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Anyone using a 46/30T crank on a road bike?

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Anyone using a 46/30T crank on a road bike?

Old 06-11-19, 05:31 AM
  #376  
Barrettscv 
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Originally Posted by wgscott View Post
We can now add Shimano to the list: FC-RX600-11

https://gravel.shimano.com/en/components/crankset/

The higher-tier one in their new gravel line is 48/31T. (WTF?)

They say that these new cranks change the chainline by 2.5mm, and that requires their new derailleur(s). (also, WTF?)
The chainline on the RX-600-11 is optimized for modern disc brake bikes with 142mm thru-axles. It's possible that this crankset will have chainline related cross-chaining issues if installed on a rim brake bike. The big-big combination would be problematic.

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Old 06-23-19, 08:15 AM
  #377  
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Originally Posted by Barrettscv View Post


The chainline on the RX-600-11 is optimized for modern disc brake bikes with 142mm thru-axles. It's possible that this crankset will have chainline related cross-chaining issues if installed on a rim brake bike. The big-big combination would be problematic.
I have a White Industries crank with a wider chain-line along with a 135mm hub in the rear. Works fine, even on big-big (and my rear big is 36T on one wheelset, 34 on the other). My bet is it most likely will work.

Anyway, the point was that it is another option (and that this is now main-stream enough to be an option with Shimano, FSA, etc.), not that it will work with any setup.
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Old 06-23-19, 08:46 AM
  #378  
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Originally Posted by wgscott View Post
I have a White Industries crank with a wider chain-line along with a 135mm hub in the rear. Works fine, even on big-big (and my rear big is 36T on one wheelset, 34 on the other). My bet is it most likely will work.

Anyway, the point was that it is another option (and that this is now main-stream enough to be an option with Shimano, FSA, etc.), not that it will work with any setup.
The Shimano RX-600-11 Gravel crankset is an excellent solution for disc brake bikes with thru-axles. Rim brake bikes with 130mm dropouts, the most common specification, might have drivetrain issues. Shimano recommendations the matching derailleur. These are important details that purchasers need to consider.
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Old 06-26-19, 10:27 AM
  #379  
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Yep. Just put a Ritchey Logic compact (94mm bcd) on my Merckx Team SC. Works just right with a Campy 102mm BB, and weighs less than most modern cranks!

But it did take a while to get over the "that's not appropriate for a pro race bike" thing and give my self the gearing I need.
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Old 07-05-19, 05:09 AM
  #380  
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Maybe a simpler solution is to just substitute the big ring 50 tooth chainring for a 46 T. I did that on my Cannondale that originally came with A 50/34. I needed to lower the front derailleur a tad, but with the 46 big ring I find I spend 95% of the time in the big ring in hilly Virginia.
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Old 07-05-19, 05:35 AM
  #381  
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You can run a compact on a vintage bike as well with the right crank such as a TA cyclotourist or a Stronglight 99. I recently built up an early 70s Motobecane Grand Record with a TA crank. The original gearing was 52/40 with a 14-26 5 speed rear freewheel. That provided a low of 41.5 gear inches. I built the bike up with 46/36 rings and a 14-28 5 speed rear freewheel which gave me a knee friendlier 34.7 gear inch low. I should search around for a 32 inner and run this as a 46/32.


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Old 07-18-19, 09:33 AM
  #382  
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Hello everyone- I just found this Forum because of a Google search I did"anyone using 46/30T on road bike?" I have a Cannondale Synapse Carbon 4 that uses an FSA Energy compact 50/34T 110 BCD 5 bolts(ABS I guess) It has the BB30 and SRAM Rival group-set. My dream was the adventure crankset by FSA 46/30 but bike shops said it couldn't be done and/or if possible the crank was $350 Canadian.

So instead today I am spending too much money to get a new rear SRAM Rival cassette 11-36 to give me 4 more teeth-then need a new derailler to fit the 4 extra teeth and a new front chainring since the original is a bit worn. This is a change from my 11-32 that came with the bike.


I can go up hills the way it is-we have mountains and such -mostly I stay away from the silliness like riding to Whistler(ski area). The problem is my heartrate goes up to around 175-185 on hills. My max. heartrate should be 165.


I wondered if I could just switch out two rings and put on a 48/32T combination to my existing crankset. If they are 110 BCD it should work? LBS said maybe the smaller ring will cause an issue by rubbing the front derailler and or chainstays.

Sorry for the essay. Anyone have any ideas.

Thanks
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Old 07-18-19, 09:44 AM
  #383  
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@chef09

The SRAM 11-36T might work fine with your existing derailleur, with just a B-screw adjustment. Then Wolf-tooth makes an adaptor, if that (or putting in a longer screw for $0.75) isn't enough. My Shimano mid-cage Ultegra derailleur handles the SRAM 11-36T cassette without issue.

I think the least expensive option for the front (US$ 150) will now be the new Shimano GRX 46/30T crankset.

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Old 07-18-19, 09:50 AM
  #384  
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Originally Posted by Timdugan View Post
Maybe a simpler solution is to just substitute the big ring 50 tooth chainring for a 46 T.
If your goal is just to change the gear spacing, rather than the lower range, that would work, but if you want a smaller small chain-ring to get lower hill-climbing gearing, I don't see the advantage.
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Old 07-18-19, 09:51 AM
  #385  
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I was running Absolute Black 46/30 chainrings on an Ultegra crank but they have gone away due to shifting performance issues. It is a shame because the oval rings feel great to pedal.

An Easton EC90 SL "Cinch" crank with Easton 46/30 gravel rings in going on. I'm currently waiting for the proper spacers to arrive.







-Tim-
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Old 07-18-19, 10:04 AM
  #386  
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I have 44/24 on the sugino ox601d. 46/24 was possible if I used spa cycle rings, but then requires very precise adjustments. Ox601d and ox901d are discontinued and leftover stock is on sale on the sugino website. The splines slip though so you need to use the light loctite 222 in the compression bolt or else it will come loose. Blue loctite is too strong and you'll have to heat it with a torch to melt the threadlocker. The newer ox2-901d has revised splines similar to Shimano splines. The new compression bolt uses Shimano socket head. But with the old compression bolt, I tapped it with left hand threads so thieves can't get it off. I don't think you can tap the new compression bolt.
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Old 07-18-19, 02:49 PM
  #387  
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Thanks so much. The unfortunate thing is -the bike shop already ordered and received the new rear derailleur. Because they don't stock it, I doubt that they will be willing to 'send it back'. I will try. I will also look for the Shimano 46/30 crankset. It's the small ring that I want and the 46 is to accommodate the 'keeping the same jump' between front rings. I'm just leaving for the shop now. Hopefully they will try to make the original derailleur work to save me some dough but SRAM says that this stock piece maxes out at 34T for the rear cassette. Based on that recommendation I think the LBS will err on the side of caution. (and selling a part that they special ordered .
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Old 07-18-19, 03:55 PM
  #388  
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I have a Shimano RD4700 rear derailleur with 12-34T custom 10 speed cassette that I mixed and matched myself. With a 44/24T front double crank. This gives me a 519% range = 44/24*34/12. The lowest gear gives me 24/34 = 0.706 ratio. The RD4700 is rated for up to 34T cassette and a 41T chain wrap, but I'm using 42T wrap and have tried up to 44T wrap, if the small-small combination has the pulleys dragging on the chain, but it doesn't matter since I am never on the small-small.

Your 11-32T with 50/34T is = 50/34*32/11 = 428% range. Your lowest gear gives you a 34/32 = 1.0625 ratio.

If you increase the rear cog to 36T, then you get at the lowest 34/36 = 0.944 ratio, or a 1.0625/0.944 = 12.5% drop, which feels like 1 gear lower. Also the range changes to 481%.

However, if you're really having trouble on the lowest gear, you might want at least a 30% drop, or a 0.81 gear ratio, which feels more like a 2 gear drop.

You currently have a 16T jump on your front chainring. I've done 20T jump without any problems, as long as you install a chain catcher and fiddle with the FD angles and cable. I was also able to do 22T jump but was more complicated to adjust. So if you want to keep a 50T then you could match it with 30T for a 20 jump. However, 110mm BCD will only allow you to go as low as 33T, which you can get from TA or spacycles. If you want to go lower than 33T, the FSA with 30T has 80mm BCD but I had asked before and they don't make any other sized chainrings for 80mm. The minimum teeth physically possible for 80mm BCD is 26T, so if you have a CNC machine, you could take a 26T with 74mm BCD and drill out new holes at 80mm. Otherwise, get a crank with 110/74mm and your minimum possible teeth drops to 24T.

If you drop your small chainring to 30T and keep your max 32T rear cog, you get a 0.9375 ratio. It's practically the same as changing to a 36T max rear cog. But the benefit of changing the front chainring instead is having closer cassette spacing. My custom mixed cassette has big spacing at the bottom and small spacing at the top. 34, 28, 24, 21, 19, 17, 15, 14, 13 ,12. Some of the Shimano cassettes don't mix well though. I have another thread explaining my experience attempting to mix 4 different sets of Shimano 10 speed cogs.

With an 18T jump in chainrings, if I increase the chainring spacings by inserting 0.1-0.2mm shim washers, I can go up to 8th gear on 10 speed while on the inner chainring before the chain starts to rub on the outer chainring. With a 20T jump, I can only go up to 7th gear. But 7th gear on the inner chainring for me is somewhere between 2nd and 3rd on the outer chainring. So there is only 2 usable gears overlapping. So I have 15 unique gears in a linear shift.

With the small-small combination with 24T chainring, the chain will start rubbing on the chainstay, but since I'm never on small-small because I can only get up to 7th gear on the small chainring, it isn't a problem for me. For quick estimate of chain clearance, you can take 1.0" x 25.4mm / 3.1415 = 8.09mm difference in chainring diameter for every 2 teeth, since 2 teeth is a change of 1.0" in circumference or chain length.

Last edited by tomtomtom123; 07-18-19 at 04:28 PM.
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