Can a 12-25 cogset be changed to 12-27 easily?

[emily_in_nc]

I discovered yesterday riding out in Shawnee Mission, KS that even in my granny up front, the 25 cog in back was quickly reached, and I was really struggling on the surprisingly large hills (our first ride out that way) in my very lowest gear on my new-to-me Trek Pilot. I'm used to riding my Bike Friday, which was built for touring with mountain gearing (12-34) in back plus the smaller wheels, giving a tiny low gear that can get me up just about anything other than straight vertical.

The Terry Isis I rode back in 2003 had 12-27 in back, so I am wondering if I could have the 25-tooth cog changed to a 27t on the Pilot with no derailleur change, anyone know? I know that only gives me one more gear, but that's exactly what I needed yesterday!

Also, at the same time, I'd like to have the "cheater brakes" (don't know what they're officially called) removed from the handlebars. I never use them, and the bars are narrow enough (36cm) that I really can't ride on the top at all with those brakes installed.

Is this an easy DIY or something I should have the LBS do?

Thanks!

[OakLeaf]

What rear derailleur do you have? The stock long cage Ultegra? If so, it's probably the same one I have (my bike is '07 vintage, not sure the model number), and all it takes is a little tweak of the B-screw and I'm set. The 27T cog makes all the difference in the world on those long hilly steep rides. I don't even have to readjust my cable, though YMMV on that.

(But, plan on replacing the whole cassette. You *might* be able to find the right cogs at a swapmeet, but Shimano doesn't sell individual cogs, or actually, the lower gears come fused together anyway.) They're easily swapped out so if your 12-25 isn't worn out, you can keep it for your flatter rides.

Can't help you on the suicide brakes. Were they added on to the bike? Trek's archive says your bike should've come with R700 brifters (also same as mine).

[Owlie]

I'd have the shop do the brakes. That's something I'm not comfortable messing around with. (Would probably also require re-cabling.)

You should be able to swap the cassette out relatively easily--but I agree with Oak, you're probably going to have to replace the whole cassette.

[emily_in_nc]

Thanks for your input, ladies. I'll have to check on the derailleur.

The cheater/suicide brakes were original equipment on this bike, along with the R700 Brifters. I suspect the bike was marketed towards women who hadn't ridden in a long time and thus wanted a more relaxed geometry, so perhaps Trek thought the extra brakes would help them feel more comfortable...I dunno. But I'm used to the regular brifters and don't even remember the others being on there except when I want to ride on the tops and they are there taking up space!

[emily_in_nc]

Following up on my own post...looks like 12-27 cassettes are only available in 9-speed. I need 10-speed. Ultegra CS-6700 comes in an 11-28 or 12-30. Looking on ebay, appears I'll have to pay at least $80 (probably more, with shop markup) to get that, excluding labor; and then whatever they'd charge to redo the brakes. And I would probably need a longer chain and possible a new derailleur as well, if my bike doesn't use the long cage. One thing leads to another, I guess!

I'll have to wait to decide when/if to spend the money -- was hoping not to have to put a lot more money into bikes for awhile as I've just bought two bikes in the past half year, plus some gear, tires, etc.

[OakLeaf]

The 105 cassette comes in 12-27, 10-speed. You don't mind a few extra grams, do you? I have never noticed a difference in shifting between Ultegra and 105 cassettes. Plus, it's cheaper! (And your bike specs with a 105 cassette originally, anyway.)

If you've got a triple up front, your derailleur is big enough for the 27. Going to the 11-28 Ultegra cassette *might* be an issue with the older derailleur, but it appears you and I have the same drivetrain, and the 12-27, 105 cassette is not a problem. I don't even swap the chain, it's close enough within a link, though if you were going to wait until you replace your chain anyway, you might make it a link or two longer with the 27T cog.

Really, swapping cassettes is no big deal. Fifteen minutes' work. No idea what a shop might charge, but it really shouldn't be much. A cassette tool and chain whip are good things to have around anyway.

Sizing and cutting brake housing, OTOH, is a PITA, and so is re-taping handlebars IMO, and I'd happily let the shop do that.

[emily_in_nc]

Ah, thanks, Oak! That is all very reassuring. Yes, I have a triple up front (that's why it's so embarrassing that I maxxed out my gears with the granny yesterday! But let me tell you, this part of Kansas is NOT flat at all!)

I may just be able to do this after all...actually, my DH has replaced cogsets before, but I am not sure he brought all his bike tools with us to Kansas. If not, we would just have the shop do it. I will talk to them the next time we're in to get an estimate of costs. I'd love to stay with Ultegra since I've already been adding weight to the bike with my new Mirrcycle road mirror and all the crap I carry in my seat bag, but if it makes a sizeable difference in cost, I'll go with 105.