Installing Compact Crank

886014 said:

[font=Times New Roman]I have a Trek 2300, originally a triple, that I'm swapping components around to use as a crit bike. Hopefully that it will work ok and any crashes will save my “good” bike. I’m juggling components around and a compact Shimano R700 crank will go on this bike (not by design, just what I have). The rest is full Dura-Ace. When installing the front derailleur it won’t adjust down far enough for the usual spacing between the front derailleur and the large chain ring. It is a clamp on adaptor and I COULD just loosen it and adjust it down but wonder if this is the correct procedure ie what would one do if it was a braise on? This is the first compact I’ve fitted and can’t find anything specific on the net. Could someone who’s done this please advise? Thanks! [/font]

I would lower the FD at the clamp so that the cage swings through 1-3mm above the teeth of the big ring.

lower the band, thats what it's for.

if it was a braze on, hopefully the mount would have a slot that would let you adjust the derailleur down far enough. if not than you need to do some filing. some derailleurs like the SRAM Force/Rival actually have two mount points for the screw in the derailleur, an upper and a lower, which prevents the requirement to file. Unfortunately the Shimano stuff only has a single drilling for the screw.

--brett

Ok thanks, I'll go that. I guess what I was getting at was whether the standard 1-3mm gap may be different for the compact. Unfortunately the R700 is not part of a series and is not mentioned in any FD instructions that I've come across. I didn't want to disturb the band if I didn't need to as I guess the paint will be damaged under its original location and will damamge a new location.

As an aside, sprinting around 60kph and I normally use an 11 on the back. Any idea what cadence this would be with a compact?

886014 said:

Ok thanks, I'll go that. I guess what I was getting at was whether the standard 1-3mm gap may be different for the compact.

As an aside, sprinting around 60kph and I normally use an 11 on the back. Any idea what cadence this would be with a compact?

I would try it and see - you'll know if it works.
I get 105.6 for 50T big ring and 700Cx23mm tyre.

Hey thanks for that! Like having my own personal experts on line 🙂 Yeah 105 would be just fine, almost perfect in fact. Thanks again guys!

All cranksets require about the same tuning.

I've just put R700's on a bike I built with a SRAM Force FD. I set the gap at around 3mm or so. Shifting is perfect.

--brett

I have come at this compact crank concept from a completely different direction, short crank arms for short or disabled riders.

My source of 160mm crank arms is getting too expensive, so I found a new supplier. Not only 160mm, but also 150, 155, 165s, all doubles, no triples! However the PCD of these is 110mm, this then leads to chainring supply problems as some of the bikes are road and some are MTB.

In comes CC chainrings to the rescue from Shimano. Today I bought a pair of 50/34 9 speed and assembled the crankset, looks good, needs a short square tapered drive BB, say 110mm. I will try it on a bike next week, either a Felt F100 or a Giant CRX4 as I have clients with 160mm cranks on both.

more later...