In general, I don't know why one would do this.
Especially men.
Here's what Sheldon Brown has to say, and I tend to agree:"If the saddle is tilted down in front, the rider will tend to slide forward onto the narrower part of the saddle.
Women who are riding on saddles that were designed for men frequently tilt their saddles down.
This will relieve some of the discomfort from the saddle itself, but creates new problems: The downward slope of the saddle causes the rider to tend to slide forward, and this can only be counteracted by pressure on the hands.
Thus, poorly-angled saddles often are the cause of wrist, shoulder and neck problems, due to carrying too much of the rider's weight on the hands."
Lennard Zinn mentions that a "very slight" tilt in either direction may be optimal for some riders; but no more than ~2 degrees.
Basically the same reasons that Sheldon Brown mentions.
The downward forward tilt adds pressure on the arms, back, and shoulders due to sliding forward.
You want your "sit bones" to be on the widest part of the saddle.
If you slide forward, the pressure will shift from the sit bones to the perineum; and that's probably a bad thing.
There are special cases for tilting the saddle nose downward; but for the general rider it's not necessary.
bicycles.stackexchange.com/users/None/
I had some saddles that in some bikes were best with a slight tilt down, otherwise they would crush my perineum.
One of my current saddles (Brooks) is tilted nose-up, otherwise it is very uncomfortable because I feel thrown forward.
In the end, I think it depends on: Rider's anatomical shape; Saddle shape (in case of a leather saddle, might change over time);
Overall position of the bike (if you put the saddle on different bikes, optimal tilt might vary; Cruise speed of the bike.
If you pedal hard, tilt down might be fine.
If you pedal slowly and upright, most probably tilt down would be very uncomfortable.
bicycles.stackexchange.com/users/2355/heltonbiker
Tilting the saddle forward relieves lower back pain.
Don't take my word for it; here is a clinical trial in the British Journal of Sports Medicine:
http://m.bjsm.bmj.com/content/33/6/398.short
They tilt the saddle forward a lot (10-15 degrees), and show big improvements in back pain.
I had this problem and it worked for me.
If you look at the spine position drawings it's pretty obvious
why: tilting forward means your back doesn't have to round so much.
Though 10-15 degrees is a bit extreme I think.
5-7 degrees was enough for me.
bicycles.stackexchange.com/users/14050/alzy
I tilt the seat down slightly to make it much more comfortable for me to ride, When the seat is horizontal, I find I end up with pain from that narrow part of the seat pressing where it shouldn't.
Tilting the seat down means that I am only in contact with the slightly wider part of the seat.
The way I have my bars set up means there is no possibility of sliding forwards on the seat.
While my bike is a road racer, with bars and seat set up accordingly, I use it for commuting - about 35 miles a day.
bicycles.stackexchange.com/users/2077/Rory Alsop
Quite a few bike messengers tilt their saddle forward a little bit.
Personally, I do it because if you're riding a long distance, it will put more weight on your arms, tilt you forward, make you more aerodynamic
, it's better for speed, and it takes the weight off of your "sensitive areas".
There are some pretty interesting studies about riders with perineum numbness.
Tilting the saddle forward will help relieve the stress on the mentioned area, and put more of it on the sitting area.
BE CAUTIOUS
: this will put considerably more stress on the arms and shoulders.
Be prepared.
As with anything else, your body will adapt naturally after a while.
bicycles.stackexchange.com/users/11484/KidAlleyCat
For time trialing, or other riding where the rider will be in a very aggressive position for extended periods of time, a slight tilt forward can relieve unnecessary pressure on the perineum.
bicycles.stackexchange.com/users/3458/prototoast
I have what most people would call an extreme forward tilt on my saddle.
I use a racing saddle with a large cut out.
The reason I use this angle is to stop me getting pressure on the perenium.
I have been riding like this for around twenty years to the derision of "experts" wherever I go.
I recently rode the new forest epic.
My first sportive with no training in 6.01 with no ill effects and no nasty numb areas.
I sit on the top wide edge of the seat and the nose drops away at that point and makes no contact with sensitive areas.
My riding position is aggressive but feels comfortable with my body almost acting like a stressed member with weight spread between between balls of feet on pedals, hands on hoods and bum on top edge of saddle.
I understand there may well be loads of studies done on bike fit and there may well be a bible on the ultimate riding position, but maybe more time should be spent looking at "people"in relation to bike fit.
I love riding my bike.
I have a reasonably decent boardman roadbike.
I do not own a car
so I use my bike to commute, for recreation and fitness.
I love my wacky but effective riding position!!!?
Enjoy your riding everyone:-)
bicycles.stackexchange.com/users/13296/steve griffin
I have seen a few people do this where their saddle was angled down a bit. Why would someone do that?
What are the advantages of angling your saddle down?
bicycles.stackexchange.com
<saddle>
bicycles.stackexchange.com/questions/8131
bicycles.stackexchange.com/users/1473/Chris Belsole
Tilting the saddle forward is generally done for reasons of comfort and especially for long distance riding. I straight saddle can cause back pain, discomfort to the perineum and crusch your "sensitive parts". Bike messengers often tilt their seats forward. However, it does cause the rider to slide forwards putting more pressure on the hands. Some riders tilt their saddle forward to relieve seat or back discomfort, shift pressure to the hands or adjust to a more comfortable posture. Other riders find a tilted position more comfortable for fast riding in a more aerodynamic position. Tilting may result from using an unsuitable saddle, e.g. women riding with a men's saddle. Experts suggest that some tilt may help, but too much can create new problems.
Some riders tilt their saddle forward to relieve seat or back discomfort, shift pressure to the hands or adjust to a more comfortable posture. This may result from using an unsuitable saddle, e.g. women riding with a men's saddle. Experts suggest that some tilt may help, but too much can create new problems. Some riders find a tilted position more comfortable for fast riding in a more aerodynamic posture.