After the experience of cramping going up Snowbird at the end of the 1000 Warriors race, I decided to order a new compact crank.  I had already put a SRAM 11-28 cassette on the rear and that was working, so I would be able to still get a fairly high gear (50/11) with a compact crank.  I was lucky because Performance had it on sale for almost 40% off retail and then there was a 12 hour extra 20% off coupon.  I bought it and a new XTR deraulier for Ann’s bike and had them delivered to our Utah home so no sales tax.

I decided to do the swap today. I first removed the existing Dura-Ace double crank by looseing the two bolts using an allen wrench.  I then removed the cap using a special Park tool.  You then flip up the plastic tab that keeps the crank from coming off, then pull off the fright crank arm.  I could see that I had a press fit bottom bracket that came with the new frame.  Since this was brand new, there was no reason to replace it.  I pulled the crank assemble out of the bottom bracket and reversed the procedure.  I could not get the plastic lock stop to engage properly so I thought maybe my crank arm was no in all the way.  Finally I swapped the plastic tab with the one from my double crank and it worked just fine.

I had to move the front derailuer down a bit but my new frame has a clamp-on type so that was easy enough to do.  My frame that ended up breaking had a brazed on derailleur and I was always worried about the amount of adjustment.

I realized I also need to also shorten the chain.  The prior chrankset was 53/39 and the new compact is 50/34.  So the large chainring has 3 teeth less and the small chainring has 5 teeth less.  The chain goes around slightly more than 50% of the chainring,  So for the large chainring that means 3 * .5 = 1.5 links and with the small chaingring 5*.05= 2.5 links.  You can only remove links in multiple of two so I took out two links and checked the chain when it was cross chained in both directions.

So how much lower gear will I get?  The compact crank with a 11/28 cassette gives you the range of a stock triple since 53/12 is about the same as 50/11 on the high end and 34/28 is about the same as 30/25 on the low end.  Of course it will not be as low a gear as a triple with a 27 or 28 tooth cassette.

My next project is to add mountain bike gearing to Anne’s single bike.  On the same order with the Dura-Ace compact crank, I ordered a Shimano XTR rear derailleur that was also on sale.  But she has 10 speed shifters and most mountain bike cassettes are 9 speed.  I had to either get a special 3rd party 10 speed cassette or try a device that changes the cable pull.  I decided to try the later.  But that is the subject for another blog entry.

Categories: Cycling Equipment
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