Cassette Question
 

I just finished a Soma Double Cross build. I will bemusing the bike for credit card touring and commuting to work.

I have a Shimano 105 5700 double drive train and was looking for suggestion on a cassette that would be suffice. I know a lot of touring bikes use triple crank but I am going to use the double and see how it works out my first year touring.

Are the any other options other then Shimano?

I am planning 2 tours next summer one around Lake Ontario and one around Lake Erie.

I plan on doing a cross Canada tour in a few years.

You can tour on a double; I've done it. But my enjoyment of bicycle touring soared when I increased the range of available gears. Specifically, I added a third ring to make it easier to climb long steep hills and ride into headwinds.

If you want those low gears, but the idea of the double attracts you, consider a cassette that biases the low range: say 24-38T or 22-36T, rather than something more racy like 38-50T or 32-44T. You might miss having the higher gears, though.

Shimano SLX cassettes have some wide ranges (to 34 or 36 teeth I think). You'll need a long cage derailleur but these should work with your 105 crankset.

I have a double cross with a compact crank and a 11-34 cassette. I did the Pacific Coast and the Serria Casades this fall pulling a BoB trailer. The route was all up and down with very little being flat. I was able to work with what I had but was in the 34-34 for alot of the climbing. I would have a triple if I was to do it again self supported but would keep the double with a credit card. But for using the bike for most tours or the first ones that are on your wish list the double would be fine. You will not be pulling a trailer and I can't imagine what you would do with all the low gears that you would have with the triple.

Hi lucky 1976.

I have a 26, 42, 52 going against a 12-36 9 speed in the back and I could easily live without the 52 when loaded down as for commuting I use the taller gear but when you look at the overlap in a gearing printout I could get most of the range with the 42 using different rear gears.
A good calculator that’s helped me a lot is this one.

http://home.earthlink.net/~mike.sherman/shift.html

Sheldon’s page on gearing was also a big help.

http://www.sheldonbrown.com/gear-theory.html

I messed around quite a bit with trying smaller granny gears that in turn caused me to lower my middle chain ring because of the shifting issues when dropping more than about 16 tooth difference. The real revelation happened for me when I went to the larger cassette. Having the 36t in the back made the 26t up front act like a 22t in terms of gear inches and allowed me to keep my center ring reasonably big. I would say with a double that would be even more important for mixed riding (commuting and touring). I never really missed the loss of the smallest gear on the cassette. For me I wanted to find the perfect center ring that I could ride the widest range across the 9 rear gears. What worked for me may not work for you, as we all have different abilities and preferred cadences. But the method of figuring it out is the same for all people. It’s widely accepted that for loaded touring a low gear around 20 gear inch is good and a tall gear at 100 gear inch is more than enough. If I disregard my 52t my range would be 19.4 to 94.3. I would think that would be a pretty respectable range for both touring and commuting.

I’m envious of you planning to do the two great lakes circle tours. My goal is to do the Lake Erie tour at some point. Like many here finding the consecutive time to do it is my biggest problem. If you plan on camping your way around Lake Erie I can offer you a place to overnight and even a tune up if needed just a short distance off Rt 5 on Lake Erie west of the city of Erie. You won’t encounter any great climbs on this side of the lake but about every 10 miles there are large creeks that empty into the lake and most of them have a good grade down and back up that cover about a mile where you will want a nice low gear. Presque Isle state park is worth the 14 mile loop and right off the circle tour loop if you want a great nature/ beach ride to break up the tour. If you do the credit card tour at least wave as you go by. J

I would consider the 12-36 10-speed cassette with a MTB rear derailleur: http://www.bikeman.com/FW6237.html

However a triple will be a worthwhile investment. I started with a double on my Double Cross and switched to a triple with very good results: http://www.bikeforums.net/showthread...ke-componients

Here is a side by side contrast of 50, 39 & 26t triple with the 12-30 cassette a 50 & 34 compact double with a 11-28 cassette.

http://i289.photobucket.com/albums/l...et/image-1.png

Suggest you do what I did: load your bike up with your touring gear and do some one-day test rides over terrain that will be similar to your tours. Like acantor, I found that lower gearing made climbing and headwinds much more manageable. In my case, I started with a 53/39/30 road triple and 12-28 cassette and ended up going to a 48/36/26 trekking crank with the same 12-28 cassette. That was for credit card touring down the Pacific coast; on the 4th or 5th 1000-foot climb of the day even the 26-28 combo starts to feel like an effort...

Interesting comment. The trouble is, with a road triple, you retain all the benefits of a 52-39 double, but simply add the 30T granny.

Nothing says you have to use it regularly, and in fact you can treat your bike as being equipped with a double for most of your riding simply by ignoring the granny. But it sure is nice to have the granny there when the conditions or terrain get tough, or you are just so tuckered out that pushing a 39-28 combination is way too big a deal.

Of course, I do understand that with double shifters it's not possible to re-fit with a triple without going with new shifters. In that case, it becomes an option between the full road double, and the compact crankset.

As mentioned in passing earlier, but needing reinforcing, playing with the cassette with bigger tooth-counts may well require an SGS/long-cage derailleur to be factored into the cost.

Looking at the Shimano tech Docs, there are 5700 and 5700-A derailleurs, which both come in SS (short cage) and GS (medium cage) versions. The 5700 family supports up to 28T officially, and the 5700-A up to 30T. You can probably exceed this slightly, probably 30T on the 5700 and maybe 32T on the 5700-A, by adjusting the B tension screw, depending on the dropout on your bicycle. It'd probably be better to use a GS (medium cage) derailleur for this sort of setup, unless you're comfortable setting the bike up so that you either have too much chain and start to skip when approaching the small/small, or insufficient chain to shift into the big/big, which aren't really ideal to ride in anyways, although it's certainly possible to forget about this while riding and do bad things to your bike (especially trying to big/big on an insufficient chain). Shimano makes a 12-30 10sp Tiagra cassette now that could be good for this sort of setup.

You can also of course just use a shimano mountain derailleur. You can use a 9sp Shimano mountain derailleur with a 10sp shimano or sram cassette and a 10 sp road chain with the rest of your drivetrain. Don't use a 10sp mountain derailleur, as they have different cable actuation ratios.

Only you can decide if your gearing can get sufficiently low for your needs. If you're a strong rider, carrying very little/lightweight gear, and/or are touring in a relatively flat area, this may be fine.

For comparison, a setup with a 12-30 road cassette on a road derailleur would give you a low gear of 30GI, whereas a mountain derailleur would bring it down to about 25GI, which is close to the stock low gear on a lot of touring bikes with road triples. My 2008 Trek 520 had this sort of gearing before I crashed it.