.

spdntrxi 05-05-15 09:27 PM


Originally Posted by Doge (Post 17780240)
Its a Extralite hub got it 2 years ago.

I thought the sticker looked familiar.. I use a weightweenie extralite hub as well...a new one, but I doubt it matters. I think the highest wattage I've hit is around 1100 with it.. no issues so far. Enve skewers.. parlee frame.

Doge 05-05-15 09:34 PM


Originally Posted by Ygduf (Post 17779991)
I guess you could, but that would change the angle of the stay at the hub, right? I dunno. It's weird and if this turns out to be some weird old hub that saves 2w at 30mph but is 2mm narrower than standard, that's pretty negligent to keep putting it back on the kid's bike.

We need to establish what the problem is. Other than two, same wheel, every sprint last two years. He has not lost one where he had open road. Is it negligent to use the Venge?

https://vimeo.com/117212534

spectastic 05-05-15 09:36 PM


Originally Posted by Doge (Post 17780232)
Cav is 148lbs - same size as my kid - was (he is lighter now). Cav publishes his power after riding some 100+ miles with a high 30mph sprint. These are totally different disciplines, I doubt my kid would be able to make the finish.
Most every track sprinter is faster with more power than Daniel. Most every pro tour rider is not. Look at other sports and check out teen power and strength. They (the pro tour riders) know this inc. Sagan, Cav and others Daniel has ridden with. If it makes you feel better there are many USA crit riders more powerful than Cav and Daniel, they just can't finish the distance Cav does and cannot handle the speed. It is not a valid comparison.

Last month Daniel (your son?) was gapped at Paris Roubaix and had to close it with a time that matched Niki Terpstra KOM time bridging back on - a pro level "KOM" 30+ mph in Paris Roubaix. There was no power meter. His finish was the best 17 year old USA finish ever. It is totally valid that he is stronger and faster than a guy riding some 100+ miles. Winning races and being the most powerful rider at the end are different. This was about pulling a wheel out, but the power numbers are real.

Here is a repost of a video last year vs. a Cannondale tour pro, the current SoCal Cat 1 champ, a few USA team U23 riders on the same wheels - different frame. https://vimeo.com/113856699

am I understanding this correctly? your son got invited to the paris roubaix.......

Doge 05-05-15 09:44 PM

Correct. Juniors.

spectastic 05-05-15 09:46 PM


Originally Posted by Doge (Post 17780304)
Correct. Juniors.

that's so cool. with the development team?

Doge 05-05-15 09:53 PM


Originally Posted by spectastic (Post 17780311)
that's so cool. with the development team?

Team USA
Just that :

Originally Posted by mike868y (Post 17779955)
doge's said some ridiculous stuff, but claiming that is 140# kid puts out more power than cav may take the cake...

Shows who is not paying attention.

Anyway - his wheel was pulling out, I want to fix it and Cav's setup may not do it.

spectastic 05-05-15 09:58 PM


Originally Posted by Doge (Post 17780325)
Team USA
Just that :

Shows who is not paying attention.

Anyway - his wheel was pulling out, I want to fix it and Cav's setup may not do it.

call me sally, team USA?? so he's racing as a pro?

and I think that dropout may be a manufacturing defect. the only reason I can think of for why the wheel would slide out is that the steel dropout was not properly bonded to the carbon. and because that interface between the carbon and metal dropout surface doesn't have the grooves that you find on the skewers, that would be the weak link that ends up breaking apart. I think the skewer was tight enough for it to not move, but your picture indicates that it was the dropout that gave away. I would call specialized about it.

hack 05-05-15 09:58 PM


Originally Posted by Doge (Post 17780325)
Anyway - his wheel was pulling out, I want to fix it and Cav's setup may not do it.

Boonen must put out some power on his Venge, what's he running for wheels/hubs/skewers?

spectastic 05-05-15 10:02 PM


Originally Posted by tetonrider (Post 17778860)

damn those german geneticists!

Doge 05-05-15 10:02 PM


Originally Posted by hack (Post 17780333)
Boonen must put out some power on his Venge, what's he running for wheels/hubs/skewers?

These pros (Boonen) ARE NOT putting out the peak power of domo crit riders and certainly not track sprinter. Their average power is higher - different game.

Anyway I just asked junior - if it came down to it trade wheels or Venge. He said Venge.

Doge 05-05-15 10:05 PM


Originally Posted by spectastic (Post 17780330)
call me sally, team USA?? so he's racing as a pro?
...
I would call specialized about it.

No - Team USA juniors. Not pro.

Yes - calling Specialized. That [MENTION=69140]hack[/MENTION] had issues is also important data point. I posted here for ideas and feedback. Seems it happens a bit.

spectastic 05-05-15 10:08 PM


Originally Posted by Doge (Post 17780349)
No - Team USA juniors. Not pro.

Yes - calling Specialized. That @hack had issues is also important data point. I posted here for ideas and feedback. Seems it happens a bit.

cat 1? how do they make the selection for the team?

Doge 05-05-15 10:24 PM


Originally Posted by spectastic (Post 17780356)
cat 1? how do they make the selection for the team?

Team USA is juniors 17-18, U23 and then Olympics.
Cat does not matter. Winning certain junior races does. Politics seems to. Winning some adult races matters too - but less.

The top junior races are more competitive than the Cat 1 races. VOS, Sea Otter and National top riders normally have a few Cat 2/Cat 1 wins. For juniors there is no mandatory upgrade. Kids sit on their upgrade points. Daniel had triple what he needed before going to Cat 2, Gage maybe quadruple. Adrian chose to race NRC and NCC rather than juniors so he upgraded and finished a semester of college - he is a Cat 1 and until Brandon came along this year the undisputed top junior - likely riding for Cannondale next year. Brandon did not upgrade although he has some 80 points (double). There are no points for Euro races. Its all too complicated and I don't totally get it. We parents all know who is best for what. They don't ask us.


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