Needing help with new chain rings for Dura-Ace 7900

[bam bam]

Hi Guys,

I am looking for some help in regards to finding some new replacement chain rings for my road bike to get it active again hopefully in time for the Cervelo Masters this weekend coming.

I badly bent my 39 Shimano 7900 Dura-Ace chain ring during a HVV race and (also the 53 to a minor extent) plus popped the two chain ring bolts.

I am looking to move up to the 54T/42? setup in the same chain ring style (bike is full groupset of 7900 Dura-Ace). This is as good a time as any as find the 53 is not enough for breakaways or down the back straight with a good wind in the group.

The bike is in for servicing but the shop has no spare chain rings and they also phoned Shimano looking for some new ones. Shimano stated they are not bringing any into Australia in the foreseeable future if at all. I have looked on appropriate websites etc but have been unable to locate any replacements.

Can anyone offer any help or direction in aiding me in my needs? Is there any other options available for me to obtain the larger chain ring setup?

Thank you for your help.

Kind regards,
BamBam.

[hilljockey]

You must ride A grade, yes?

60 k/hr with 53x12 is about a cadence of 100 (http://www.velominati.com/blog/about/cadence-calculator/).

Use an 11T and the cadence is only 94.

Maybe an 11 at the back would be an option?

Or, considering the 12 again, a cadence of 112 gets you 65k and 120 gets you 70k.  Would these speeds be enough?  It would win C grade 

[bam bam]

Hi hilljockey,

No mate, just a bunter trying to get around the course. Already have the 11T at the back. Any slight downhills with my extra (way too much) weight pushes me right over my cadence limit. I have trouble sustaining over 100 as trained too long in 70-95's and my fat thighs can't get the 110+ working yet. Trying to get this up though but looking for the 54T to see what occurs. 55T are comfortable on TT bikes using an 11 also, hence wanting to try the 54T.

Thank you for the good information and direction though. Any other options available by utilising another brands chain rings that will mix in without any adverse trouble?

Cheers.

[hilljockey]

Sorry bb, mix and match of parts is bike shop stuff that I know little about.

Regards cadence, have you considered the velodrome?  It's an excellent way to improve bike skills and fitness. A friendly crowd run it, its good fun.

[simply red]

Yes I think hilljockey has the answer for you ,Although I still can t figure out how you you bent your chain ring.Were  you in the crash  on monday or did your chainring get ran over by a truck.There is really no answer for you other than learning to cadence higher or since you have as you stated fat thighs go and ask dougie hunt how you turn them into speed machines I think its called lethal weapons.Unless your racing major hills for downhill speed and as we all know the cervelo  race at the gang as NOhills. If you can pull that 11 chainring over the hill and round the bend you will have left every one behind...although if it happens that you are racing A grade  if you see mr douglas hunt on your wheel ...your in trouble mate   even an11/55 wouldn t help ,just go enjoy racing  have fun  and don t take it to seriously its only a bike race........hopefully this advice comes in handy from a simple but red d grader

[hilljockey]

A simple but red D grader who put in a pretty good finish on Monday only getting pipped by a real good rider making a comeback.  Well done Red!

When is the big bloke coming back?  Fish can't be biting that well!

[simply red]

hey hill jockey ,hitting 47 on monday and thats my  new age ,doesn t make me go faster ,my fellow compatriot was to fast ,I couldn lead her out any longer (possibly 400m ) how do I out do that, had to ....Karen webb would  have eaten us both for lunch if we didn t get our arse in gear  ...and 13 years younger than me ....oh well thats cycling, happy to see her win.As for the big guy,your wrong ...tooo...many fish tooo much money tooo lose ... no cycling he leaves that up to me ....someone has to make the money ..and when he comes back you know how it will be ..it will be me doing all the training and he ll come back and do my butt in the sprint ...easily.WHY ALL THE TRAINING FOR THAT ..and then I have to live with it  ...

[hilljockey]

Ha ha, bragging rights at home.  Too funny.

We have that here too and I don't win that one often.

[hilljockey]

Hey Bam Bam, did you get your chain ring issue sorted?

What did you do?

What are the bits/brands that can be mixed and matched?