Driver clubhead speed slow, but iron clubhead speed fast?!

I recently bought a Blast Motion sensor to help improve my putting and full swing tempo. On the range, I put it on my 8i (go to range club, which I carry ~155) and it measured club head speeds of 87-90 mph. A short while later, I put it on my driver and was surprised to find speeds in the range of 100-102 (I usually carry driver ~265). Based on data I've found, it seems like my driver clubhead speed is low relative to by irons, and I was wondering if there was a simple explanation of what I'm doing to cause that. Some helpful tidbits of info:

I'm playing fitted clubsI have a fast tempo in the 2.2:1 range (as opposed to the "ideal" of 3:1)I have a long swing with a tendency to overswing and early extendRecognize that this isn't easy to diagnose without a swing video, but wondering if there are any simple explanations. My (admittedly uninformed) guess is that my swing is more compact on the short irons and allows me to accelerate faster, as opposed to the driver which gets a little long and has to work around early extension.

Really appreciate any thoughts!

if you are carrying 265 then ur ss isnt 102

This is spot on. Either you are severely over-estimating your driver carry, or the device you are using is not accurately measuring your driver swing speed. At 100mph swing speed, even with optimized launch conditions, you’d be lucky to top out at 250 yards of carry.

A general rule of thumb at your 8i swing speed is that you should be swinging your driver about 20mph faster than your 8i, or in the 110mph+ range.

My irons are about the same as yours, and driver is about 105 with an average carry 255 to 260. That’s not including badly mishit shots.

102 is about 250. I was stuck there for years no matter what or how I hit, 250.

appreciate the responses from all. Philomathesq, your data point on typical comparison between iron and driver SS is very helpful. Any feedback on what swing characteristics typically this type of situation would be much appreciated!

Many things can contribute to less-than-optimal driver swing speeds. Most people have a different driver swing than iron swing, so your driver swing could be less efficient than your iron swing.

Another possibility is a mental-physical limitation. Your brain may think you will injure yourself trying to slow down a 110mph driver swing, so it puts a limiter on your speed.

It is impossible to tell what your issue may be without much more information. But, I would start by measuring the swing speed of your other woods and hybrids and see where they come out. Knowing where your speed compression starts (I.e., 4-iron or 3-wood or driver) could help in determining what issues you may be having.

what loft is your 8 iron? Id lean on saying the device is measuring driver wrong, 265 carry translates to about 108 swing speed. Keep in mine the heel is not traveling as fast as the toe, so depending on where the device is measuring from, it can throw the numbers off a little.

Do you have to tell this device club length?

This is a great thought. Yes, it does - it seems to calculate CHS based on measured hand speed. I should probably double check club length inputs.

8i lofts are traditional, so 39*.

My initial diagnosis is overswing + disconnected arms --> club stuck --> early extension to clear room --> slow down hands to flip and meet ball. Feel like shorter clubs impact this less meaning I get more of my natural speed.

I have the same issue but have a launch monitor for the data. I also have videos if it will help. My iron swing speed and ball speed is good (ie 6i is 95 club speed and 132 ball speed). Yet my 3W club speed is 92 and driver is 97. And if I use my 8i speed plus 20mph then my driver should be 109. I have the data from both trackman and Mevo and it’s consistent. I know I do some early extension with woods but is that really the reason I lose that much speed? Any ideas or help would be appreciated. Thank you. 

I struggle with this too.   6-iron around 80, Driver in low 90s.  Just a bit of self-analysis:

1. Intent / Angle of Attack - By nature, I'm a sweeper, not a digger.  I think I swing irons harder knowing a collision with the ground is imminent.  Driver and FWs, I tend to sweep.

2. Length of Club - Related to #1, I think 44" drivers and 43" FWs just feel long to me.  I can't lever them the same way I do my 6 iron.  Need to Nike it and just do it...

3. Good warmup - Last weekend, I went to the simulator and had a two hour session.  Once warmed up, I got my driver up to 95 club speed.

4. Barrier Removals - I think doing #3 above is good.  Once your mind knows it's OK to swing faster and your body complies, It will let you do it more often.  Hopefully on the course...

Closer the clubhead speed is to hand speed , the less difference the increased length of shaft will have on increasing clubhead speed 

I would say the sensor is likely overestimating the iron speeds or underestimating the driver speeds. I swing a 8 iron around 90 and driver is 118-119. 

Most people have a speed limit on how fast they swing.  The limit could be due to physical reasons such as light grip pressure, inefficiency, poor face control etc. or it could be because you haven't yet created the neuropathway to swing faster.   Most people have both and I would venture to say that the latter is at least partially the result of the first.  Fix your swing and get more efficient first.  Not only will your cap drop you will naturally hit it farther with a more efficient motion.  Once you get there, start working on training yourself to swing faster.  It's the same thing in the gym...when you lift heavy, part of what happens is you develop new neuropathways that train your muscles to contract harder.  You need to train your muscles to move faster.  

Focus more on the ball speed number vs. swing speed. Almost all launch monitors have some variance with how they measure swing speed but they should be on the money with ball speed.

According to Foresight optimal ball speed for low speed and high speed players are:

Driver: 141mph and 6iron: 114 mph  (1.24 multiplier from 6iron to driver)

or

Driver: 165mph and 6iron: 128mph (1.29 multiplier from 6iron to driver)

If you have jacked lofts on your irons I would expect about 5-8mph more ball speed with your 6iron but if your ball speed numbers are a similar ratio then you do NOT have a swing speed comparison issue.

https://www.foresightsports.com/sites/default/files/files/Understanding Ball Launch Club Data.pdf

One point to consider, since the driver swing speed keeps coming up relative to the 250-260 carry—Blast is mounted on the end of the grip and so doesn’t pick up the additional speed from the closing of the club face that say Trackman would (which measures the speed at the point of impact). It would seem that Blast could only measure the estimated speed of the hosel, which would be a bit slower. The difference would be bigger on a driver because the club is bigger than the blade of an iron. 

Also, it may think of the length of the driver slightly different. Keep in mind the sensor is on the grip so it has to guess how fast something, say 45” away from it is moving (simple math, but the crux of it is how far). If the way it measures 45” (say to the bottom of the club) and the way you or your manufacturer measures it differs, then speed will be wrong. A 1/2” of misreading the shaft length could create the changes people referencing. 

With that said, youre pretty close to my numbers and on a bad day I might sneak down to 102 and might hit 110 with the next swing, so could’ve just been the way your swinging on that day. My irons are pretty darn consistent in speed on account of being a good deal heavier. Some people just have different ratios.