OzVMX Forum

Clubroom => Competition => Topic started by: Graeme M on May 03, 2012, 10:43:42 pm

Title: Sprocket Covers and Entrapment
Post by: Graeme M on May 03, 2012, 10:43:42 pm
The discussion regarding sprocket covers on the Nationals Race Sec Update thread has had a good outcome with MA offering an exemption from the relevant rule for the purposes of the Classic MX Championships. However this does not clarify the position at all, as the rule must still apply to the Post Classic MX Championships, the Classic DT Championships, and the running of any Classic MX machine at any Classic or Modern MX or DT meeting.

It is my view that all riders wishing to race their classic dirtbike at any other MX, DT or Classic MX/DT event MUST have a guard constructed of suitable material placed in such a way as to prevent trapping between the lower chain run and the rear sprocket. Club scrutineers are therefore quite correct to fail a motorcycle that does not meet this requirement. I look forward to further enlightenment from MA in this respect.

I must say I find the disinclination of riders to conform as quite strange. Most of you would think nothing of spending the money to ensure your bike has good tyres or fresh chain and sprockets yet you don't want to go to the effort of adapting a modern chain guide to fit your vintage bike. I'd imagine a couple of tabs on the swingarm and the guide from a modern MX bike would do the job nicely. How hard would it be to throw one of these on?

http://www.ebay.com.au/itm/Pitster-Pro-Chain-Guide-Kustom-Minis-Dhz-Pit-Bike-Thumpstar-Pitster-pro-/320892130184?pt=AU_Motorcycle_Parts_Accessories&hash=item4ab6a95388#ht_551wt_1163

http://www.ebay.com.au/itm/Pit-bike-thumpstar-trail-pro-Alloy-Blue-Chain-Guide-/220869667186?pt=AU_Motorcycle_Parts_Accessories&hash=item336cdba972#ht_500wt_1180

http://www.ebay.com.au/itm/ALLOY-CHAIN-GUIDE-GOLD-125cc-140cc-DIRT-BIKE-PIT-BIKE-THUMPSTER-/250984944874?pt=AU_Motorcycle_Parts_Accessories&hash=item3a6fde54ea#ht_1951wt_1163

$30 and you're done...
Title: Re: Sprocket Covers and Entrapment
Post by: Freakshow on May 03, 2012, 11:18:30 pm
not that hard on a Dt1, but i have a lot of trepadation on welding anything on my YZA frames to hang a $20 cover on .... based if only on the fact i think its not a just rulling vs the actual risk............ just saying.
Title: Re: Sprocket Covers and Entrapment
Post by: jimg1au on May 04, 2012, 05:36:29 am
i have a sprocket cover on my staracer flattracker and didnt weld a thing just use the brain god gave you and make a band that fits around the swing arm its not that hard
jim
Title: Re: Sprocket Covers and Entrapment
Post by: IT400C on May 04, 2012, 09:58:31 am
Now I admit, I only heard of this for the first time on this forum in the last few days, and I may be misreading it entirely..  I apologise in advance if I am.

I'm sorry, but this whole rule strikes me as a bit of a waste of time...   Seems like someone's got a bee in their bonnet (maybe after an initial incident) and decided that "something had to be done!"...

Most modern bike chain guides do go back to the sprocket (depending on your gearing/rear sprocket size of course), but it wasn't done as a safety measure on MX/Enduro bikes..  It was done so that a solid whack to the chain guide would be less likely to bend the chain guide brackets (the guide's partially supported by the rear sprocket in this case), and hence less chance of chain derailments....  i.e. it was done for reliability reasons..

So we all go and fit chain guides to our VMX/Vinduro bikes - if you're willing to of course...

What happens then when someone sticks their fingers down towards the end of the swingarm - instead of a crushed finger, the finger gets pulled down to the chain guard/guide, at which point it can travel no further and then the finger gets buzz-sawn off by the still spinning sprocket teeth...

So the chioce looks like a crushed finger without the guide/guard, or sawn off finger with....

Personally, if that's what we have to do to our old bikes to race VMX this year, I doubt I'll bother..  I'm not interested in welding brackets to my swingarm, and as the swingarm's a round section, I doubt any clamped on mounting system is going to be a viable long term solution...
Title: Re: Sprocket Covers and Entrapment
Post by: supersenior 50 on May 04, 2012, 10:31:34 am
While I dont profess to knowing all the history of rear sproket amputations, the only such incident I ever heard of was when Darryl Beattie lost toes on a 500 and adopted the slogan "hangin' five in 95"
Incidently, when I wrote to MQ/MA yesterday I included the Post Classic and Classic Dirt Track events as being affected by the outcome. We should await MA's written response before turning this into another gabfest.
Title: Re: Sprocket Covers and Entrapment
Post by: firko on May 04, 2012, 11:44:00 am
Quote
i have a lot of trepadation on welding anything on my YZA frames to hang a $20 cover on
My frames are nickel plated so I'm a bit hesitant to weld a bracket to mount a guard on my swingarms as well. They enforced this rule at the recent Nepean dirt track and it was interesting to see some of the innovation used in complying with the rule. I saw a lot of bits of plastic held on with cable ties but Jim's simple method method looked OK. Post a photo Jim.

This rule appears to be another dumb insurance company driven exercise in protecting us from ourselves. I've been in this sport since the sixties and the only damage I've seen from fingers or toes getting caught in the rear sprocket occurred when a punter lost the tops of a couple of fingers while helping Bob Vourmard load a CZ onto a trailer by picking the bike up by grabbing the sprocket at Ravo back in the mid 90's.
Title: Re: Sprocket Covers and Entrapment
Post by: Tossa on May 04, 2012, 12:18:49 pm
i have a sprocket cover on my staracer flattracker and didnt weld a thing just use the brain god gave you and make a band that fits around the swing arm its not that hard
jim

I'm with Firko any chance of a photo, oh wise one!!lol

Barry
Title: Re: Sprocket Covers and Entrapment
Post by: Graeme M on May 04, 2012, 12:47:41 pm
I agree with most that this seems a dumb rule. Geez, dirtbikes ARE dangerous in that respect what with spinning wheels, buzzsaw tyres, chains and sprockets, and all manner of sharp bits.

But, this rule is being enforced locally and I don't think most are aware of it. It's especially important to get it sorted before the various national titles as I just can't see how a scrutineer could ignore it.

I also think the discussion yesterday shows that even experienced officials are not agreed on what the rules mean. I will be very surprised if my reading of it is incorrect - in another life my job was interpreting legislation to derive policy positions in respect to appeals hearings, and I think I have a fair eye for the intent and spirit of legislation. In this case, the intent and spirit is pretty damn clear.

I hope by way of this "gabfest" to make the formal position on this rule as it applies to VMX and VDT crystal clear and to promote any discussion needed to ensure all are aware BEFORE they travel to distant events. If it is possible to have the rule rescinded or modified to suit vintage, all the better. But the ideal will be an agreed position consistently enforced at all levels of competition so we have a level playing field for all.

Title: Re: Sprocket Covers and Entrapment
Post by: jimg1au on May 04, 2012, 02:19:22 pm
this works but make sure they are tight

(http://i414.photobucket.com/albums/pp221/jimg1au/2012-03-21_11-39-28_973.jpg)

(http://i414.photobucket.com/albums/pp221/jimg1au/2012-03-21_11-38-12_476.jpg)

al up i thing it cost 10.00 total and i have more chopping board to make others
jim
Title: Re: Sprocket Covers and Entrapment
Post by: pancho on May 04, 2012, 04:59:07 pm
 I made one for my slider-cost $20 for a piece of thick clear plastic, plus a couple of nuts and bolts out of my assorted junk.
 One for my RT1 cost nix for a piece of sheet aluminium offcut, [it was a bit thin so I formed a lip about 10mm around the leading edge.] It's mounted with two nuts and bolts which hold the orignal chain guide.  Cost --nix.
 My bikes aren't show pieces but no irreversible damage was incurred anyhow.
 Means no hastles with machine examiners and I might add no unfortunate person is likely to loose body parts in some incident with my sprockets.
 By the way, thanks Jim for the piece of foam which you supplied and insisted that I mount on top of the handlebars on my slider which I considered unnecessary.- In my first ride of the day I got the jump out the gate only to my surprise about 20 feet out it reached for the sky so quick I headbutted the top of the forks!  So there ya go!
cheers pancho.
Title: Re: Sprocket Covers and Entrapment
Post by: Tossa on May 04, 2012, 05:44:20 pm
thanks Jim and Pancho, given me the idea

cheers, Barry
Title: Re: Sprocket Covers and Entrapment
Post by: DJRacing on May 04, 2012, 05:47:08 pm
You guys and your spocket covers  :)  :D  ;D  ;D  ;D  ;D  ;D  ;D  ;D  ;D  ;D  ;D  ;D  ;D  ;D  ;D  ;D
you better start buying up non-heat transferable exhaust wrap or at least stickers saying,
 "Hot Surface- Do Not Touch " and maybe you better make it compulsory to have rubber covers for the clutch and front brake levers so you don't pinch your fingers between the lever and pivot  ;)  :D  ;D  ;D
Maybe remove your number from your front number board and replace it with a warning that "It is dangerous to stand in front of Motorbikes"  ;D  ;D  ;D  ;D

Nah, you guys are just taking the piss and winding us kiwi's up with this one aint ya  ;D  ;D  ;D  :-*
Title: Re: Sprocket Covers and Entrapment
Post by: micks on May 04, 2012, 05:48:08 pm
got to laugh MA the controlling body that writes the rules cannot interpret them theirself. i am with graeme and montynut (re national race sec update) in how you would read the rules.
Ross Martin was an asset to MA, have they found a suitable replace yet?
Jim it`s that simple all you need now is to sell that space to a sponsor. DID, Regina maybe Renthal
Title: Re: Sprocket Covers and Entrapment
Post by: Ted on May 04, 2012, 06:13:13 pm
After you fit chain guide to bike be careful to leave sufficent room on swingarm to accomodate MA Rulebook Page 26 Section 27 Clause 3 Paragraph 4 Item 6: A clothespeg is to be affixed to swingarm encompassing a sturdy piece of cardboard which must protrude 22mm to the inside of the outer edge of the wheel spokes so as to create sufficent noise to warn of approaching machine. No shit
Title: Re: Sprocket Covers and Entrapment
Post by: reg on May 04, 2012, 06:20:24 pm
 ;D ;D ;D ;D that has just made my day Ted, your a forking genius  ;D ;D ;D
Title: Re: Sprocket Covers and Entrapment
Post by: DJRacing on May 04, 2012, 06:25:24 pm
After you fit chain guide to bike be careful to leave sufficent room on swingarm to accomodate MA Rulebook Page 26 Section 27 Clause 3 Paragraph 4 Item 6: A clothespeg is to be affixed to swingarm encompassing a sturdy piece of cardboard which must protrude 22mm to the inside of the outer edge of the wheel spokes so as to create sufficent noise to warn of approaching machine. No shit

Classic  ;D  ;D  ;D
Title: Re: Sprocket Covers and Entrapment
Post by: Snowy 76 on May 04, 2012, 06:38:53 pm
You Crack me up Dude  ;D ;D
Title: Re: Sprocket Covers and Entrapment
Post by: micks on May 04, 2012, 07:02:59 pm
ted you forgot that it must not interfere with the valve cap as it may loosen the valve cap. 
Title: Re: Sprocket Covers and Entrapment
Post by: Ted on May 04, 2012, 07:14:56 pm
Mick Mick Mick...you`re not too bright are you.  Just fit a front rim to the rear and bobs your uncle. The rules are the rules
Title: Re: Sprocket Covers and Entrapment
Post by: huskibul on May 04, 2012, 07:16:23 pm
   Yeah you wouldnt want that valvecap bouncing down the track behind you and going up someones nostril !    ::)
Title: Re: Sprocket Covers and Entrapment
Post by: mick25 on May 04, 2012, 07:33:09 pm
And we need one of those old school push bike horns :D the ones with the black rubber squeezy end   ::) honk honk when passing other riders (warning)
Title: Re: Sprocket Covers and Entrapment
Post by: Graeme M on May 04, 2012, 08:40:37 pm
Can't I just purse my lips and blow out really loudly and save the money for a chain guard?
Title: Re: Sprocket Covers and Entrapment
Post by: Doggy Digger on May 05, 2012, 02:47:12 am
(http://i1043.photobucket.com/albums/b431/DoggyDigger/finger.jpg)

 :)
Title: Re: Sprocket Covers and Entrapment
Post by: pancho on May 05, 2012, 09:32:06 am
    New shopping list
 1/ super glue for valve caps.
 2/ clothes peg and 'joker' playing card.
 3/ bicycle bulb horn.
 4/ various warning stickers.
   Now where is that Ballards catalogue!
 pancho.
Title: Re: Sprocket Covers and Entrapment
Post by: mick25 on May 05, 2012, 09:35:25 am
Thats Nasty digger
 there lots of builders out there with stumpey fingers as well. guards a there for a reason ,
I made guards for my bikes soon as i herd the rumours ,
when you think about it ,if you come off and your bike is laying there reving it horses off ::) it wouldnt take much to fall or drop your fingers in the rear cog
Title: Re: Sprocket Covers and Entrapment
Post by: matcho mick on May 05, 2012, 09:38:15 am
whats the saying?,'every pictures wortha thousand words',message received doggy!, :P
Title: Re: Sprocket Covers and Entrapment
Post by: jimg1au on May 05, 2012, 09:48:13 am
micks 25
i also fit a speedway cut out so if or when you cume off the motor will stop.
jim
Title: Re: Sprocket Covers and Entrapment
Post by: pancho on May 05, 2012, 09:56:30 am
 Me to on my slider Jim, since it first did a start line mono couple of years ago!
Title: Re: Sprocket Covers and Entrapment
Post by: mick25 on May 05, 2012, 09:58:04 am
JIM   I did think of one of those speed way cut off switches a while back good point.
but I did wounder what others throught  ???  a bit off over kill  :-\   :-\but safety first hey
Title: Re: Sprocket Covers and Entrapment
Post by: mustanggrahame on May 05, 2012, 09:59:53 am
What about a cover for the whole back wheel? If the sprocket is spinning around then the wheel must be as well!
I think this racing thing is all too dangerous. Why don't we bring our bikes to the track, look at them all, maybe start them up (if we can work out a perfectly safe way to do this) and decide who gets the trophies, by reading old magazine comparos. Eg Pre 85 500cc, CR Honda the best on tight tracks, so obviously only those who turned up with a CR can possibly win. If more than one person brought a CR then some more investigation is required. Maybe someone had their front tyre at 25psi, or someone else had an Ohlins shock, etc. A well set up KX may be able to sneak into a place under this scenario.
This shouldn't be too hard and much safer than the current situation of actually racing our bikes. Our bikes wont deteriorate or get dirty. Our fitness wont matter. Young people wont win just because they are better riders.
Cheers, Grahame
Title: Re: Sprocket Covers and Entrapment
Post by: maico police on May 05, 2012, 10:23:55 am
What about a cover for the whole back wheel? If the sprocket is spinning around then the wheel must be as well!
I think this racing thing is all too dangerous. Why don't we bring our bikes to the track, look at them all, maybe start them up (if we can work out a perfectly safe way to do this) and decide who gets the trophies, by reading old magazine comparos. Eg Pre 85 500cc, CR Honda the best on tight tracks, so obviously only those who turned up with a CR can possibly win. If more than one person brought a CR then some more investigation is required. Maybe someone had their front tyre at 25psi, or someone else had an Ohlins shock, etc. A well set up KX may be able to sneak into a place under this scenario.
This shouldn't be too hard and much safer than the current situation of actually racing our bikes. Our bikes wont deteriorate or get dirty. Our fitness wont matter. Young people wont win just because they are better riders.
Cheers, Grahame


Even simpler would be to do our racing over the internet. Hang on......
Some people do. :D
Title: Re: Sprocket Covers and Entrapment
Post by: Freakshow on May 05, 2012, 01:14:15 pm
i doubt those flexible covers would comply anyway ? it would have to be at least a 5mm fiberglass or similar. 

As any thing like in the photo would not stop fingers being pulled down the chain and guided into the sprocket, or if it was over it would defect you into it anyway.  Thats all smoke a mirrors and kinda pointless exercise. 

Its not a serious solution if its a genuine problem.
Title: Re: Sprocket Covers and Entrapment
Post by: micks on May 05, 2012, 08:19:56 pm
ted u r rite aboot bening knot 2 brite.
the rules don`t state witch side of the swingarm the the cardbroad should be arfixed 2 if it is the rite hand and interfears wif the valve cap it  in the forward motionson could loosen the valve cap and get trapped between the chain and sprocket.     
Title: Re: Sprocket Covers and Entrapment
Post by: vmxrider on July 08, 2012, 06:05:11 pm
Haven't raced or been through scrutineering since this rule has come up, whats the latest, is it being enforced?
Title: Re: Sprocket Covers and Entrapment
Post by: Mick D on July 08, 2012, 06:11:57 pm
ted u r rite aboot bening knot 2 brite.
the rules don`t state witch side of the swingarm the the cardbroad should be arfixed 2 if it is the rite hand and interfears wif the valve cap it  in the forward motionson could loosen the valve cap and get trapped between the chain and sprocket.     

At last, finally a bit of common sense amongst us. Hail the new Messiah :D
Title: Re: Sprocket Covers and Entrapment
Post by: matcho mick on July 08, 2012, 11:36:02 pm
Haven't raced or been through scrutineering since this rule has come up, whats the latest, is it being enforced?
yep,sure is,i just remembered i havn't done the ossa yet! oops  ::), :P
Title: Re: Sprocket Covers and Entrapment
Post by: jimg1au on September 10, 2012, 04:35:01 pm
BUMP
nationals coming up
Title: Re: Sprocket Covers and Entrapment
Post by: suzuki27 on September 12, 2012, 07:23:13 pm
Any word yet if it will apply at the Dt Nats?  Does the OEM chain guide on a '75 CR125 meet the requirements? How long is a piece of string? I will bring extra hose clamps,hacksaw and bolts and if someone can bring a nylon cutting board we should be right!
Title: Re: Sprocket Covers and Entrapment
Post by: jimg1au on September 12, 2012, 08:34:56 pm
got my cutting boards from the supermarket kitchen dept
Title: Re: Sprocket Covers and Entrapment
Post by: suzuki27 on September 13, 2012, 05:52:20 pm
Sweet.