Hybrid Bicycles - Gearing for my sirrus

So I have this sirrus frame I'm going to ride. I've acquired a 53-39 double. I have the 8 speed cassette for the back wheel too (12 - 26 I think). I would like to put a wider-range cassette on the back... so I gather a mountain bike derailleur is needed. Do they work with barcons? I'm thinking of converting to road bars too. Anyone got any thoughts?

So I have this sirrus frame I'm going to ride. I've acquired a 53-39 double. I have the 8 speed cassette for the back wheel too (12 - 26 I think). I would like to put a wider-range cassette on the back... so I gather a mountain bike derailleur is needed. Do they work with barcons? I'm thinking of converting to road bars too. Anyone got any thoughts?

Hummn! Well one Idea I had (and you're free to use my idea) is to make an 8 Speed IGH Sirrus; however, this isn't exactly what you asked. For '07 the Sirrus came with a 12 to 25 and a 48x38x28t triple on the front. Rear Derailleur is a Sora long cage so a MTB rear derailleur would work. Also, if you check the Sirrus threads the Drop bar conversion is discussed and demonstrated at length and yes, barcons will work..:thumb:

First you need to figure out what you need for your low end. I run 52/40 and 14-28 (6 spd freewheel) with a short cage derailleur. Up to a 30 reportedly works fine (according to Harris Cyclery). Someone correct me if I am wrong, but I think running a double up front helps your cause, because you have a smaller tooth delta between to largest and smallest chainrings for the derailleur to take up. There's a good article on Sheldon Brown's site I am sure...I'll let someone else search for it...it's late!

I own a 2006 Sirrus LTD. It has Shimano Ultegra drivetrain components (FD-R770 front derailleur for flat bars, Ultegra short-cage RD, 10-speed Ultegra cassette, R600 wheels, R770 Rapidfire shifters), and Shimano 105 brakes (with Tektro carbon levers). The LTD is a double (two chainrings, 50T and 36T). That is the stock from-the-factory configuration on my bike.

Specialized offers a range of component levels for the Sirrus.. I have seen everything Shimano on them from Ultegra to 105 to Tiagra road components as well as MTB components like Deore XT to Alivio to the lowest-end Altus/Acera.

I'm not sure if there are any differences in the spacings and dropouts between the Sirruses with road components vs. the Sirruses with MTB components, so you might want to research that a bit.

My Sirrus is older (2002 Sirrus A1). It has (I think) 135 mm rear spacing, (stock) 11-30 cassette, 28-38-48 triple in front, which gives a low of 26 inches, a high of 122 inches. Once in a while I wish for a lower low, but not enough to do anything about it. 26 inches is pretty low.

It came with an Acera long-cage RD, and a Nexave FD. The Nexave was cheap-looking, but worked just fine.

I've changed to a Sora FD, because the Nexave didn't allow enough clearance to mount fenders (had to change to friction shifter for the FD, since Nexave is a "mountain" FD, and Shimano road and MTB FDs pull different amounts of cable).

I tried to change to a Sora long cage RD (RD-3300). I wanted to change it just because I wanted an allen-bolt cable anchor (didn't want to carry a wrench on long rides, and this Acera has a nut anchor). The Acera functions just fine, though. The Sora RD was advertised to handle up to 27 or 28T, but I figured I'd try it--- no go, though.

I might watch out for a Deore RD (or some other MTB RD). Not a high priority for me, though.

Your 39x26 low while give you something like a 42-43-inch low, which is fine for some people, though not for me. It would kill my knees on the hills around here.

A 30-tooth big cog, 39x30, would give you a low of something like 34 inches. That might be OK.

Or if you went for a triple in the front (which you probably would prefer not to do, since you've already acquired a perfectly good double, and you probably don't want to spend more $$?), you could get a triple something like mine and end up with something like a 28x26 low, which 30 inches--not bad, probably.

As far as shifters, Shimano 8-speeds all pull the same amount of cable (except for some old Ultegras), so I think any 8-speed Shimano indexed shifter should be fine, whether you get a road or MTB rear derailleur. For the FD, it does make a difference, as I said above. If you want barcons, you will need to run the FD shifter in friction mode with an MTB FD.

Another variables someone else may know more about than me: does a Shimano barcon pull enough cable (total range, stop-to-stop, I mean) to run a Shimano MTB FD in friction mode? To avoid dealing with that question, you'd probably just want to run a road FD. But you'd probably want to run in index mode for the FD anyway, which would require a road FD, I think, for the proper amount of cable pull.

I've changed mine to drop bars. PM me with questions, if you like.

I have a road triple on a hybrid conversion I'm riding now, and I've never used the smallest chainring at the front. It's pretty flat around here too, and I don't see myself using this bike out west or in the hillier parts of Ontario even.

I do like the idea of running a 12-32 cassette or something more like that in an attempt to give myself a bit of wiggle room with some lower gearing if I ever find myself facing crazy winds or something... I did do some reading on long cage vs. short cage and I still need to read more 'cos I'm still foggy on the overlap.

I think I will get a tiagra or 105 front though, it seems road derailleurs give good fender clearance, which is a big plus for me.

I'll post more when I get some more reading done.

Right. If it's pretty flat there, you should indeed focus on having the right gear choices within the range you normally ride. In fact, a 53x 12 high gear might well be higher than you'd need. '70s 10-speeds commonly had something like 40 or 42/52 in the front, and 14-30 (or -28 or -32 or -34) freewheel, which gave a decent range for "average" riders in most terrains. If you have a 53x14 high gear, that might be plenty (over 100 gear inches? Don't feel like looking it up now), and then you'd have another cog available in the mid range, where you probably want more choices in flatter terrain, anyway.

Long cage vs short: check the specs of the derailleurs you're considering. If you have a double, without a granny in the front, you have less to worry about, generally.