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How to build gravel bike with very low gearing

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How to build gravel bike with very low gearing

Old 01-06-20, 04:31 PM
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How to build gravel bike with very low gearing

Want to build or order a gravel bike with really low gears. Current road bike is a 2014 Madone with 36x11 10 speed rear and 36x22 front chain ring setup from small and middle chain ring of Deore XT triple. The low from a 42x11 rear cassette and 11 speed Shimano GRX 46x30 front chain rings are too big for what I can handle in hills. Don't know if there are chain rings for GRX crank smaller than 46x30. Can't find the specs. Not sure of best alternative front crank. 36x22 with another Deore XT triple? 38x24 from Ultegra triple? Or?? I don't want to go with SRAM as shifting is so different from Shimano that I think I will have problems with two sets of shift systems. Suggestions.

Jim Paul
76 years old and still wanting to climb hills.
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Old 01-06-20, 04:45 PM
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It's expensive but a sugino OX 901D uses 110/74 bcd rings so you can get pretty small on the inner chain ring (down to a 24) and it's 10/11 speed compatible.
Soma sells them and so do other vendors:

https://www.somafabshop.com/shop/pro...4?category=761

There's a lot to be said for a small inner chain ring for climbing. It's too bad that triples have gone out of style.
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Old 01-06-20, 04:54 PM
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Originally Posted by JimPaul View Post
Want to build or order a gravel bike with really low gears. Current road bike is a 2014 Madone with 36x11 10 speed rear and 36x22 front chain ring setup from small and middle chain ring of Deore XT triple. The low from a 42x11 rear cassette and 11 speed Shimano GRX 46x30 front chain rings are too big for what I can handle in hills. Don't know if there are chain rings for GRX crank smaller than 46x30. Can't find the specs. Not sure of best alternative front crank. 36x22 with another Deore XT triple? 38x24 from Ultegra triple? Or?? I don't want to go with SRAM as shifting is so different from Shimano that I think I will have problems with two sets of shift systems. Suggestions.

Jim Paul
76 years old and still wanting to climb hills.
30front and 42rear is too big of a low gear?
Are you sure that's what you want?
I applaud your desire to climb hills, but gearing much below one-to-one is usually not ride-able.
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Old 01-06-20, 08:59 PM
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Sugino OX 901D will work. Maybe my old triple OK.

Originally Posted by bikemig View Post
It's expensive but a sugino OX 901D uses 110/74 bcd rings so you can get pretty small on the inner chain ring (down to a 24) and it's 10/11 speed compatible.
Soma sells them and so do other vendors:

https://www.somafabshop.com/shop/pro...4?category=761

There's a lot to be said for a small inner chain ring for climbing. It's too bad that triples have gone out of style.
I think I can use my old 10 speed triple crank, granny and middle chain ring only. Will end up with 39x24 front chain ring, maybe with a shim if need be to make 10 speed system work with an 11 speed shifter.
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Old 01-06-20, 09:11 PM
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The shimano road triple was a bit weird since it was a 130/74 bcd crank. So you can run a 39/24 (you can't go smaller than 24 on the inside and a 39 in the middle) but that is a big drop. The Sugino may give you better gear ratios since you can run a smaller chainring on the outside.
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Old 01-06-20, 09:18 PM
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I'm 66 and find I can't pull the gears I used to. In fact I had to reevaluate the whole gear range and admit to some limitations. First I acknowledged that I wouldn't need a 55 tooth sprocket up front. In fact I couldn't pull a 42x11 unless I was falling off a building. I wanted to use all the gears on my 10 speed cassette rear. I found that about 33 teeth was as big as I could go and still pedal that 11 on the back going downhill or down wind. Since I don't race anymore I don't need those pie in the sky sitting in a pace line doing 28mph waiting for the sprint to the finish gearing. Now I ride for exercise and good health. I do ride as fast as I can go but my bicycle's are geared much lower so I get my money's worth from every gear on them. I like 11x34 MTB cassettes, Shimano MTB Shadow tech rear derailleurs. I will use any derailleur that will shift the front properly. My main bike has an old Suntour front derailleur from the early 1980's that shifts the two speed front end flawlessly. For real low gearing I use MTB JIS cranks at 180mm, I'm 6ft5in tall. MTB cranks will allow you to use very small front sprockets. My recumbent has a 26 tooth low going to that 34 tooth rear. Low enough for everything I've tried it on. There is such a thing as too low geared where the ground speed is so slow that your steering flops from side to side and it is hard to keep the bike up. If I want real low gearing MTB components are made for that. Road triples usually cant carry those real small front chainrings. I still chase down people on the bike trail and heaven knows plenty pass me up but it is all good. Keep riding.
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Old 01-06-20, 09:40 PM
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Originally Posted by bikemig View Post
The shimano road triple was a bit weird since it was a 130/74 bcd crank. So you can run a 39/24 (you can't go smaller than 24 on the inside and a 39 in the middle) but that is a big drop. The Sugino may give you better gear ratios since you can run a smaller chainring on the outside.

I will definitely look at the Sugino more closely. However, I ran the Ultegra 39/24 for years with the triple. It shifts OK, certainly not super smooth. With the 42 tooth large rear cassette wheel, I can go to a 39/26. This will help. I also have a 38 that will work on the Ultegra triple. Lots of options. Having said that, the Sugino looks like a clean crank. I would likely go with a 38x26.
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Old 01-06-20, 09:57 PM
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I built a gravel bike/rigid drop bar mountain bike with mountain bike derailleurs: SLX 34/24T crank and 11-42T 11-speed cassette. The lowest gear is as low as I can manage and stay vertical.

White Industries makes (very expensive) cranksets that allow you to put on almost any combination. I think they go as low as 24T as well.

I am building up a touring bike with the white industries crankset with 46/30T chainrings and an 11-42 cassette with a mountain derailleur. I'm using microshift bar end shifters. That might be low enough for you, but the newer XT/SLX rear can go to 48 (or 51 if you go 12-speed).
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Old 01-08-20, 11:35 AM
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If you want off the shelf, the GRX combo can go pretty dang low. 48/31 up front and pretty much any size XT 11 speed out back the biggest being an 11-46.

I should be getting my GRX crankset tonight and that will put me at 48/31 up front and a custom 14-34 out back, so a couple of more options for keeping the spin going on climbs.
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Old 01-12-20, 05:40 AM
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This old school 3x9 solution works on a wide set of frames and is cost effective. It features a 48, 36 & 22 crankset with a 11-32 rear cassette. No reason to go lower than that.

I installed a Shimano Deore “Trekking” crank-set with 48, 36 and I installed a 22t small chainring. This was matched to a 11-32 nine speed cassette. Tiagra STI “brifters” and a front derailleur for triple were installed. Sora 3x9 shifters would also work. A Deore SGS rear derailleur completes the drivetrain.





These 2x11 drivetrains also provide low gearing;

2x11: 48/31 & 11-34





2x11: 46/33 & 11-36


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Last edited by Barrettscv; 01-12-20 at 05:46 AM.
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Old 01-12-20, 06:54 PM
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Originally Posted by Barrettscv View Post
This old school 3x9 solution works on a wide set of frames and is cost effective. It features a 48, 36 & 22 crankset with a 11-32 rear cassette. No reason to go lower than that.

I installed a Shimano Deore “Trekking” crank-set with 48, 36 and I installed a 22t small chainring. This was matched to a 11-32 nine speed cassette. Tiagra STI “brifters” and a front derailleur for triple were installed. Sora 3x9 shifters would also work. A Deore SGS rear derailleur completes the drivetrain.





These 2x11 drivetrains also provide low gearing;

2x11: 48/31 & 11-34





2x11: 46/33 & 11-36


Barretscv you have great looking low gear systems. The older style the gearing system the cheaper it is. Therefore older style 7 and 8 speed equipment is even cheaper than the 9 speed stuff. a 3x7 or 3x8 has plenty of range for riding most anywhere. I do like the 10 speed cassettes and they are coming down in price due to the changes to 11 and 12 speed systems. Choosing the right gearing for your riding is much the harder job than procuring it.
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Old 01-12-20, 07:35 PM
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Originally Posted by tallbikeman View Post
Barretscv you have great looking low gear systems. The older style the gearing system the cheaper it is. Therefore older style 7 and 8 speed equipment is even cheaper than the 9 speed stuff. a 3x7 or 3x8 has plenty of range for riding most anywhere. I do like the 10 speed cassettes and they are coming down in price due to the changes to 11 and 12 speed systems. Choosing the right gearing for your riding is much the harder job than procuring it.
I agree that a triple can provide an excellent range on a 7 speed freewheel or 8 speed cassette. I completed the 150km Dairyland dare (7000 ft of climbing) with this drivetrain;

3x8: 48/36/26 & 12-28


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Old 01-19-20, 06:40 PM
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Originally Posted by SCTinkering View Post
If you want off the shelf, the GRX combo can go pretty dang low. 48/31 up front and pretty much any size XT 11 speed out back the biggest being an 11-46.

I should be getting my GRX crankset tonight and that will put me at 48/31 up front and a custom 14-34 out back, so a couple of more options for keeping the spin going on climbs.
Did a Gran Fondo on this setup last weekend and while the distance tired me out, non of the climbing did. That said I still haven't done anything like a steep climb on it yet. maybe tomorrow for that.

One thing I have discovered though, it kinda sucks for ZWIFT. Funny thing the fake world I can't generate any reasonable wattage on the biggest combo (48/11 - Trainer has a 11-30 cassette on it.)
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Old 01-23-20, 07:01 PM
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I just set up my wife's gravel bike in a 1x configuration with a 44T chainring in the front and a 10-50 cassette in the back using some of the new SRAM AXS stuff. Easy deal to drop that front chainring down. I think you could go as low as a 32 but I'm not quite sure about that, but could go lower.
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Old 01-24-20, 08:49 AM
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Originally Posted by SCTinkering View Post
Did a Gran Fondo on this setup last weekend and while the distance tired me out, non of the climbing did. That said I still haven't done anything like a steep climb on it yet. maybe tomorrow for that.

One thing I have discovered though, it kinda sucks for ZWIFT. Funny thing the fake world I can't generate any reasonable wattage on the biggest combo (48/11 - Trainer has a 11-30 cassette on it.)
That doesn't sound right. I have a 50/11 on my trainer setup and I can barely move the pedals on level ground in Zwift. Even at 50/13 I can get 600-800 watts if I'm standing. What trainer do you have? Did you change the "trainer difficulty" setting?
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Old 01-24-20, 10:58 AM
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It's a combo of the trainer (Kinetic R1) wasn't calibrated (bad firmware update re-flashed) and Zwift doesn't work well without a decent FTP number. Guessing based on age, weight and max HR doesn't work. So I need to plug in a realistic ballpark FTP and actually do an FTP to get the real number.

I didn't touch the trainer difficulty, but I get the feeling that I won't have zwift sorted until the trial period is over.
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