Riser Length

[snowplow]

So I've been mostly a 50's recurve guy. So light small longbow risers. So naturally I am comfortable with small light risers and shorter overall lengths. For no particular reason than that's what I know. I am playing with 3 piece stuff now.

What do I need to know about riser length?

Would a short riser/long limb have a smoother longer draw? Is long risers just for more weight? How does a long riser/short limb 62" bow compare to a short riser/long limb 62"? School me up guys!

[McDave]

People who want a longer recurve in order to increase accuracy don't necessarily need a bow with a long draw length.  The maximum efficiency of a recurve occurs when the recurved part of the limbs is working, i.e. flexing.  If the recurved part of the limb is not flexing, it might as well be a longbow.  If you put long recurved limbs on a short riser, it will increase draw length.  If it increases draw length to 32”, and your draw length is 27”, you won't be getting the full efficiency of the bow.  OTOH, if you put shorter limbs on a longer riser, draw length can stay in the optimal range desired and the efficiency of the bow will be maximised.  For any combination of limbs and riser, the bowyer should be able to tell you what the optimal draw length range for that combination is.  Stay within the recommended range for best results.

[snowplow]

People who want a longer recurve in order to increase accuracy don't necessarily need a bow with a long draw length.  The maximum efficiency of a recurve occurs when the recurved part of the limbs is working, i.e. flexing.  If the recurved part of the limb is not flexing, it might as well be a longbow.  If you put long recurved limbs on a short riser, it will increase draw length.  If it increases draw length to 32”, and your draw length is 27”, you won't be getting the full efficiency of the bow.  OTOH, if you put shorter limbs on a longer riser, draw length can stay in the optimal range desired and the efficiency of the bow will be maximised.  For any combination of limbs and riser, the bowyer should be able to tell you what the optimal draw length range for that combination is.  Stay within the recommended range for best results.

Thanks Dave. I was just asking because I have a longer draw (30.25).

"If the recurved part of the limb is not flexing, it might as well be a longbow." This made me think of something that I've wondered for a while. What is the point of a static recurve? Is it just a short bow/string angle thing?

[McDave]

I really have no experience with shooting a static recurve, but my understanding is that the static recurved ends accomplish two things: they reduce finger pinch at full draw compared with a longbow of the same length, and they store power similar to working recurve limbs.  The static ends start out facing away from the shooter, but as the bow is drawn they rotate into a more vertical position.  When the string is released they spring back into their original position, thus releasing a greater amount of stored energy than comparable longbow limbs.  Since they have become somewhat of a novelty item, I would assume they don't release as much energy as comparable working recurve limbs, although they remain popular enough that they are still being produced today by a few bowyers.

Going back to your original question, the bowyer will normally specify a recommended draw length range, say 28-30” for a particular recurve.  Another recurve might have a range of 30-32”.  This means that for the first bow, the recurved ends will not be optimally extending if the bow is only drawn 27”, and will stack if it is drawn much beyond 30”. Normally this means that the bow will draw more smoothly toward the lower end of the range, but won't quite maximize its performance until it is drawn to the upper end of the range.  So if your draw length were 30” and you wanted to maximize performance, you would pick the first bow; if you wanted to maximize smoothness, you would pick the second bow.  The two bows could be the same length, but the first bow could have a longer riser than the second bow.

[streamguy]

I think McDave said it pretty well.  I'd add 2 thoughts:

1. worth noting that speed/cast is only one part of "performance"
2. some (I think very limited) bowyers modify construction to maximize speed at the purchaser's draw length.  Kirk Lavender (Bigfoot Bows) used to build the limbs with differing power lams, limb design, and/or tip wedges to accommodate the individual.  so you can design a longer bow that to have better performance (and start stacking) at a shorter draw length