Misc: Everything Else Series B versus Series C Machines

Nulli Secundus

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Completely agree with Glenliman, I frequently have to stand my bike up and roll off the throttle after encountering corogations on corners. We have some rough roads in NZ and losing all steering with the front wheel bouncing frantically up and down is no fun. Dangerous infact. While I want to keep my Series B with Bramptons as standard as possible I need to either slow down or buy one of those nice coil over shocks.
I have a coil over shock on my Rudge race bike and even on the relatively smooth race tracks the forks bounce up and down a lot. I have only recently found out, after receiving some advice from experienced racer Mervyn Stratford, who was watching me recently at Lydden, that reducing the front tyre pressure quite significantly and increasing the suspension friction damping, has calmed the front end down, which has made the bike more rideable. Strangely my lap times did not improve much.
 

passenger0_0

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I have a coil over shock on my Rudge race bike and even on the relatively smooth race tracks the forks bounce up and down a lot. I have only recently found out, after receiving some advice from experienced racer Mervyn Stratford, who was watching me recently at Lydden, that reducing the front tyre pressure quite significantly and increasing the suspension friction damping, has calmed the front end down, which has made the bike more rideable. Strangely my lap times did not improve much.
Now that's a thought Nulli Secundus. I currently run 32 psi in the front 20" Avon Speedmaster ribbed tyres. Maybe a bit too high. I'll try dropping it down to 30 or even lower in my next ride.
What doesn't help is the grease that's got into the side friction damper so I've got no dampening to speak of.
 

Nulli Secundus

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Now that's a thought Nulli Secundus. I currently run 32 psi in the front 20" Avon Speedmaster ribbed tyres. Maybe a bit too high. I'll try dropping it down to 30 or even lower in my next ride.
What doesn't help is the grease that's got into the side friction damper so I've got no dampening to speak of.
My Rudge is light compared to a Vincent twin. I have a narrow 21" and was using a tad over 25 psi. I dropped eventually to 21 psi. Mervyn suggested 20 psi. These figures will be much lower than what you need, so I would gradually reduce and go for a test ride, which is what I did through a series of races. Good luck.
 

Nulli Secundus

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At what point do you start to risk tyre to rim slippage, if you are not using security bolts that is.
Good point. I haven't yet measured the pressure when the tyres are hot and being race compound they warm up a fair bit, so the pressure does increase. So if I had 26 psi when cold the pressure might be over 30 when hot and that would cause the tyre to bounce significantly.
 

vibrac

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Its not just weight or tyre pressure its also wheel base and tyre size at least thats my conclusion my rigid teles trophy about the same weight as my KSS velo with girders both with single seats is much more uncomfortable.
mind you the Triumph is on knoblies that may affect things but sizes are similar
For track use we found the 18" wheels and tyres of the Comet that Ben suggested much more controllable than standard Vincent which supprised me as I always raced it with 20 & 19 and still do with the Flash
 

BigEd

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My Rudge is light compared to a Vincent twin. I have a narrow 21" and was using a tad over 25 psi. I dropped eventually to 21 psi. Mervyn suggested 20 psi. These figures will be much lower than what you need, so I would gradually reduce and go for a test ride, which is what I did through a series of races. Good luck.
When my brother John was racing my rigid Sunbeam we ran 19" wheels with Avon GP tyres with pressures at 18-19 psi, far lower than any tyre manufacturer would recommend. The friction dampers on the Druid girders were tightened so that they would only just move on a large bump. The suspension then came mostly from the tyres themselves. On most UK tracks there are not many sharp bumps. I'm not suggesting that this will work for every rigid bike but it worked for us and could be a guide for others using similar old machinery. Lots of suspension travel is great but only if you can control it with adequate (i.e. modern hydraulic technology) damping, preferably two way. I think I may have posted something similar before and although it not really specific to this "Series B Versus Series C" it bears repeating with relation to Mervy's suggestion.
 

Albervin

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Aside all the smaller changes, of which there were many, the significant change was to the suspension. And most notably the upgrade to hydraulic shock absorbers over friction dampers. This would have been the major factor in the specification from a "B" to a "C" model. As great as they are the Brampton forks were very outdated by then, and the factory would have been busy trying to improve on them, especially as most other makes were using telescopic forks. Although not as ridged and strong as the Girder forks, their action and behavior has proven itself pretty hard to beat, and still the norm to this day.
Don't forget that the change to Series C also brought rear hydraulic damping as well. Combining the two made a huge difference in handling. Now that many people (including me) have incorporated front and rear hydraulic damping on our Bs plus added the benefits of a 21" front wheel there are some Series C owners who will admit (in a quiet corner) they are superior to a C in handling.
 
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