Bow Speed at Short Draw Lengths

[PathFinder]

Over the summer I've gone through 4 different bows. I've got a stubby 27" draw length, but no problem shooting heavy draw weights. Over the course of the summer shooting and testing each bow I used the theoretical calculators on the web to estimate arrow speed, but a chrony showed that some manufacturers build components just to reach IBO speeds, and leave it at that. Others take into account draw length changes when they design their cams.
First off, my 2006 Bowtech Old Glory. Set at 70/27, shooting a 375 grain arrrow at 285. Not bad for an old bow. Next, I bought a used Bowtech Insanity CPX. At 60/27, shot a 410 gr arrow at 275. Pretty close to theoretical values. After the limbs delaminated, I bought a Matthews Chill R. It was a joy to shoot (very stable, forgiving, and smooth). With the same 410 gr arrow, at 73/27, it shot only 248 fps! I was at the pro shop getting a sight tape made, and couldn't believe how slow it was. We verified that it was indeed only shooting 248 fps with a couple more shots. I had heard that Hoyt makes smaller cams for shorter draw lengths (so cam geometry remains the same) so I immediately walked over to the bow rack and grabbed a Carbon Spyder ZT Turbo in my draw length. I shot it through the chrony and at 70/27, it shot 296 with the exact same arrow! Needless to say I left with the ZT Turbo. The difference in the field is impressive. As far as accuracy, I shoot the Hoyt just as well, maybe better. Speed may not be everything but the 248 fps was a joke. I thought this was pretty interesting, and something to consider when buying a new bow.

 

[velvetfvr]

Mathews has inflated but that bow wasn't in tune and a Mathews can still hit their ibo speed. The Hoyt will be more efficient especially with their #2 cam, it's there fastest in relative terms. I've forgot bow speed mostly. I want Momentum, that's what gets you the best penetration.

 

[5MilesBack]

Same thing happens to some bows when you get into the longer draw length at 32+. I bought one bow, a 335IBO bow that wouldn't shoot more than 313IBO taking everything into the equation and no matter how much tuning I did with it. It was 13fps slower than my 316IBO bow. Everything changes at 32+ draw lengths. I'm sure some bows change the same on the downward side as well.

 

[kpk]

I have a 27" draw too. Bowtech and Hoyt have always seemed to shoot the best for me as well.

 

[MattB]

Hoyts tend to be pretty fast at shorter DL's as they have DL-range specific cams. My new carbon speed bow at 27.5"/68# shoots a ~440 gr. arrow about 275 fps.

 

[Bowhuntr64]

Yeah, my Hoyt CS30 is shooting well for my short DL of 26.5". 73 lbs, 378 grain arrow, 298 fps.