Help on customizing gearing
 

I'm currently bikeless and need a new bike that will have to serve multiple purposes including light/moderate touring, gravel/light off-road, and club rides/racing. I've been fooling around with some of the gear calculator sites to see if I can come up with something that works for all these applications. I should probably be okay with 25-30" low, so I've found what look like two options: 52/39/24 with 13/14/15/16/17/18/19/20/21/23 or 48/32/22 with 12/13/14/15/16/17/18/19/20/21.

I had been thinking more about road groups (105 level), but the 2nd option would require mountain equipment, so my questions are:

1. Is there anything inherently wrong/bad with the gearing ranges I've come up with?
2. To what extent can you mix road/mountain groups on the drivetrain - ie could I use a Shimano mountain crank with 105 shifters and derailleurs?
3. Can 105 derailleurs handle this gearing?
4. Neither the chainrings nor the cassettes are stock in either of my possible solutions and it looks really expensive to change these things - ie 105 crank is 50/39/30 and it looks like the cost to switch to 52 would almost buy me an Ultegra triple! Is there a cost effective way to do this?
5. Anything else I need to consider?

You really can't do all those things well with one bike. Sorry. So pick some place to start - say the road bike. Buy something stock, either new or used, and then figure out how the ratios work for you. Modify as required.

Look for used parts if you do decide to upgrade the drivetrain on your bike. It's just a little cheaper. Good luck. Al

I like to mix and match road and mtb equipment on my bikes. I like Shimano Deore XT derailleurs with DuraAce 9 spd barcons. My cranks are old Deore XT and Coda that I get on eBay. I am old and heavy and really appreciate a few really low gears on my bikes. Last week at the end of a hot day I had to climb the hill in Harper’s Ferry. Fortunately my gearing was low enough. I use a 94/58 crank with 20-32-42 rings with a 12-14-16-18-21-24-28-23-36 cluster. I rarely have to go to the granny, but when I have to it is there. The high is only about 95” but at my age that is fine.

48/32/22 & 52/39/24 are both requiring you to buy new chainrings , plus the crankset .. & BB..

Now IDK if you can mix cassette cogs you have to accept the sets from the factories, just as well

as wearing out non standard sets and making them up from individual cogs is pricey, once let alone repeatedly.. .


I doubt anything but a long cage MTB derailleur can wrap up (52-24) 28t, or (48-22) 26t

I understand you can't do all these things well, so I know there will be compromises. I just thought a single better quality bike would come closer to meeting my needs instead of two or three cheaper ones. Does that approach make sense?

Sorry if I wasn't clear. I have nothing now, so will need to either modify any new bike I purchase or build up a frame. In either case, I'm starting from scratch.

IDK???

My knowledge of derailleur capacity is pretty limited, so I'm not sure if you are talking about the rear derailleur, which I associate with wrap, or the front. I do know that a road rear could not handle every combination in the set ups I was contemplating, but thought it probably could handle the combinations one might reasonably use.

vyborne, please have a look at your first post. You want to do some light touring. You want to do some off road work. You want to do group rides and you want to race. They're all different things that will be almost impossible to do well with one bike. A cyclocross bike will do a reasonable job for some of the stuff you want to do but won't do all of them well. You can race almost anything if you are a beginner but will very quickly find that the winners do ride equipment geared for the competition they enter.

I happen to own 5 bikes: a Cannondale T1 tourer with trailer, a full blown road bike that I assembled from parts for group rides, a singlespeed road bike (because I wanted one) and 2 mountain bikes. They all serve different purposes.

My tourer tops out at 95 GIs and bottoms out at 17. My road bike tops out at around 101 GIs and bottoms out at around 35. My tourer is setup that way because I looked at the ratios I was using with the stock setup and changed the drivetrain to match. Likewise, the drivetrain on my road bike was chosen to reflect how I rode in a group and what I am able to realistically use.

You've got to do the same thing. Get yourself a bike you can afford for the kind of riding you want to do. Ride it for awhile and either change it for something more suited for what you want to do or modify as required. Unfortunately, there are few shortcuts in this life. Al

Well said. Road bike for the club rides/racing, cyclocross for everything else. Most serious cyclists have several bikes in their stable, gathered over time.

I'd go with the lightest road bike I could afford. It can do it all except off road. Get a mtb from a box store for that until you can afford better.

+1 on the cyclocross bike.
It will do just about everything you want. I think you will want two different sets of tires, one for touring and dirt roads, another for training/racing. I think you could easily start racing on that bike, but you will find quickly that you will want/need a dedicated road bike if you get serious about the racing. Gearing will really depend on how you define "light" touring compared to what you need to race at 25-35mph for an hour. That said, I used to see a guy on the Rose Bowl ride on a mountain bike. Speeds would hit over 35mph on the back side and it would last 60-90 minutes depending on the time of year. He was in there the whole time, so it can be done. The only thing you won't want is disk brakes. They aren't legal to race on the road yet.

It looks like you are trying to get road gearing but also some low granny gears for when you really need them.

I have 52/42/24 chainrings on both of my derailleur touring bikes. The 24t is aftermarket, the 52 and 42 were stock. The upshift from the 24 to 42 is a bit slow and requires patience, but it gives me the ability to run road gearing for the 97 percent of the time that I want road gearing, and the granny gears for the 3 percent of the time I want really low gears. I however use a bar end friction shifter on the front, I think an indexed shifter would not work with this wide a range. Some front derailleurs might not like that big a range, I have an 80s vintage Suntour derailleur.

I however am using an 11/32 rear cassette, not the narrow range racing cassettes you are considering, but I do not race. I also use an 8 speed rear, you are looking at a 10 speed system.

Go for it. But, get a really long cage for the derailleur so that later if you need to install a larger cassette, you have the ability to take up that much chain. And, when you install the chain, use as much chain as you can with the derailleur taking the slack, if you cut your chain too short that would limit your ability to put on a bigger cassette later.

Also, be ready for finicky front shifting. Consider getting a front friction downtube shifter, that may help with finicky shifts. Years ago, all front shifters were on the downtube and were friction, any bike shop that has a box of cheap vintage old parts will have an old shifter that they can give you.

Do remember speeds is how many cogs are stacked on the right side of the rear hub,
more = packing them in tighter , 8,9,10,11 all take a particular chain,

the tooth count math is what you use to determine the size of the gear,

ratio of front : rear tells you how big the gear is..