Classic & Vintage - Long wheelbase bike

I recently bought an early 80s Motobecane Mirage. After taking it for a 10 mile ride tonight, I was very impressed with the ride and handling. I've never ridden a bike that handles like the Moto- it is so willing to change direction yet extremely stable. It is the complete opposite of the Giant OCR3 i just sold. Looking at the bike i notice that it has a much longer wheelbase than my Peugeot PKN10 or my LeMond by a bit more than 3 inches. The chainstays are noticeably longer on the Moto. How and why is it that longer wheelbase improves handlling?

Check the trail on the fork, it really can make or break a bike IMHO. Most of the newer bikes appear to have straighter forks with less trail. I much prefer the older more relaxed geometry that was prevalent in the mid 70's sport bikes. I have had a couple of long haul tour bikes that rode like a train on rails, they weren't quick handleing but very comfortable for long all day riding. Too many of today's bikes are aimed at the Lance wannabees and the tri riders which is a whole different style and type of riding. You can have a long wheel base with a fairly short trail, head tube and seat tube angle also play a part in it. Relaxed angles slow the steering a bit but give increased overal comfort.

Aaron:)

The angle of the headtube on my moto is more relaxed than the peugeot but the amount of trail in both forks is about the same.

The angle of the headtube on my moto is more relaxed than the peugeot but the amount of trail in both forks is about the same.

Do you mean to say that then amount of rake (aka offset) of the two forks is about the same?

BTW, trail is a pretty sensitive function. "about the same" might still represent a significant difference.

Road Fan

I use the term "trail" reluctantly. What i'm really referring to is the amount of castor angle in the fork.

Yep, long wheelbase bikes ride nice. I recently switched from my racing bike with a sub 40' wheelbase to a hybrid that is 42 1/2' long. What a nice ride. My hands and wrists dont hurt, my butt doesnt hurt, no more jolts from bad roads. I think most people would benefit from longer wheelbase bikes. They would enjoy riding more with less aches and pains. But fashion drives everything including bikes. Look at the fixed gear craze and people riding track bikes on city streets. Give me a bike with long wheelbase, plenty of fork rake and clearence for fenders. And I'm plenty happy with 10 gears too.

A great number of things can effect the handling and the ride of a bike. Even the seat tube angle can determine how much of a riders weight is ultimately distributed to the front of the bike and onto the fork, as can the chain stay length. And the head tube angle can also come into play along with the actual rake of the fork itself. Fascinating to consider all the variables, and see how they effect each of my own bikes.

I too much prefer what is basically the more relaxed geometry of a classic "touring" bike. The extreme end of relaxed geometry might be the British Roadster style bikes with frame tube angles at perhaps 63-68 degrees.

I haven't yet aged (perhaps I should say "matured") to where I can appreciate the extremely layed back angles of a Roadster bike, designed entirely for the very upright seated position of course, but plenty of time to further temper my tastes and needs in the future. One must admit that people riding old Raleigh roadsters always seem to be very comfortable and contented. There must be much to like about that ride... and the less hurried riding pace too, I suppose. Those bikes also do handle with superb stability.

IMO we're still suffering the lingering effects of the "crit bike craze" of the late 80s. (I had one made in '87 or '88 and spent a season trying to convince myself it didn't suck). Lots of folks just don't think a bike looks racy unless it has a tiny little bend in the fork blades and a rear wheel brushing the seat tube. By '89 or '90 I had frames made with the "stage race" geometry that LeMond had sort-of popularized. It was a tad harder to muscle those bikes through a fast "S" turn in a criterium, but they were otherwise much, much better than the typical race frames of the day, IMO.

Today, long after the racing career ended, I find that my favorite bikes come with a 73 or 74 degree head angle and about 60 mm of rake, for a trail somewhere in the neigborhood of 40 mm. This results in what I consider perfect handling, although I ride 27 mm tires at a minimum and am told that trail that low results in instability with typical <25 mm tires. I haven't tried it so don't know, but I do know that I don't especially care for the 60+ mm of trail typical on a modern "performance" bicycle, regardless of tires.

I concur with the general sentiments of this thread. For clarification, fork trail is specifically defined as the distance along the ground between the front tire's contact point and a straight line projection through the center of the steerer tube. This is a function of head tube angle, fork length, and fork rake. Fork rake is the forward displacement of the front axle resulting from curvature of the fork blades.

My Bianchi and my (now my son's) Peugeot PKN-10, both ca. 1980 models, are about as short, upright, and stiff geometries as I care to ride. For a long ride with a few bumps, it is hard to beat the old relaxed geometry framesets, either touring bikes of the 1970s or long distance road racing bikes of the 1960s.