A Bantam for BEARS?

Just been thinking about making a Bantam to use in the BHR BEARS Championship.

Reason why - that class is in its infancy and is attracting a lot of publicity. (Old Bike Mart,
Classic Racer mag etc and is being very much pushed by BHR and VMCC. I'm thinking a
fast Bantam(in BEARS) may attract more people to race a Bantam.
Years ago my Giant killing of bigger bikes in the Champion of Champions seris definately
got the Bantam noticed! (Articles in OBM CR)
ie you didn't need a £25K Manx to become the club champion - just a £2K Bantam.

A Bantam would look good with Dymag or Astralite wheels and other up dates...

Anyone else had any thoughts??

Not sure what the rules are for bears but a dymag wheeled bantam would be very cool could u use a side c/c/ reed bantam engine ????

there have been many specials and Bantams with cast spoke wheels in the early 80's so this is not new but astralite's would look the dog'd tagums,

on the cc side mounted reed this is well within the current Formula Rule Ii seen this already but with an unusual Crank

Bur why build a Bantam why not just build a special and call it a Bantam like the Tomic "what a cracker that was".

regards

Derek

I'd like to see '3 spoke Dymags in Black' !
But definately needs to be a 'Bantam' not a special.
Not going to encourage anyone to race a Bantam
if your racing something which is not recognisable as
a 'Bantam'
If found the Todd-Amos 186 would be a good choice-
very much a 'bantam' but not within bantam rules.

I won't be surprised if Rob's not making one as I type...

All bar one of the 186cc Bantams went to Harrold white, in the southern hemispher.

I can not see how the engine or top-end does not conform to current 175cc/190cc rules as they clearly say, original's GEORGE Todd or copies acceptable, but I do agree and understand there are to many gears and the frames would not conform. as it has 5gears and two smaller front down tubes like a cradle.

regards Derek

Yes too many gears 4 and not std 58mm Stroke - as stated in the rules but a great BEARS base!!

Hi Mike :-
you need to have a conversation with George he is starting to remeber all kinds of stuff he had forgotten, you could ask George about the 186cc, but not all stroke's were the same, I have the micro Film's to prove, they were made at 58mm / 62.0mm and 64.0mm stroke, I believe the 58mm stroke items were produced first, primarily for the trials team, and whentto onslow and Herman Mier, for the scotsh 6 day trial team.
this is the barrelswe use but the corsand outter fin sections are allthe same. as they used the main std core boxes, information is unfolding all the time about, George's design, but they all used the same core boxes Old man onslow new this he had the coreboxes, actually there was differnt cores to the trials items but the basic inner central core was the same for all the patterns, other than the transfers and exhaust outter stub section, some had two transfers others had "four".

regards Derek

Re - Mag wheels. Many moons ago our team looked into the possibility of using mag wheels but found that many of the easier obtainable production wheels weren't genuine magnesium and weighed more than alloy rim spoke wheels.

I think you will find the Tomic was not a Bantam, but the saveit was Bantam based.On a slighty diferent note the other day I was discusing gearboxes with a man that has done a lot of work on Bantam 3 speed boxes. He tells me that you could make 18 diferent gear ratios with standard Bantam gears that would all be leagle in the fomular. They would not all be of use to a road racer but it is posible.

ratio's Ted !!!


Derek

You are quite right Ted the Tomic was not a Bantam - it was the creation of one mans imagination
using Yam YZ 250 crankcases/gearbox. Interestingly it had a 58mm stroke! but a 66mm bore.

Thats the point Ted - A fast bantam in a bantam race impresses the limited folk watching, however
a fast bantam racing out of class say BEARS could well be the first 2-stroke home and impress a
different audiance who wouldn't go and watch a 'Bantam Race'. A special that is not a bantam is
not relevent? I've raced my bantam to championship success in 125 open class(BRC) and C of C(BHR).

A bantam mixing it, out of class can impress!!

Robbie are you building one after your win at the Thundersprint.

Well Done Rob your (out of class) victory also impress' and new audience!

Yes but a Bantam covered in a fancy skirt can never be appreciated as a BANTAM!! Riding a naked Bantam in BEARs would be something else!!

It´s like putting a Scots Piper in baggy trousers and telling the audience HE REALLY is Scottish!

Cheers!

Hi Derek you just have to read the rules if it dose not say you can't, then you can! In all forms of racing there are people who think within the rules and others that copy what has been proven.
Also your coments on the Ned head show a great deal of not thinking, just because somthing looks good or bad is on reason to asume it's worth.

Hi Ted hope your feeling ok,
"why dont you come and have a cup of tea with me and Dad - we are at Cadwell.

kind regards Derek

Derek ref gears you can use any combination of BSA- BRC- Snell Bantam gears 3 speed.
I feel the only ones worth using are C.R. '1st pair' 19/28 plus '2nd pair'22/25 but 26/21 ,
25/22 , 24/23 output pair depending on your requirements. A BTW or TOM modified G/box
uses std road gears to make a CR box of :- 1 -19/28 2-22/25 3- 24/23

I feel gear ratio's are something you cannot work out with a pencil and a piece of paper -
its something you just have to try at each and every circuit to find out what works best!

Happy gearbox testing?? Mike

Thank you Michael -

one question, ! on the top gear ratios, do you mean 23/24 or 24/23 snell

got this from "alf snell" ?

I think he made / supplied George Todd ? - as they are listed ch001 and che003 in Georges parts sales list for sale in may 1972, George sold
two gear boxes,
choo1 = a close ration box
choo3 =an ultra close ratio Box,

Ed has just recieved these drawings from George Todd.

Kind regards "Derek"

Hi Derek - An ultra CR box - why have you been keeping this information a secret from
the rest of us! Tut tut not very sporting of you! Hardly in the spirit of bantam racing!!

Ref my previous post re:- gears should also of said 'and copies of BSA/BRC/Snell bantam gears'

I think everybody else knows what is happening in bantam gearbox mod's etc , its just nobody tells you!
Possible they are scared you might want to ban stuff?

How about getting some UCR boxes made Derek ??

Kindest regards Mike

P.S. I know who is riding my bike at Cadwell! Who's riding your wheel?

History well tell.

regarsd Derek

Derek i feel you are wrong in every aspect of your post!

I haven't sent you a p.m. ? - I believe you are on another planet!!

I also think your posts are still upsetting folk - and they need to be less
confrontional. 'Calm down dear'

My bantam will be at Cadwell as a static display bike.

I assume jugding from your recent 'no shows' we won't see you at Cadwell!?

Oh... last bantam race I won was the last bantam race I entered - Sept 2011

See you at Snett... maybe ??

Cheers Mike

Hi Mike

The last post contains chosen words, "so I will bow out, but after I have posted the the details bugging me" so you can see specifically why I keep asking the same questions.

i will try and get these loaded today Ihave some one looking at helping me getting the info loaded, so you can discuss what I have been winging on about rather than !!

upsetting people its certainly not my intention, but I want the facts and feel the truth will come outno matter if Im barking upthe wrong tree I am man enoughtodothe right thing butI want to be sure. !

or is your reply, you looking for an excuse not to have to get your wallet out at the bar, you could always buy a bear for those that are going to cadwell.

How did you know i was unable to make Cadwell, only my secretary knows this. !

Derek Betts

Aaaah Cadwell! Mike! you must stop being nasty to our Derek he is tutoring me free of charge. Perhaps he´ll get round to telling me about how many flywheels he has on his Bantam?

I have to say this as shouldn´t --(being under the tuition of Derek) -- it was at that wonderful Louth circuit that I won my first Novice road race. See the Avatar there -- on a naked Bantam costing 40pounds stirling to manufacture, CR gears costing all of 4 quid, pukkha Bantam forks and long-stroke motor revving at 8,400 rpm (with wind behind) -- that pic in 1968 (or was it 1969??) -- wearing nano-thin leathers patched with black plastic tape, as were the shredded boots (that the scrutineer fowned upon severely) rounding Mansfield for the last time screaming hysterically with joy, "I have won ...!" -- no clutch on that last lap, of course. Most of Cadwell -- for me -- was slipping and destroying clutches but oh! the joy of belting it downhill from Park to Mansfield....!!! The latter can be taken quite quickly when your brakes are almost non-existent!!

Pity you stopped reading after the first two lines Mike --`cos that was a beautiful bit of Soppy Nostalgia.

Then there was the time I took my 1927 Triumph 500cc there after putting it on 9.5:1 Compression Ratio, drilling out the main jet with an 1/8" (sorry, 3 mm) drill and running on methanol -- still hand-change (3-speed box) -- and finishing around mid-field.

Aaaaaahhh Cadwell! Gonna try and be there in September 2012....

Cheers!

Rodney Dumbcluck!

Well Derek

This is news to me. I have never heard of or ever seen an ultra close ratio Bantam gearbox and I was spares secretary for several years.

Anyway, lets assume they exist and think about their effects.

With an ultra close output pair, the rev drop from 1st to 2nd would remain unchanged but the rev drop from 2nd to top would be closer - in the region of 800 to 1000 rpm on a high revving motor - thats almost half the rev drop of a standard close set.

If the motor had maximum power at 12000 and you revved it to 12000 in 2nd you would change into top and find the motor doing 12000/1.089 = 11,019 rpm (assuming no rev drop during the gearchange) with only another 981 rpm to go to maximum power rpm. If you took advantage of some over-revving in 2nd you would be changing into top and find you are already so close to maximum power rpm there is almost no point in changing up!

No, it doesn't look like there's any advantage changing between 2nd and top but what happens in 1st gear with this ultra close ratio set? Remember this is a narrow powerband motor and by definition will not have any useful power at low rpm so do the maths and think for a moment about 1st gear.

1st would be 1.412 as against the std close 1.538 so the bike must be going 8.9% faster in 1st gear before you can get the clutch home. Remember this is a motor with a narrow powerband - how is the ultra close box going to be an advantage on slow corners or off the line?

I now understand what you wrote some time ago Quote -
the top three would fly away comming on of the corners into top gear - this actually always lead me to believe they had somthing "different" and was not telling "gearboxes top gear ratio", End Quote

There is no need to assume an "unfair technical advantage" or some special gears - its just simple physics - they have a wider powerband OR they got the power on in the corners earlier than you OR they went faster round the corner than you or quite possibly all three!

Mick

seeI new there was a simple explanation, !Ned got me thinking again then this infor turns up from George, but Im glad that all settled now,I can try and find some other reason toslow you london boys down, you probably been thinking more about this than fettling "so you should " your already to quick.

besides it certainly woke every on up,


kind regards Derek

Good grief -- didn´t any of you slip the clutch to keep your speed and revs up??

The slipping clutch acts as a torque converter (roughly 2.13:1 ratio it is...) and my fingers ached for a week after riding Icarus 1 at such circuits as Cadwell - Wow! you blokes certainly had some torquie Bantams then if you only slipped the clutch at the start!!?? From Park to Mansfield was Full Elbow (Full Throttle for Derek) and a rest for the left hand with that wonderful left hander Mansfield just before the finish....

Apologies to all you others but I just had to slobber in that bit of sloppy nostalgia.

Good old days of having a committee meeting at the Hoop & Grapes, Holborn ey Mick!?

PS -- was it The Hoop & Grapes ???

Cheers!

mjpowell wrote:

I haven't sent you a p.m. ? - I believe you are on another planet

Not really, just the one next to that one!