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1950 Series ‘C’ Rapide (Trials Sidecar Outfit)


vibrac

Well Known and Active Website User
VOC Member
A source of great sadness I never saw it blast up blue hills mine perhaps I should reconnect the comet trials chair...
 

vibrac

Well Known and Active Website User
VOC Member
You may think the track is a bit wide for a trials outfit untill that is you try to go up a Cornish hillside lane section with a narrow 'conventional' trials outfit and find one wheel on the center of the track and the bike in the RH rut with the passenger hanging out like a racing yacht pilot and your right leg mowing the grass (or rocks!) on the bank
A well thought out conveyance that needs to be kept as is ...a basis for a VOC trial team for a Lands End?
Note the position of the eccentrics
 

Ian Savage

Well Known and Active Website User
VOC Member
Fitted on 'inside' so it doesn't get knocked off by a passing rock!
As the ad says 'built without compromise' lots of detail like this and the Scintilla mag.
 

davidd

Well Known and Active Website User
VOC Member
And on solo trail. Why?
In dirt, the trail often goes negative. If you drop a plumb bob down the axle line you will find that the contact patch for the tire on one side of the axle is equal to the other side. The plumb bob turns out to be the centerline of the contact patch. If you are calculating the trail you often start with the center of the 3-4" contact patch as one marker and the second marker would be where the rake centerline crosses the pavement. Join the two and that is the trail.

If you think about riding your bike in a paved parking lot your trail will be fine and provide good self centering. If you dive off the pavement into sand, for example, things are OK for a second, but as the bike sinks into the sand the steering gets heavy. Then the handlebars start kicking to one side or the other. What has happened is the contact patch in the sand has gotten very, very long. As you move ahead there is a bow-wave of sand moving upwards in front of the tire. If you measure your contact patch in the sand it might be 12-15". When you cut that in half to get the centerline it may be well beyond the rake line making the bike have negative trail. Negative trail means the fork is is trying to turn 180 degrees or reverse direction. That is why the steering goes wobbly in sand and you have to keep forcing the bars straight.

This happens in dirt also to a lesser degree, but if you run your front wheel up an incline or bump there will be a point where the wheel is "cupped" into the bump. In other words, the back half of the contact patch is on the flat and very short, but the front part of the contact patch is running up the incline and very long. The steeper the bump or incline the less trail you have. So, the trail varies wildly in loose and bumpy surface conditions.

The solo position could be a simple mistake or the rider might feel that the stronger self centering is better than the lack of turning ease because the speeds are slow and he can use the throttle and sidecar momentum to steer left and right (along with some muscles).

David
 

deejay499

Well Known and Active Website User
VOC Member
I did wonder if it was something like that, and guessed it could be better over the rocks and bumps.
 

vibrac

Well Known and Active Website User
VOC Member
Ah David! not a lot of chance for sand in UK trails I know when I went for a solo trail ride in Michigan I found lots of sand (in the woods!)and I was quite lost now give me some mud and I am happy
As to forks I ran the Comet outfit with sidecar eccentrics and never found it a problem mind you all the sections on the MCC trails are up hill and of necessity a long slog my proven technique was to hit it as fast as we could in as high a gear as it would take and reluctantly sacrifice a gear after gear down as the accent speed slowed the accent. running the rear at about 10psi we usually got there, of course they sometimes have a fiendish restart on the hill trick there is to slew the outfit at an angle in the restart box (if possible) to reduce the incline for the first foot or so. my biggest problem was lack of folding RH footrest as the ruts thrust me into the banks
 

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