Same limbs on different length risers?

[threeunder]

How does the length of a riser affect the draw weight of a set of limbs.

Let's say I have a recurve with a 17" riser and the limbs are 50# @ 28".  What would my draw weight be, generally, on a 15" riser?

[old_goat2]

Depends on the riser design. With ILF bows, the limbs usually go up or down one pound per inch of change of the riser. For instance going from 17" to 19" the bow will drop two pounds and vice versa. But with most bolt down bows that I know of, the bowyer will change the limb pad angle on each of the lengths of risers they build so that the draw weight stays constant. I'm sure there are exceptions to this but I don't know of any off hand.

[Bjorn]

Approximately 52# based on a 2" riser length difference.

[cacciatore]

I guess you are talking about a Silvertip,using the old limbs on the 15" riser you are going to gain 2#

[Orion]

On Bear T/D risers, it's about 2# per 4 inches of riser length.  The limbs are even marked that way.  It may be a little more or less with other takedowns, but the direction is always the same.  Move to a shorter riser and the poundage goes up. Or, conversely, move to a longer riser and the poundage goes down.  

Of course, if you're talking an ILF bow, there is some adjustability so you could conceivably crank the bow to the same weight with either length riser.

[Wheels2]

I picked up a TT and found that on a 19" riser, the limbs are pulling 2# less than marked for a 17" riser, just as the shop had predicted.  Their ILF limbs are marked for a 17" riser.
The ILF limbs have a 10% variance from marked poundage in addition to the difference caused by different riser lengths.  Check with the manufacturer as some of them are labeled at lowest poundage and can be adjusted up while others are marked at max.

[cacciatore]

Orion,I thinks it depends on the poundage, the highter the more they gain per inch.
I have 2 set of original Grayling white tip limbs that are both marked 60# on the B riser and 65# on the shorter,4", A.
Then I have some Rose Oak limbs marked  60# on the B and 64# on the A,  again a pair of RO  55# on the B and 59# on the A,while a pair of 53# on the B makes a56# on the A.
Sorry for the boring answer.

[Orion]

Yep, Felix.  Initial weight does make a difference.  Most mid-weight Bears vary about 2# per one riser length change, but the difference does go up with heavier limbs.  That holds for all other bows, too, of course.  Not the 2#, but the proportional increase or decrease in weight relative to initial weight.

[threeunder]

Yes.  It is a Silvertip.

Picked up the 17" Riser that was on the classifieds.

I have a 58" (15" riser).  I'm wondering if I got a set of limbs for the longer one if they would be swappable to the shorter one.

Anyone know?

[Orion]

Maybe.  Maybe not.  It would be very close. It's my understanding that Dave makes each set of limbs to fit a specific riser.

[StickBowManMI]

WOW I stumbled upon this question at just the right time. I haven't shot my High Sierra since Ron Fox made it for me at least 10 or 12 years ago. I have been shooting my longbows and felt the urge the shoot the recurvebows.I took out the high Sierra with its two sets of limbs and the original limbs made a 62inch bow at 60LBS @ 28inches. The second set of limbs that I had Ron Fox make were 54Lbs @27" and made a 58" bow using the same 19 Inch riser. I did not realize that this would actually affect the actual draw weight of the shorter limbs or how much the actual weight for the 58" bow. what should I due? Any suggestions. hopefully someone will have an answer for me. Thanks,Tom

[Thumper Dunker]

Had some rainy day limbs that was 52@28 they was on a 16'riser. Had George make me a 14" riser for them and they are right at 55@28'

[cacciatore]

You can swap from one to the other since they are of the same dexterity,but the contour lines could be different. This is just for the look.

[kat]

I have interchanged limbs between a 60", 62", and 64" bow. The risers were 17" and 19". Can't say for sure about a 15" riser, but I do believe Cacciatore is correct. Dave builds the bows by hand, so the fit isn't the same as a CNC machine would be, but they have been really good in my experience.

[Orion]

Stickbowman:  If I understand you correctly, both sets of limbs were made for the same 19-inch riser so they will draw what they say they draw on that riser. Doesn't make any difference that one set of limbs is shorter than the other.  They were made to draw a particular weight on that 19-inch riser.  

However, if you put either set of limbs on a shorter riser, each will draw heavier than marked, and the resultant bows will be shorter. Hope that makes sense.

[StickBowManMI]

Thanks Orion! I guess that I need to start working out to shoot these bows again.