Bicycle Mechanics - Custom Shimano 10 speed gear range.

I'm considering a custom gear combination for my Century-ride bike. The bike has a 50-39-30 Shimano 105 triple.

I plan to use the middle chainring 90% of the time. The large chainring would be used for traveling down longer hills. The small 30t chainring is my bail-out gearing.

I'm considering this combination 11-12-13-14-15-16-18-21-24-27. I have all the parts except the 18t gear. I would expect to use 14-15-16-18 X 39t most of the time.

Shimano sells an Ultegra 11-12-13-14-15-17-19-21-24-27. I like having a 16 and the 18 looks more usefull than the 19.

Will this combination shift well with an Ultegra GS long reach RD?

You shouldn't have any issue using a one tooth smaller cog in the middle of the cassette. Unless you are using a Shadow rear derailler, the derailler will track to the cassette (instead of moving along a set path).

Thanks, The bike has 105 STI brifters.

Michael

Hey Barrett, :)

I know exactly what you mean... a 16-18 jump is smaller than a 15-17. I bought a whole cassette just to get an 18 for my "roadie" MTB. :roflmao2:

Too bad shimano won't just do like SunTour used to do and sell any single you wanted.

Your total of 36 teeth is a fair amount of chain to wrap around a derailleur cage, but your long arm should do it just fine with just the right chain length. And wow... that's a range of 30 to 123 gear inches! That's not just "downhill"... that's "base jumping".

On the rebuilt Raleigh I gave up everything on the top because I don't use them, and run a 24-34-44 with an "off the rack" 8 speed 12-13-14-15-16-17-19-21 for a range of 31 to 99 gear inches.
http://i17.photobucket.com/albums/b90/compost_bin/bicycle/IMG_2956.jpg




Greg

Hi Greg,

That looks like a nice set-up.

The funny thing is: I have been using a 12-27 and a 44t single chainring with good results. However, I started doing events away from home and hills with more than a 5 to 10% grade were a problem.

With an 11-27 cassette, I'll be on the 39t from 12 to 26 mph. The big and small chainrings will be for special situations.

I'm even considering removing the big chainring and putting a 46t on the middle ring. The 30t small chainring would be my bail-out for hills.

Michael

I was using a 30-39-52 crank and 11-28 9spd cassette with a Tiagra long cage without issue.

I can't imagine anything less than 30 gear inches being helpful.

Hi Greg,

That looks like a nice set-up.

The funny thing is: I have been using a 12-27 and a 44t single chainring with good results. However, I started doing events away from home and hills with more than a 5 to 10% grade were a problem.

With an 11-27 cassette, I'll be on the 39t from 12 to 26 mph. The big and small chainrings will be for special situations.

I'm even considering removing the big chainring and putting a 46t on the middle ring. The 30t small chainring would be my bail-out for hills.

Michael

Hi Mike,

If you did that, you could eliminate some rotating weight and still have a 113 inch high gear. That's one reason I went so small up front, to be able to run a very small tight cassette and still have a good low gear. I agree with fordman, 30 is more than enough.:)


Greg

You could do that but if it was me I'd just run the standard 12-27. You can get more speed out of a good aero tuck than you can out of the 11. And that 18 to 21 is a big jump.

Al

I agree with fordman, 30 is more than enough.:)

I'm sorry but I'll never understand why people make blanket statements like this. Perhaps for your terrain, your conditioning, and the kind of cycling you do, 30 gear inches is plenty low but that's just you and where and how you ride. There are a million different reasons why someone might want a lower gear and I certainly wouldn't want to see a new rider disuaded from cycling simply because all the "real" riders won't use a triple or a gear lower than 30 gear inches or whatever the latest arbitrarily set standard happens to be. I'm young, ride a light bike, have been cycling thousands of miles a year for 5 years now and I still use my 30/27 combo on certain hills around here. My new commuter will have a 28/27 (28 gear inch) combo and I know I'll need it.

3T jump with a mixed cassette isn't that bad. just slightly slower in the shift and might be a bit more finicky when the chain starts to wear out.

if my 9sp cassette mixes are any indication, chain wear is the number one cause of bad shifting performance, followed by cable bind and stretch.

3T jump with a mixed cassette isn't that bad. just slightly slower in the shift and might be a bit more finicky when the chain starts to wear out.


I was more concerned with what it does to your cadence. Mechanically the shift would be fine.

You could do that but if it was me I'd just run the standard 12-27. You can get more speed out of a good aero tuck than you can out of the 11. And that 18 to 21 is a big jump.

Al

I'm trying stay on the middle ring for most of my riding.

The 11-27 cassette gives me a 10 to 25.5 mph speed range on the middle 39t chainring. I would only need the 50t chainring while sustaining speeds above that range. This might include a few longer hills and/or faster pacelines.

The 11-16t upper range on the 11-12-13-14-15-16-18-21-24-27 cassette allows very close gearing for speeds in the 17 to 25 mph range. I'm in this range about 90% of the time. A standard 11-27t with 11-12-13-14-15-17-19-21-24-27 cogs starts to jump more than 10% at about 18.6 mph. I had a 11-25 cassette with a 11-12-13-14-15-17-19-21-23-25 on this bike before and did not like the 13.4% drop in cadence between the 15t and 17t cog at that speed.

I can use the 11t on the cassette to keep me from shifting the chainrings at 24 mph, and I can sprint to 30 mph plus if needed in the 39t & 11 combo. The jump between 18 and 21 is at a low speed of 15 mph. I'm never holding that speed in normal riding, I'm usually 20% faster or more. If I'm climbing a long hill at that speed, I'll just change down to the smallest chainwheel.

This is all about having a close gear range at my normal riding pace, and have reasonable options above and below that range.

Michael

16 > 18: 12.5%
18 > 21: 16.7%
21 > 24: 14.3%
24 > 27: 12.5%

so yes, it does give quite a big jump, but at this range it'll be a hill or severely strong head wind.

16 > 18: 12.5%
18 > 21: 16.7%
21 > 24: 14.3%
24 > 27: 12.5%

so yes, it does give quite a big jump, but at this range it'll be a hill or severely strong head wind.

...and that's what the 30t small chainring is for.

Michael

it will work fine, and I don't know why we are complaining about your custom gear ratio that you know will work for you.
that's what custom is all about, for you, by you :)

I'm sorry but I'll never understand why people make blanket statements like this. Perhaps for your terrain, your conditioning, and the kind of cycling you do, 30 gear inches is plenty low but that's just you and where and how you ride. There are a million different reasons why someone might want a lower gear and I certainly wouldn't want to see a new rider disuaded from cycling simply because all the "real" riders won't use a triple or a gear lower than 30 gear inches or whatever the latest arbitrarily set standard happens to be. I'm young, ride a light bike, have been cycling thousands of miles a year for 5 years now and I still use my 30/27 combo on certain hills around here. My new commuter will have a 28/27 (28 gear inch) combo and I know I'll need it.

Hi Joe, :)

It's just an opinion of no more weight than anything anyone else says here. My comment was directed to Michael who rides a very light and fast road bike. My 33 pound road converted mountainbike has a similar 28 inch low gear as what you use (24/23)... but on my lighter road bike, 30 is fine. Any cyclotourist carrying gear or riding off road will certainly use much lower gears.

As far as terrain and conditioning. I live in a very steep canyon, and can't ride anywhere without grinding uphill or screaming downhill.

Perhaps you were addressing someone else because I said nothing about "real" riders don't use a triple. In fact I've never owned a bike that didn't have a triple and consider myself a "real" rider who is over 60 years old and has been riding bicycles for over 50 years...

...so, believe me... I need all the help I can get!:roflmao2:


Greg

I was using a 30-39-52 crank and 11-28 9spd cassette with a Tiagra long cage without issue.

I can't imagine anything less than 30 gear inches being helpful.

Thank you everyone,

I'm primarily concerned about mechanical issues with the cassette & RD. I'm now sure this won't be an issue.

The bike is a 60cm sized fast century bike, at about 23 lbs, and about 25 lbs fully loaded for an event. I agree the 30 gear inches should get me up 99.99999% of the roads I travel.

Michael

Hi Joe, :)

It's just an opinion of no more weight than anything anyone else says here. My comment was directed to Michael who rides a very light and fast road bike. My 33 pound road converted mountainbike has a similar 28 inch low gear as what you use (24/23)... but on my lighter road bike, 30 is fine. Any cyclotourist carrying gear or riding off road will certainly use much lower gears.

As far as terrain and conditioning. I live in a very steep canyon, and can't ride anywhere without grinding uphill or screaming downhill.

Perhaps you were addressing someone else because I said nothing about "real" riders don't use a triple. In fact I've never owned a bike that didn't have a triple and consider myself a "real" rider who is over 60 years old and has been riding bicycles for over 50 years...

...so, believe me... I need all the help I can get!:roflmao2:


Greg

Yeah, I went a little overboard in my gearing rant :) Go to the road forum and read all the triple crankset scorn and you'll see what I mean though.

Hi Joe, :)

It's just an opinion of no more weight than anything anyone else says here. My comment was directed to Michael who rides a very light and fast road bike. My 33 pound road converted mountainbike has a similar 28 inch low gear as what you use (24/23)... but on my lighter road bike, 30 is fine. Any cyclotourist carrying gear or riding off road will certainly use much lower gears.

As far as terrain and conditioning. I live in a very steep canyon, and can't ride anywhere without grinding uphill or screaming downhill.

Perhaps you were addressing someone else because I said nothing about "real" riders don't use a triple. In fact I've never owned a bike that didn't have a triple and consider myself a "real" rider who is over 60 years old and has been riding bicycles for over 50 years...

...so, believe me... I need all the help I can get!:roflmao2:

Greg

Hi Greg,

I need to come visit you in Moab :).

Michael

Yeah, I went a little overboard in my gearing rant :) Go to the road forum and read all the triple crankset scorn and you'll see what I mean though.

It's obvious that you feel attacked for having a triple crankset on your bike, and for that I'm sorry. The truth is, for many people in that forum, there is little need for a bailout chainring. It may come across as sounding prideful and belittling toward those who choose lower gearing, but I think most people who "wouldn't be caught dead riding a triple" simply feel that way because they'd be carrying around an unused ring if they had one. Gearing is very personal, and if a sentiment of "Triples are for Cripple's" is running rampant, it's probably a sentiment flowing between a small handful of people on that forum who feel it necessary to push the point at every opportunity, not even necessarily the majority. I think it's comforting to assume that those who suggest that Triples are somehow for lesser folks are simply stubborn people who aren't willing to admit that they really would benefit from the expanded gearing offered by a triple. But I think that's a damaging assumption to make. Some guys are actually strong enough to spin a 39/23 up a 7 percent grade. I'm personally not (yet) in that catagory, but it's surely not necessary to feel intimidated or defensive toward those who can. Just my $.02

-Jeremy

...And go to the long distance forum (you know, those Cripple's that do 400K in 48 hours :rolleyes: ) and you will see that more than half use triples: http://www.bikeforums.net/showthread.php?t=578809

Michael

It's obvious that you feel attacked for having a triple crankset on your bike, and for that I'm sorry. The truth is, for many people in that forum, there is little need for a bailout chainring. It may come across as sounding prideful and belittling toward those who choose lower gearing, but I think most people who "wouldn't be caught dead riding a triple" simply feel that way because they'd be carrying around an unused ring if they had one. Gearing is very personal, and if a sentiment of "Triples are for Cripple's" is running rampant, it's probably a sentiment flowing between a small handful of people on that forum who feel it necessary to push the point at every opportunity, not even necessarily the majority. I think it's comforting to assume that those who suggest that Triples are somehow for lesser folks are simply stubborn people who aren't willing to admit that they really would benefit from the expanded gearing offered by a triple. But I think that's a damaging assumption to make. Some guys are actually strong enough to spin a 39/23 up a 7 percent grade. I'm personally not (yet) in that catagory, but it's surely not necessary to feel intimidated or defensive toward those who can. Just my $.02

-Jeremy

I certainly don't feel intimidated by someone who can spin a larger gear than me uphill. I'm far from the greatest cyclist to ever live. Nor do I feel attacked for using a triple. My whole point was that I really don't care and don't think other cyclists should care what someone else needs for gearing. They should choose their gearing based on their needs and not what's fashionable or cool to ride.

BTW, my daily commute would seem easy if the worst grade I encountered was 7%. For others, the overpass might be the biggest hill they'll ever ride. For the same caliber of rider, it should be obvious that our bikes would be geared differently. For some members of this forum it's apparently no so obvious though.

The actual science of bike gearing is not that complex. It comes down to power, weight, friction, aerodynamic drag, slope and speed.

A triple can be applied a wider range conditions and do it with less cross chaining than a double. Racers can use a double, but will change gearing for every stage. A recreational cyclist can also use a double, but may face compromises.

Michael

Yeah, I went a little overboard in my gearing rant :)

Hey, no problem, Joe... you actually raised a very interesting issue.


Go to the road forum and read all the triple crankset scorn and you'll see what I mean though.

ooh... that sounds like fun. I'll go check it out. :)

Greg

I'm even considering removing the big chainring and putting a 46t on the middle ring. The 30t small chainring would be my bail-out for hills.

This setup with 46-30 chainrings would be similar to what I run. I actually use 46-28 by doing the same thing - using only the inner and middle positions on a triple crankset. I then have an 11-26 stock SRAM cassette. The lack of a 16 tooth cog does bother me, and I decided that my ideal cassette would be 11,12,13,14,15,16,18,20,23,26. However, the largest three cogs are bound together on stock cassettes, making the 20-23-26 combo difficult to achieve without going fully custom. I've therefore decided to stick with the stock 11-26.

For me, the 18-21 would be too big of a jump - I've tried the stock SRAM 11-28 cassette, but the 19-22 jump on that really bugs me every time I do it. I still wanted the 28 tooth cog, so I took a 12-25 cassette, removed the 16 tooth cog, and put a single 28 tooth cog at the top end that I got from an old MTB cassette (an 11-32 Deore LX I believe). That gave me 12,13,14,15,17,19,21,23,25,28, which I now keep on my cyclocross wheels (whereas the road wheels get the 11-26).

For me, the 18-21 would be too big of a jump - I've tried the stock 11-28 cassette, but the 19-22 jump on that really bugs me every time I do it. I still wanted the 28 tooth cog, so I took a 12-25 cassette, removed the 16 tooth cog, and put a single 28 tooth cog at the top end that I got from an old MTB cassette (an 11-32 Deore LX I believe). That gave me 12,13,14,15,17,19,21,23,25,28, which I now keep on my cyclocross wheels (whereas the road wheels get the 11-26).

Hi Chris,

Always good to hear from you.

If I was using a 42t or higher chainring, the jump from 18 to 21 would bother me also. By using a 39t as my primary chainring, the jump from 18 to 21 happens at a speed that I am able to avoid while riding on the flatter routes near home. I live in Chicago where most most of my riding is above 16 mph.

However, I also travel with the bike. The 30t chainring is for hills away from home. If I'm facing a slope that slows me to 15 mph or less for more than a 250 meters, I'll go to the 30t chainring. At higher speeds, I'm planning on using the 50t chainring while on the top 6 cogs only, and will downshift to the 38t chainring at about 22 mph.

If I used a 42t or higher chainring, I would use a 12-27 cassette with 12-13-14-15-16-17-19-21-24-27 gears. this provides the same speed-range as the 11-27 on a 38t, with speeds of 12 to 26 mph, that I am seeking.

Michael

16 > 18: 12.5%
18 > 21: 16.7%
21 > 24: 14.3%
24 > 27: 12.5%

so yes, it does give quite a big jump, but at this range it'll be a hill or severely strong head wind.

My concern would be the shift from 21 to 18 and what it does to the cadence. In a strong headwind, what we often have, I might get caught between gears. I'd be ready to trade the 11 for a 19.

With an 11-27 cassette, I'll be on the 39t from 12 to 26 mph. The big and small chainrings will be for special situations.

Have you checked chain line to be sure you can use all 10 gears while in the middle ring? Something to consider.

I can use the 11t on the cassette to keep me from shifting the chainrings at 24 mph, and I can sprint to 30 mph plus if needed in the 39t & 11 combo.

You really don't like the big ring, do you?
On flats if I see I'm going to be above 20 for long I'll switch to the 53.

My concern would be the shift from 21 to 18 and what it does to the cadence. In a strong headwind, what we often have, I might get caught between gears. I'd be ready to trade the 11 for a 19.

honestly it seems like there's plenty of overlap in the 30 and 39T at the 15~27T range that the jump doesn't seem like a big issue.
combo - GI - % change
1> 30x27 29.67 12.50%
2> 30x24 33.38 14.29%
3> 30x21 38.14 1.11%
4> 39x27 38.57 12.50%
5> 39x24 43.39 2.56%
6> 30x18 44.50 11.43%
7> 39x21 49.59 0.96%
8> 30x16 50.06 6.67%
9> 30x15 53.40 7.14%
10> 30x14 57.21 1.11%
11> 39x18 57.85 6.51%

http://www.panix.com/~jbarrm/cycal/cycal.30f.html