rykoala

I am building a commuter based on an old Nishiki MTB, but want to do long distance cycling in the future when I get back in shape. I used to commute every day but since I got hurt (herniated disk) I have stopped riding. So I've given up fixed gear riding for now in favor of a 3x7 set up. I'm matching two cassettes together for the 7spd cassette I want. For chainrings I am using triple cranks and have the options of 52/48/40/38/28. I have cogs from 12-32, but plan on doing 32/13, or maybe 13/28.

I have done some reading and I think that 52/48/28 would work well, as the granny is just a bail out gear anyway. The half step gearing might give me a better way to fine tune cadence. Sheldon said that people think it looks good on paper but in practice is a pain in the butt. Is there any reason that half step gearing wouldn't work well?

I could also do 52/40/28, 52/38/28, etc etc.

I've probably worn out the gear calc on Sheldon's site and so It has generated one serious question:

Has it been anyones practical experience that getting up a monster hill or pass that having a 20" gear over the 30" gear you have would make that much of a difference?

I can't quite decide how I want to put the gearing together. I can go as low as 22.5" with 28/32. Do I really need to? I've contemplated replacing the 28 with a 24, I could get down to about 18". Is that too low?

Thanks for the insight.

Bacciagalupe

If the biggest gear is a 52T, the lowest you can go with a typical triple is 30T. IIRC most double front derailleurs can go a max of 16T, and triples can go 22T.

Rear derailleurs also have maximum cassette sizes. So your derailleur might only cover 11-27, 11-28. IIRC you need a long cage derallieur to cover up to 32-34T cassettes.

As to gearing, 25" is pretty low, and would be great if you're ever carrying loads or hit hills somewhere around Hour 7 of your ride. I'm a big fan of spinning as I like functional knees. Anything lower than that is useful if you're touring, otherwise if your knees are in good shape it's kind of overkill.

supcom

I think you should reconsider using 7-speed rear. Getting a wide spread of teeth on a 7-speed is what's leading you to need half-step gearing. While this made sense in the 5 and 6-speed days, the advent of 9 and 10-speed cassettes can allow you to get a good spread in teeth and still have fairly close shifting in the mid range.

In any event, consider carefully your top end. Most people have high gears that are only useful for pedaling down descents when they would be better off just coasting. If you reduce the high end, then you can get closer spacing in your cruising gears with a couple bailouts for steep hills.

In the end, you may need to experiment with different gear combos. Only you can determine how high or low you need to go. But, for long distance riding, remember that you may need to climb some steep hills after having already ridden a couple hundred miles. You just can't have gears too low sometimes.

rykoala

Thanks for the informative posts! The reason I'm going 7spd is because the wheel I already have is a 7spd shimano silent clutch hub and I love it. Its so QUIET. I have a 8spd wheel that needs rebuilding but its not silent. Maybe time for a 8/9spd silent clutch hub hmm?

Last night I was crunching numbers again and decided that yes, the gearing was a bit high. I am thinking that maybe 48/44/28 would be better, and when I upgrade the wheel and go 9spd I could change the gearing again maybe.

Thanks a lot for the informative replies.

Speedo

Holy crap. YES!!!

There is a huge difference between a 20 inch gear and a 30 inch gear. If you are very strong then it might not make much difference to you. If you are nursing aging knees it might make all the difference in the world. This year I started using really low gears. Old low was 29 inches, new low is 19 inches. It has made a tremendous difference. I used to fear steep hills and try to avoid them. Now I just ride up them without any particular concern.

I typically don't use that 19 inch low, but I use the next up, 21.5, for all very steep hills.

This is one of these "your mileage may vary" cases. In another thread I asked the question is it possible to have a gear that is too low. Pretty much, the answer was no, and it depended on the circumstances.

I would recommend that you try and borrow a touring bike with really low gears and take it out on the longest, steepest hills you can find. Get a sense of how you would ride if the low end gear selection was not dictated by the fact that you just don't have a lower gear to go to.

I weigh 200 lbs, I ride a 25 pound bike, and I'm 50 years old. As noted above, I can be comfortable on the steepest of hills with a 21.5 inch low. On the other hand, I can't tell you how happy I am, when I am riding up those steep hills, to know that I've got the 19 inch gear in reserve!

Speedo

rykoala

Thank you once again for such finely detailed answers. This is *really* helping me decide what I want to do. Here's what I have come up with. I lack funds to go even 8 speed right now (that wheel needs a rebuild!) but I think I'll do ok.

(ALL MEASUREMENTS IN GEAR INCHES)

52/48/28 (later, 24)
13/15/18/21/24/28/32

That gives me gearing half step gearing like this:
103-95-89-82-75-69-64-59-56-52-48-44-(41-38) The last two are on the 32 and wouldn't be used. the 75-69 would be on the 48/52-18, so switching between them (my two favorite gears) would be a cinch.

On the 28, starting with the 18 I get 40-34-30-26-22

I don't need the high end of the 13, but I may as well use it. If I use any more gears I end up with redundant gears. As mentioned it works best with a 5 or 6 speed rear end. Which is fine, I considered doing that anyway LOL. I'm not into having tons of gears just yet. I just want something reliable and simple. As it is, I may omit the 13 and just put in extra spacers so that the cassette and spokes have some room between them in case I drop the chain. I ruined a wheel that way. That's the one that needs rebuilding....

grolby

Actually, the size of the small ring seems to have little functional significance, as long as your middle and big rings aren't too different in size. You can set up a triple with 24/39/52 if you want, it'll work just fine.

lmzimmer

I for one am unimpressed with half step/granny gearing. I have it on an 83 trek 520 and while it might have made more sense then it is a nuisance now. If you have brifter instead of down tube shifters it would be easier to deal with but the double shifting (like double clutching on an old car) is only fun at first.

gosmsgo

Are you ever going to pull a trailer?

I have a 22 tooth chainring up front on mine for pulling 300-400 pounds in a trailer.

Between you and me sometimes I use it when I'm lazy and just want to spin lazily up a hill at 5 mph.

I am carfree, ride at least 100 miles per week and sometimes I just want to get somewhere and not get a workout. : )

stapfam

You can if you wish but rub on the front derailler can get noisy. And that amount of teeth difference coupled with say an 11/32 rear cassette could cause problems even with a long reach rear derailler.

I have the Ultimate geared machine. It will get us up to 35mph before we start coasting and we can crawl up hills at 3 mph. The max Shimano state a front derailler will shift is 22t. You can take 24 if it is set up precisely to take in the large and the small ring. So I have it set up with 48/36/24 chainrings. The even spacing does not give a big jump from ring to ring so you can get a wider spread of gears for each ring. The rear is 9 speed 11/32 so our highest gear is 48/11 and lowest 24/32.

You may have guessed that this machine is a Tandem as I said "we" but this is a Full offroad tandem weighing in at 55lbs in ride trim.

Without the severity of the offroad hills- The chain rings could go higher but I doubt we could pull much more than 50/11 in any case. And it is surprising how many times we use the 24/32 on the road aswell.

john bono

Whether the gear is too low or not depends on where you ride. If I lived out in the flatlands, I wouldn't even get a triple. Since I live in NW CT, 30F/27R gear is still a little too tall for some of the hills I climb during my commute.