Why micro gearing sucks for race bikes...

[kennyhunter6061]

My mate Stuart bought a race bike last year for a good price.  The bike came with good parts but the Profile hubs came with a 9T driver, not a regular race-sized cog.  He had been struggling with a too-big front ring for months so a week past Sunday he went to Evans and bought a 25t chainring to fit the Shimano Saint crankset.  He told the guys at the shop that the ring was for a bmx race bike with Saints.  Stuart immediately fitted the ring and headed to Clydebank track.  He pottered around the track a few times before giving my racing buddy Dan Kerr a go.  Dan (37) decided to do a practice gate and when the gate dropped he went flying over the bars on his first pedal, slamming hard onto the concrete start hill causing him major pain.  At first I thought the chain had come off but when Dan stopped rolling down the hill and got up it was clear what had happened.  I've run Saints for nearly 2 years with a 42T ring with no problems so this just shows what can happen if you're 37 years old and try micro gearing on your race bike.  Or maybe Dan just had too much porridge that day 

[SaMAlex]

that chainring dont look up to much, and only having 4 bolts cant be great.

[kennyhunter6061]

The ring itself is pretty thick at the bolts but Saints come with alloy bolts which can't be as strong as the usual bmx cromo/stainless ones.  I reckon one of the bolts has snapped and the ring has then done likewise.  The problem with the 4-bolt design is that if one bolt fails it makes almost 1/2 the ring unsupported, whereas with a 5-bolt design it's far less and the other bolts have a better chance of keeping it all together.

[dibly]

that guy must have some chuffing power in his legs mate

[HEYWOOD BMX]

  I sometimes run a 36/13 on my racebike and have broken a few chains off the gate.When I watch some of the local street riders come down to my track with 25/9,they seem to pedal like hell but go nowhere!

[RATTY]

Fook that, the shop would be wearing the remains of that chainring if that was me

[SaMAlex]

The ring itself is pretty thick at the bolts but Saints come with alloy bolts which can't be as strong as the usual bmx cromo/stainless ones.  I reckon one of the bolts has snapped and the ring has then done likewise.  The problem with the 4-bolt design is that if one bolt fails it makes almost 1/2 the ring unsupported, whereas with a 5-bolt design it's far less and the other bolts have a better chance of keeping it all together.

That all makes perfect sense, spot on Id say.

Good old Shimano. What do they know about BMX anymore anyway? (ooohhhhh  )

[baldbmxer]

C'mon Kenny - you should know that putting Danny Kerr on a bike is only gona end up in bent metal, ripped grips, torn skin and hurt pride  

Hope you're OK Danny, how did you explain your latest venture over the bars to the wife?  

[baldbmxer]

The ring itself is pretty thick at the bolts but Saints come with alloy bolts which can't be as strong as the usual bmx cromo/stainless ones.  I reckon one of the bolts has snapped and the ring has then done likewise.  The problem with the 4-bolt design is that if one bolt fails it makes almost 1/2 the ring unsupported, whereas with a 5-bolt design it's far less and the other bolts have a better chance of keeping it all together.

That all makes perfect sense, spot on Id say.

Good old Shimano. What do they know about BMX anymore anyway? (ooohhhhh  )

They make some spangley pedal and shoe combos 

[kennyhunter6061]

I don't think his business partner sees the funny side of all these injuries.  Literally five minutes before it happened we all said to him "Don't be going over the bars today!"    His first words after it happened were "You'll need to send a picture of that to Jonathan Hearns" 

[teamsano]

imagine how flappy that ring would be if it was the size of a 44t?

hope the dude is ok. 

[kennyhunter6061]

Don't say that gogo - I'm now running a 45/16 setup on my Saints, so I can run my lovely new graphite skyways    Just like old times eh!  Although, my 45T ring is one of the new Profile ones so hopefully a bit tougher than the Shimano jobs

[Dark Diggler]

I sometimes run a 36/13 on my racebike and have broken a few chains off the gate.When I watch some of the local street riders come down to my track with 25/9,they seem to pedal like hell but go nowhere!

25/9 gives you slightly more poke than 44/16 dude, and a smidge more than 36/13 

[80sdave]

That chainring is a TA Chinook which is a very light weight cross country chainring our mechanic uses for endurance racing toally wrong for a bmx who said that will be ok should be 

[Longun]

Got to say I don't think the problem lies in micro gearing, but in the use of a 4 bolt spider and a lightweight chainring. Can't imagine something like a Profile Imperial folding over like that.