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Chain ring question

by bjk
Sat, Sep 12, 2020 12:27
11

I presently have a Shimano compact 50-34  with a 12-25 cassette.. Also running a small rear cage... Can I only replace the 50 large ring to a 52 for more top end speed ?  Any suggestions ?

Thanks

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11 comments

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pablo | 3 years ago
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Guy lives in Florida so very flat a 52 would be perfect. The 11-25 confused me at first because it's not something that I'd run even on a compact but in Florida..... I tried a 52 sub compact a few years ago and went away from it but recently got a bike with it and 11-30 cassette on the back and am loving it now. I'm pretty fit this year which helps and am setting PR's on my local Cat 3/4 climbs. I haven't got massive power but spinning a high cadence let's my heart rate run away spinning a lower cadence 75-80 average works well for me. I get high cadence is less fatiguing and i can understand the logic on multiday events but on a 2-4 hour ride I don't really get leg fatigue much anymore

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bjk | 3 years ago
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I recently upgraded my wheels and I get up to speed quickly...so yes I'll put the put the 11-25 cassette on.  {I wasn't thinking..basic fix}.. and quessing from my experience with the new wheels (Roval CLX 50 Rapides) I'll want to swap out the 50 to a 52 chainring  pick up a little more mph...  So I'm back to the same question..will the 52 be compatable with the 34 along with the short derailleur ?    Thanks

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don simon fbpe replied to bjk | 3 years ago
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Larger chainrings will affect chain length.

Rear mech affected by cassette range (not chainrings).

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njblackadder replied to bjk | 3 years ago
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I would wager that you will actually go slower attempting to push a 52 x 11, rather than a 12t sprocket. 52 x 11 is a gear only the pros, or those of similar ability, can actually 'use'. Even 52 x 12 is a huge gear. Fitting a more 'sensible' cassette with usable ratios in the middle, rather than something that is really of no use would be my way of doing it, but each to their own. As long as you are happy, that is the most important aspect. All the best with it.

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Nick T | 3 years ago
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You won't gain top end speed, you will just have to spin less and create more torque with your legs for the equivalent speed you currently ride at

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don simon fbpe | 3 years ago
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Isn't the rule of thumb no more than a 16 tooth difference between chainwheel tooth counts?

I'm sure a larger difference could be achieved, but would need to ensure pick up points on larger chainwheel are designed to function in that way.

I'm quite sure that folks will have a larger than 16 tooth jump that they've got to work perfectly.

Have a read of, the dearly missed, Sheldon to get your head around derailleurs: https://www.sheldonbrown.com/front-derailers.html

If you're looking at upping top speed, wouldn't looking at 11t at the back be the quickest, easiest and cheapest option?

Edit: Yes you can put a 52t chainring on, but would be advised to increase the the 34t to 36t, thus maintaing that 16t difference. This wouldn't affect rear mech.

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bjk replied to don simon fbpe | 3 years ago
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Yes !  the 11t would be the first thing to do...I had a senior moment....and I was not aware of the 16 T rule.....so I guess a standard or mid compact may be on the wish list ...hoprfully I'll be okay with 11-25...Thanks

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AlsoSomniloquism replied to bjk | 3 years ago
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Just be aware of the length of chain. Two sprocket increase is probably counted for but it might be tight depending. 

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bjk replied to AlsoSomniloquism | 3 years ago
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Thanks ...for all of your responses ....they helped get me get back on track...I'm putting  on the 11-25   cassette and  at 74 I'm just going to enjoy my new  birthday present wheels.....I usually ride everyday but the Florida summer thunder showers have kept me indoors for a couple of days....and I have to stop watching the daily news....people are having a really tough time etc etc...and it has affected me...riding is my enjoyment , release and outlet !!!  

Be safe ! and Thanks.........

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Simon E replied to bjk | 3 years ago
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50x11 should be a big enough gear for most people, that is a bigger gear than 52x12.

SS rear derailleur may take 28 cassette (the limit depends on which one you have) though total capacity of front+rear is also important.

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kil0ran replied to don simon fbpe | 3 years ago
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MTB derailleurs happily handle a 22T front difference so it would probably be ok, just not perfect. And being in Florida I'd imagine it's mostly flat so you'll spend most time in the big ring

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