# Chainring or Sprocket?



## JPBoothy (21 May 2018)

Hi All, 
I have SS with a 46t chainring and a 16t Sprocket but, I think my knees are starting to crave an easier life. I changed from an 18t to a 16t over 12mths ago as I was starting to spin out once up to speed but, it is now the resistance when starting off that's begining to take its toll, especially if climbing. Would changing down to a 42t chainring make much of a noticeable difference?


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## dave r (21 May 2018)

I'd just put an 18 tooth sprocket on, my fixed runs 44x18, about a 64-65 inch gear, which is spinny.


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## Ajax Bay (21 May 2018)

JPBoothy said:


> Would changing down to a 42t chainring make much of a noticeable difference?


Going from 18t to 16t gave you an 11% longer gear. Going from 46t chain ring to a 42t would mean a 9% shorter gear.
Would seem much easier (with negligible 'difference') just to go back to the 18t sprocket.


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## Milkfloat (21 May 2018)

Sprocket much cheaper, but you may need to lengthen chain, if you go chainring then no new chain needed.


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## Ian H (21 May 2018)

I have ridden 43x17 almost invariably on fixed. Nowadays I'm more likely to stick to 43x18. 

Learning how to spin and the resultant improvement in smooth pedalling technique is one of the reasons for riding fixed. I'm happy up to around 150rpm cadence; used to be a lot higher when I was younger.


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## dave r (21 May 2018)

Ian H said:


> I have ridden 43x17 almost invariably on fixed. Nowadays I'm more likely to stick to 43x18.
> 
> Learning how to spin and the resultant improvement in smooth pedalling technique is one of the reasons for riding fixed. I'm happy up to around 150rpm cadence; used to be a lot higher when I was younger.



I'm the same, happy up to 150rpm, used to manage a bit higher when I was a youth.


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## JPBoothy (21 May 2018)

I 'sort of' grasp the different Gear Inches calculations but, the distance per crank revolution doesn't really tell me how it's going to actually feel to drop down a few teeth. I was onIy thinking about a 42t as I know that when I had one of my previous old school bikes with a 52/42 double I used to favour the 42t so much that the 52t was hardly ever used. I see the sense in changing the cheaper sprocket though, so I'll probably give that a go. I can't put my old Shimano one back on as it was knackered but, I have been pleased with the quality of the Sturmey Archer 16t I replaced it with (nice clicking sound to it) so I'll look for one with 18t and see how i get on. 

Thanks for the advice everybody it is always appreciated


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## mjr (22 May 2018)

Milkfloat said:


> Sprocket much cheaper, but you may need to lengthen chain, if you go chainring then no new chain needed.


KMC B1 is £4 from a local bike shop. SA sprockets are similar. I think decent chainrings are more than £8 but I could be wrong. I'd change the sprocket and fit a new chain.


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## simongt (23 May 2018)

Ian H said:


> I'm happy up to around 150rpm cadence;


How fast - ? !  Although I've never ridden 'proper' fixed, I have attempted in the past to spin as fast as my wee legs will allow on a geared bike in the right circumstances. But I've never achieved more than about 80- 90rpm because it seemed that my legs wouldn't respond to my brain saying 'spin faster'.
So how do you folk manage 150rpm then - ?


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## Milkfloat (23 May 2018)

simongt said:


> So how do you folk manage 150rpm then - ?



For me, downhill. I find the trick is power through rather than letting your legs be passengers.


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## dave r (23 May 2018)

simongt said:


> How fast - ? !  Although I've never ridden 'proper' fixed, I have attempted in the past to spin as fast as my wee legs will allow on a geared bike in the right circumstances. But I've never achieved more than about 80- 90rpm because it seemed that my legs wouldn't respond to my brain saying 'spin faster'.
> So how do you folk manage 150rpm then - ?



Keep it smooth and keep pressure on the pedals, keep pushing the pedals round don't let the pedals turn your feet.


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## Ajax Bay (24 May 2018)

Ian H said:


> I'm happy up to around 150rpm cadence;


I can confirm after @Ian H 's 3+ pints last night, those little pistons were achieving a remarkably high cadence (on fixed) down the first downhill. Masochism.


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## JPBoothy (24 May 2018)

mjr said:


> KMC B1 is £4 from a local bike shop. SA sprockets are similar. I think decent chainrings are more than £8 but I could be wrong. I'd change the sprocket and fit a new chain.


Where is this super cheap LBS? I have scoured ebay and googled until my eyes were crossed but, I have never spotted chainrings for anywhere near £8.


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## Ajax Bay (25 May 2018)

Read @mjr post again.
But since you ask: https://www.spacycles.co.uk/m2b0s185p0/Parts-and-Accessories/Components-Gears-Chainrings-Clearance


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## smutchin (25 May 2018)

simongt said:


> So how do you folk manage 150rpm then - ?



Practice. I used to ride fixed on the commute every day and soon developed the ability to spin comfortably at 120rpm on the flat. 150rpm downhill is fairly normal - but I find it's more a case of your legs trying to keep up with the speed the cranks are spinning at, rather than actively pushing.


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## rogerzilla (25 Aug 2018)

170rpm is ok in short bursts (35mph on a 70" gear) but you won't be putting in any power at that speed unless you're really, really good.

I choose a gear so I don't have to drag-brake on any foreseeable descents, and let the climbs worry about themselves. When I used to ride evening "10"s, I'd be riding out to the start on a 48 x 14 and it was quite manageable, even steep bridge approaches.


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## silva (7 Apr 2019)

I also don't get how someone is able to spin such high rpm. Short legs? Short cranks?
When I went 35-40km/h with my fixed gear of 48/16, I almost have to hold my legs up as to not resist the pedals movement, and when I do hold them on it's like I'm dancing on my saddle.
And most of all, it just feels so useless, lotsa energy for little more speed.
At least, that was my impression, if it is scientific, I don't know. :P


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## dave r (7 Apr 2019)

silva said:


> I also don't get how someone is able to spin such high rpm. Short legs? Short cranks?
> When I went 35-40km/h with my fixed gear of 48/16, I almost have to hold my legs up as to not resist the pedals movement, and when I do hold them on it's like I'm dancing on my saddle.
> And most of all, it just feels so useless, lotsa energy for little more speed.
> At least, that was my impression, if it is scientific, I don't know. :P



I'm comfortable up to around 150rpm, above that my little legs struggle to keep up.


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## Ajax Bay (7 Apr 2019)

dave r said:


> I'm comfortable up to around 150rpm


If you look ^^^, Dave, you will see your comment is consistent with yours of 11 months ago @silva has resurrected an old thread.


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## silva (7 Apr 2019)

Ajax Bay said:


> If you look ^^^, Dave, you will see your comment is consistent with yours of 11 months ago @silva has resurrected an old thread.


Shouldn't his rpm have dropped abit since he's a year older now?


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## dave r (7 Apr 2019)

Ajax Bay said:


> If you look ^^^, Dave, you will see your comment is consistent with yours of 11 months ago @silva has resurrected an old thread.



Looks like I shall have to stop multitasking and concentrate fully on what I'm doing.


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## dave r (7 Apr 2019)

silva said:


> Shouldn't his rpm have dropped abit since he's a year older now?



My RPM hasn't changed a lot since I started riding fixed, about 1989, what's happened is I've got more comfortable spinning it up.


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