I have a Gios Compact Pro, which allows the wheelbase to be fine tuned. There is a noticeable difference in the quickness of the handling when the wheelbase is shortened, the bike responds more quickly. It is less obvious if there is a reduction in stability, any adult road bike with 26” or larger wheels is going to be plenty stable.

[QUOTE=LeeG;23463169]It's the fear. I definitely control the speed from the top. I start to get real nervous as I approach 40mph. I try to stay relaxed and not allow myself to get panicky. Then it's a balance of easing into braking when necessary but still push myself into the discomfort so I'm not riding the brakes the whole way down. I'm glad you mention body position as I was just wondering if how much I might be pulling back from the front? I'll read up on body position for descents. Feel free to shout out any pointers you may have.

[QUOTE=Mr. Sawdust;23463219]First off 40 mph is not slow and just because gravity and a good tuck can take you faster why the hell would you if it gets you nervous? Basically at those speeds on road tires you’re ballistic as much as you’re actually rolling on tires. Hop the bike a few inches and you’re not touching the ground for 25’. Fly over chopped up pavement or gravel and any lateral movement can give you a two wheel drift as unsettling as on a wet road. What size tires are you on?
I’m too old and without the reactions to ride those speeds like I did in my 40’s. So I don’t. Your nervousness is common sense talking to you in that you don’t feel n control.

Kinda related. I was a mediocre bike racer. A strong Cat 3 in the 80’s. I don’t have a high pain threshold and often imagine worst case scenarios but I rode a lot with the local racing club and placed well a few times. One time I needed to take that common drug for poison oak, prednisone I think, Anyway Day two on prednisone and I’m a total maniac doing multiple training exercises in one day to a level of aggression that is not at all normal for me. As I’m flying down some long sweeping high speed descents totally fearless I realized this must be what my racing buddies feel like. I was inches from the edge of the road and if I went offf it would be a hellacious long tumble but I didn’t care, wasn’t worried. My skill was no better but all the internal anxiety was gone. To me it felt like a killer instinct was coming out. No fear.
Do enough stuff that’s at the edge of your skill and eventually you find the edge you shouldn’t cross. I’d suggest enjoy playing with the bike at the lower high speeds where you feel in control and see where the edge is there. See what a full stop at 30 mph is like, what maneuvering is like so you are in control where things are fast but not so fast you start tensing up. Do gentle s turns going 25 mph, do controlled braking with one or both brakes, play with short skids on loose dirt. When you’re flying down a long descent it’s almost flying and large lateral movements can send you ass over end. Kind of like downhill skiiing you look where you want to go and let the bike take you there. Anything you can’t hop over or swerve around you’re plowing through and road size tires aren’t the best plows.
Things happen awfully fast at 40 mph helmet or not. No reason to be there if it makes you nervous.

Hmmm, 'bents you say: My Saki high racer (700c wheels front/rear, although I made a 20" and 24" wheel for the front as a test) is fast, yep, probably the fastest bike I've ever abused, but wowza is it hard to learn to start. Easy cruise on the flats at 20 mph, and is fun to casually pass other roadies. Never had the courage to take it down THE five mile 1500' hill, as I would be breaking the 60 mph speed limit and soiling my diaper, plus the busy intersection at the end comes just at the end of a steeper part. Turns? Takes a few tangles to learn to keep the feet out of the way. When I change to a smaller front wheel it gets more twitchy, but easier to start/stop. Now my HP VeloTechnik Grasshopper 'bent is easier to ride (20" wheels) and a bit less wheelbase, and on my single hill test it too took off like a goosed rocket. Disc brakes thankfully, and like a freight train on tracks for stability. 50 mph sitting a few inches above the asphalt is 'exhilarating', or not. I'm done with 'bents though, and both will be up on the chopping block next month.

Oh, wheels base? I can change the base on my '79 Serotta Crit bike by using the dropout adjusters. Even 5mm feels different - if a shorter WB it gets a tad, er, more 'attention required' but not twitchy. I've gone near 10mm and can definitely feel that the longer WB is more-better stable, but it's a crit so never a century ride.

Performer Saki High Racer 'bent
HP Velotechnik Grasshopper 'bent
Serotta Legend ST
Serotta CSI
Serotta Fierte
Serotta Councours (sold it, darn)
Serotta Criterium circa '79
Nishiki Prestige '83
Waltly Custom Ti Mtn bike
Land Shark 650c