Chain ring question

[ny biker]

The more I read and think about this, the more there is to read and think about. What's very cool is that I can go to the Bike Archive on Trek's website and get the specs for the road bike that I bought in 2003 and replaced with my current bike in 2010:

Shimano 105 52/42/30
Shimano HG-50 12-25, 9spd

So I can run those numbers through Sheldon Brown's gain ratio calculator for comparison to what I have now. The old bike had a triple, and I mostly used the middle chain ring, though I never hesitated to drop to the granny when I felt it was necessary. Before buying the new bike I made sure that the lowest gears were comparable to the old one, but now I will look more closely at how the middle ring gain ratios compare to the gears I often use now with the compact double.

In another thread we recently talked about the aging brain, and how it's harder to learn new things as we get older, except some things that really interest us seem not so hard to grasp. This is a perfect example for me -- learning more about gearing is interesting, and therefore relatively easy.

[north woods gal]

Been a re-learning experience for me, too. Actually getting hard to find a triple, these days, even on MTBs. The trend is definitely to doubles and, now, even single chainring bikes with big cassettes in the back.

[ny biker]

Still working on this. A few developments.

A friend sent me a link to an article on choosing chain rings, but I haven't had a chance to read it yet. Hoping to get to it today.

While out riding the other day I was thinking about how rarely I use the 11 cog on my cassette. So now I'm thinking the new one will be a 12/32 -- 12-13-14-15-17-19-22-25-28-32 (as compared to an 11/32 with 11-12-13-15-17-19-22-25-28-32).

But the big thing is -- the cassette currently on my bike is not actually an 11/28. I got down on my hands and knees this morning with a magnifying glass and a flashlight to look at the cassette that's now on the bike, and the cogs are labeled: 11-12-13-14-15-17??-19-21-23-26. (The 17?? is the cog that I can't see right now because the chain is in the way. Most likely it's a 17.)

The original bike specs say it came with an 11/28 -- I can find a post on this forum from when I bought the bike where I discuss the differences between the new bike and my old one, and it clearly shows I was expecting the new bike to have 11/28. The cassette has been replaced once or twice since then and I always thought the mechanics at the shop put on a new cassette that was the same as the old one. So either the bike originally came with the wrong cogs or somewhere along the way someone changed the cogs without telling me. Maybe this was just a simple mistake, or maybe there was no 11/28 in stock at the time it needed to be replaced and someone was just being lazy and using whatever cassette they had available without asking me first. Either way I'm feeling... not mad, but definitely upset. I have always trusted the people at this LBS. I'm not sure what I will do about this; I will definitely point it out to someone at the shop, since it's a quality control issue. I just haven't decided yet if I should email the owner directly or talk to someone else.

Assuming the bike's original cassette was really an 11/28, I probably didn't notice the change to totally different gears because it was most likely done over the winter when I wasn't riding as often.

I'm really disappointed by this.

Anyway, I will rerun Sheldon Brown's calculator with these numbers. But the big thing is that my largest cog right now is NOT a 28 -- it's only a 26. Trying to look on the bright side -- I will be gaining two easier gears than what I have now when I make the change.

[ny biker]

Okay so, new parts have been ordered and the bike is at the shop. It should be finished in a couple of days.

Old: SRAM Rival 10-speed group set
Compact double crankset, 50/34
10-speed cassette, 11/26
short-cage rear derailleur

New: still all SRAM Rival 10-speed
Compact double crankset, 46/34 (swapping out the large chain ring)
10-speed cassette, 12/32
SRAM Rival WiFli mid-cage rear derailleur

The old chain should be long enough so they will probably only replace it if it's worn.

I spoke with several people at the LBS to confirm all this should work well together. Their answers were based on their own bike set-ups as well as some changes that they've made for customers' bikes.

And now after almost 6 years of using only the small ring, I get to re-learn how to shift.

[Crankin]

That sounds like a good plan. Glad you got this sorted out.

[emily_in_nc]

Excellent! That is going to be a nice change. I'm looking forward to doing something similar with my Trek next year unless I decide to spring for a new bike entirely. Will depend on finances. Either one will be a help on the hills!

[north woods gal]

I agree, that is a very nice change. My 2013 Domane Trek road bike is a standard Shimano 105 compact 50/34 up front, but a not too bad 12-30 in back. Gets me by for our hills, up here, but just. If I'm running out of gas, so to speak, or fighting a stiff headwind to get up one of my "special" hills (they all have names, now ), I find myself wishing for one or, even better, two more gears to help.

Speaking of advertised specs being off, my new Salsa Warbird was advertised as having a 46/36 up front, but when I looked, it was actually a 34 on the small ring. Had planned on changing it to an even smaller ring, but instead went from an 11-30 in the back to an XT 11-32. Still very close to the Domane at the low end, 34 and 30 versus 34 and 32, but even that one extra gear makes a difference.