Sprocket Covers and Entrapment

[Graeme M]

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...

[Freakshow]

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.

[jimg1au]

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

[IT400C]

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...

[supersenior 50]

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.

[firko]

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.

[Tossa]

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

[Graeme M]

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.

[jimg1au]

this works but make sure they are tight





al up i thing it cost 10.00 total and i have more chopping board to make others
jim

[pancho]

 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.

[Tossa]

thanks Jim and Pancho, given me the idea

cheers, Barry

[DJRacing]

You guys and your spocket covers                                  
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        
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"        

Nah, you guys are just taking the piss and winding us kiwi's up with this one aint ya        

[micks]

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

[Ted]

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

[reg]

  that has just made my day Ted, your a forking genius