rickrob 

A friend asked me to replace the replace the rear cassette on her Jamis Ventura road bike with one that has a much larger range so it's easier for her to climb hills.

Right now, the bike has a 9 speed Shimano 105 RD-5501 rear derailleur with what looks to be a long cage (a GS?). The rear cassette that's on there is an SRAM 12-23, and the front chain rings are a triple, with the largest having 52 teeth and the smallest having 30. I believe that gives a chain wrap of 23-12 + 52-30= 33.

The specs on the RD-5501 say that :

27 is the largest amount of teeth it can handle. Smallest is 11. Front chain ring difference is 22. Total capacity is 37 ( I assume that's chain wrap)

I figured I could get by with an 11-28 cassette and a max chain wrap of 39 and that was worth a try.

However, she wants more than that-- Something like 11-32.

I'm not real confident that the RD-5501 would even handle that cassette. That would add 10 teeth to the chain wrap making it 43 and I doubt the B screw would have anywhere near enough adjustment to even try it.

I'm thinking I need to replace the rear derailleur with a mountain bike model to get that kind of gearing. Can anyone recommend a model that would be compatible with a 9 speed cassette and the 105 shifters on this bike?

Maybe a Shimano XT M771 9 speed?

Or, does anyone have any other suggestions on how I can accomplish this?

Thanks

Andrew R Stewart 

Just about any Shimano 9 speed spec ATB will be compatible with 9 speed road shifters. We use the Deore RD-M591 as a conversion to lower gears often. You can run a 32 or 34 tooth low cog easily and even could change out the 30 tooth granny ring for a 28 with very little ft shift differences.

As compact double cranks have gotten to be the road bike standard we do this type of conversion on customers old bikes more and more often. The industry seems to forget that riders age and loose strength over time. What might have been good enough a low gear when one is 45 or 55 often isn't 10 years later. Yet in those 10 years the industry sees fit to make most low gears harder on the "trendy" compact doubles. I have been told this is driven in a cause of saving their customers from themselves, the inability to learn how to shift a ft der nicely on a triple. Andy (getting off his soapbox)

rickrob 

Thanks for the advice-- From what I can tell, the shifters appear to be 105 STI Flight Deck ST-5600. I can't find the model number on them, but they match that model from the images I looked at. If the RD-M591 will work with those, then it looks like that's the way to go.

Davet

davidad

Replace the 30 with a 24 and go from there. A 24-28 will give her a 23" low gear.

70sSanO

rickrob 

Thanks to all for the advice and suggestions-- I ordered the Deore RD-M591, an SRAM PG950 11-32 Cassette and a new KMC X.993 chain. Should make the hills a lot easier...

mawn

this worked well for you?

rickrob 

Yes, it worked well -- no issues that I can recall. My friend rode the bike with this set up until May of this year when she bought a new bike.

urbanknight

Very common on tandems of the 9s era. Those RDs can be found fairly cheap to this day and do a great job of taking up a larger cassette than the stock road one was meant to take.