I just got done shooting my arrow through the chrono again.

Back in July I was getting 175 ft/s ave
Now I'm getting 156 ft/s ave

Only thing different is my bow .. and chrono are colder now than they were in july.

Same everything including draw.

20 ft/s?!

Is this normal?

Actually you are probably not drawing what you did in the warm weather. I find that I loose over an inch of draw with heavy clothes.


Another item is unless you are using artificial lighting for your chron the shadow detecter might not be work as well.

Mike

Hey John, interesting topic...time to get out the coffee mug.

It is more than  likely your chrono. Most digital devices unless protected don't function well in cold. This would be especially true or worse if display is lcd.

Don't know about you guys but I move alot slower in the cold.

QuoteOriginally posted by wingnut:
Actually you are probably not drawing what you did in the warm weather. I find that I loose over an inch of draw with heavy clothes.


Another item is unless you are using artificial lighting for your chron the shadow detecter might not be work as well.

Mike

Good thought.

but... I was just wearing a light flannel and I know my draw is "normal"

I'll tell you what.. I was looking and measuring just to see what was going on.

In both cases the chrono was outside in partially overcast days with the diffusers set up.

Thanks for ideas so far guys.

QuoteOriginally posted by cbCrow:
It is more than  likely your chrono. Most digital devices unless protected don't function well in cold. This would be especially true or worse if display is lcd.

It is a LCD display.

Curious why a LCD display would mess up the speed more in the cold?

No reason a bow should slow down in the cold.  Matter of fact, I would think it would actually stiffen slightly in very cold temps and speed up a touch.

I kinda thought that too Jeff.

But on the other side, the old "molasses in Jan" saying comes to mind.

Limbs might not want to bend back to shape very quickly.

Don't know which affects things more...

lcd=liquid crystal display. I have a prochrono and had same problem a couple of years ago so I called and that is what the tech said was more than likely the problem. When it warmed up a little everything came back fine. Temps were in the lower 40's when it happened.

mine's a pro chrono too.

I just paper tuned again and everything looks good.

sooooo.. I figured if anything the arrows would be more stiff and show it...nope.

So I was thinking the cold might be affecting the epoxy in the glass of the limbs, but the arrows should still show stiff if that's the case.

Probably just the chrono.

Thanks  

I'm no expert on archery chronographs, but have a pretty good understanding of electronics in general.  To measure arrow speed there has to be an oscillator of some sort in the chrono used to measure arrow speed; and unless it's fully temperature stabilized (expensive and not likely in a consumer grade device), it will shift a lot with ambient temperature shifts.  That, plus the denser cold air (slowing the arrow down a touch) and possible decrease in limb elasticity may very well all add up to a 20fts difference.  Maybe the manufacture of the chrono could shed a little more light on the problem.

I would if possible do all my chrono testing indoors in a climate controlled environment. Electronics are very temperature sensitive.

Strap or tape a couple hand warmers on your Chrono for a few minutes and try again!

QuoteOriginally posted by lablover:
Don't know about you guys but I move alot slower in the cold.

Me too! I don't notice that my arrows go slower, but I sure do!  

Check may be also the bow draw weight ,like some prople,some bow loose power with age

My shooting doesn't lose much speed at all.  I lose quite a lot!  :D  

In all seriousness, it sounds like you've already heard the real, hidden issue: you probably aren't getting the last inch or so of draw.  It will FEEL like you are (perceived effort), but you probably aren't due to extra clothing.  Now, that's if you are using modern fglass bows.  With a selfbow, esp a water-loving wood such as hickory or dogwood, it might actually be that the bow has absorbed moisture from the cold humidity and has grown a bit more sluggish.

This is preferable to the other extreem, if you heat with wood and keep your bows inside.  In this case, the bow sometimes explodes in your face due to excessive dehydration from very dry wood heat.  Don't ask...

QuoteOriginally posted by Piratkey:
Check may be also the bow draw weight ,like some prople,some bow loose power with age

Other than a wooden bow, I've never seen anyone able to document any measurable loss in draw weight due to age.

Maybe try keeping the chrono inside until the last minute, then run it out and try.  See if having the electronics warm changes anything.  Or go to an indoor range.  Set everything up, but leave the bow in the vehicle.  Go out and shoot it as soon as possible so that it is cold, but the electronics are all warmed up.

What is cold? 40 isn't even cold around your place! I think you lose 1.237 fps per degree Celsius. Actually, I would think the materials would stiffen and react more slowly, but I'd think it would take a greater temperature drop. Maybe below freezing?