[framesti]

What differences? Would stiffness be different? Are chainrings same?

 

[rfrancisco]

The R600 has solid crank arms while the 6700 has hollow crank arms,also the 6700 has the Hollow-glide chain ring, and the R600 is a compact crank, the 6750 is the Ultegra compact model. Check out this website : http://www.bikepedia.com/PA/Item.aspx?itemid=798871 and :http://www.bikepedia.com/PA/Item.aspx?itemid=114342 I got the 6750 great for thrSF bay area rides'
Good luck

 

[framesti]

shimano compact chainring

What differences? Would stiffness be different? Are chainrings same?

Is Shimano's 6750 chainrings stiffer than r600? Can they be fitted to r600?

 

[rfrancisco]

No,the 6750 large ring will only fit on the Ultegra compact crank arms, the chain rings are lighter and stiffer, I have not felt or see any flexing with this crank set. Also check out Shimano tech site : http://techdocs.shimano.com/techdocs/index.jsp for more info.

 

[jetdog9]

OK I know I've posted this before, sorry, but also an option you might find for cheap is the Ultegra SL compact FC-6650-G since it's been replaced by the 6750. The one on my bike seems to work just dandy.

 

[blbike]

Stiffness, aesthetics, price, 6700/6750 hollow chainrings (much different). R600 is about the 4th tier crankset, while 6700 just below Dura Ace.

 

[BMC Lover]

I have 13 bikes with all the set ups.
For the record the R600 may be on paper the 4th tier crank BUT it does not drop chains!
Ultegra compacts do!
In racing this is a vital improvement.
IMHO it is the most under rated crankset on the market.
Only marginally heavier too than Ultegra 87 grms!

 

[GaRandonee]

The bike I ordered had a picture with a 105, but the verbal discription said R600. I called Jenson 4 times to ask about this. Each time I was told it came with 105. Not true! It came R600. I called Shimano, and they said the R600 is "between a 105 and Ultegra". They also said the R-600 is not the same material, finish, nor is it listed as "Hollowtech II".
The ramping and pinning are the same.

 

[Jay Strongbow]

I have 13 bikes with all the set ups.
For the record the R600 may be on paper the 4th tier crank BUT it does not drop chains!
Ultegra compacts do!In racing this is a vital improvement.
IMHO it is the most under rated crankset on the market.
Only marginally heavier too than Ultegra 87 grms!

I'd say you have a set up issue you might want to look into. I ride rolling hills so I'm shifting up there all the time and have never dropped a chain on an ultegra compact.