Fran & Nanette
As I have posted before, we have Spec Tri-Cross bikes that serve as our go-to bikes for everything errand related and for touring. It has a 10-speed Shimano 10-speed cassette, 11-28T. We NEVER use the the 50T chainring on the Shimano 105 crankset. We'd like to change out the chainrings for something that would give a good range of gears, using all 3 chainrings, which are currently 50-39-30.
Can you recommend a readily available combination of chainrings, that would work? Something like a 46-36-26? (I have no idea if that would be good or available...)
There are mountain bike crank sets with 42/32/22 chainrings and it would probably be cheaper to change the entire crank than to buy three chainrings.
130 for the large bolt circle precludes any thing smaller than a 38t middle ring.
A 110 Crank can be bought as a way to get the 36t, middle,
the minimum is 34t then.
If you do want to just buy chainrings , QBP is a wholesale source ..
Your LBS , or several online retail+ shipping options exist.
Fran, Google "28 38 48 crankset". This is a popular treking crankset.
I was considering recommending that but if they never use the 50T ring, I didn't think a 48 would be enough different to bother with. They apparently stick with the 39 and the 30 so a 42 or 44T big ring would at least be small enough to get some use.
Originally Posted by bradtx
That combination is available. Sugino and Stronglight both make cranks with those rings with a 110/74mm BCD spider.
Originally Posted by McQz
The Impact triple comes in a few other variations like 46/34/24 and 46/36/28. You may want to spend some time comparing your current gearing and cassette cogs used with these potential new set ups to see where your common speeds will fall. I prefer to not constantly be swiitching chainrings but that's me. I prefer a 42T middle ring but you might find the 34 or 36T perfect. If you currently don't need anything lower than your 30T inner ring offers, you should probably not bother with a 24 or 26T inner ring. A 28T would be better suited.
With all that said, another potentially cheaper option for using more of your chainrings is a different cassette. A junior cassette, like the 16-27T here: http://www.universalcycles.com/shopp...8&category=359 would certainly have you using the 50T ring more (it might even be too small paired with only a 16T cog). You may or may not like the tiny gearing steps either. Perhaps then the 13/14/15-25 cassettes might be better options.
Lots to consider
Shimano made their original RSX crank and their old Deore LX MTB triple in 46/36/26 and 46/34/24 respectively with a 110/74 bcd using a square taped bottom bracket. If you can find one of these NOS they will work well.