Author Topic: What is the ideal ratio transmission  (Read 2388 times)

pavel

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Re: What is the ideal ratio transmission
« Reply #15 on: January 09, 2018, 01:23:30 AM »
So for you Pavel, a transmission 41X17 is ideal even bike loaded ..

But what about climb a pass ? ..

You seem in very good physical condition, is not it ?

That was the ratio that I used when I cycled from North Carolina to Texas in 2012 with my daughter.  I was carrying between 45 and 60 pounds on that trip, depending on food and water.  Virginia has some very impressive climbs, the most elevation gained of any state on the Trans-America tour, and I was in terrible shape and for weeks on end the temps were over 38-42 degrees with the horrid humidity that the South Eastern US has in summer.

That ratio was a guess on my part but it turned out perfect.  Not because my legs and body were up to the task, but rather by virtue of the fact that I can't seem to go in a straight line well enough under about 3 miles per hour, so a lower ratio turned out to be undesirable for me for that reason.  Both Bianca and I agreed that being that being macho and never pushing the bike up the hill was not something that worked for us. 

So in summation, I'd have to spin too fast with a lower ratio, (and I don't like to go over about 110 rpm) and I don't like to weave like a drunk, so we'd get off our bikes and push quite frequently on the worst of the climbs.  I think that getting off and pushing increased our daily miles, not that we cared about mileage for mileage sake at all, due to the change up the muscles got.  We normally did between 70 and 130 km each day and boy oh boy some days were tough.

I should mention that I was in very bad shape.  I was suffering from  stage four follicular lymphoma  and had about 8 kilos worth of a tumor  on the right side of my belly which often meant no sleep for days.  I had to stop to vomit a lot of the time. Strange .... that it was very  best 54 days of my life.

http://way-word-way.com/page/6/

julio

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Re: What is the ideal ratio transmission
« Reply #16 on: March 01, 2018, 02:06:22 PM »
I thought i heard chainring is very strong and can easily endure thousands kilometers .. but how many thousands exactly ?

mickeg

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Re: What is the ideal ratio transmission
« Reply #17 on: March 01, 2018, 05:59:53 PM »
I thought i heard chainring is very strong and can easily endure thousands kilometers .. but how many thousands exactly ?

A worn chain will wear it faster. 

Dirt and grime on the chain will wear it faster. 

A chainring with softer material will wear faster, I paid $8 USD for my chainrings so they are pretty soft. 

A heavier rider will wear it faster.

There is more tension on the chain with smaller chainrings, so a smaller chainring will wear faster.

I marked my chainrings so that I always put the chain on the chain ring the same way, I cut a small notch in one tooth that I always make sure I use a link on that tooth that has outer plates.  That extends the life some.
https://www.sheldonbrown.com/chain-life.html

A chainring that you can reverse will double the distance.

There probably are a dozen other factors I did not think of.

In other words, it varies.

julio

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Re: What is the ideal ratio transmission
« Reply #18 on: March 01, 2018, 06:09:03 PM »
$8 usd for a chainring   :o   so cheap !

All single chainrings are not reversible ? 

mickeg

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Re: What is the ideal ratio transmission
« Reply #19 on: March 01, 2018, 09:09:27 PM »
$8 usd for a chainring   :o   so cheap !

All single chainrings are not reversible ?

I just checked, they are up to $10.18 USD.  Five years ago I paid $8.

It had never occured to me to try it reversed.  There is a slight recess on one side of the chainring where the chainring bolts or nuts slip into.  You probably could ride with it reversed, although it was not designed for that purpose and the bolt or nut would stick out slightly.  The ones I am citing are flat, so chainline would be nearly the same if you reversed it.

John Saxby

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Re: What is the ideal ratio transmission
« Reply #20 on: March 02, 2018, 05:33:34 AM »
FWIW, I bought my 36T Surly stainless ring in Manhattan for USD30 a few years ago. I wanted the stainless item so that I could easily fit a Hebie Chainglider. It is reversible. We were visiting NY anyway, and since it was about $15 cheaper than it would have been in Ottawa, it seemed like a good deal to me.

It seems indestructible--no obvious (to me) signs of wear. I had heard/read that Surly's rings can be less than perfectly round, so creating a tighter-than-usual tight spot on the chain. This one creates a tight spot, but not unusually so.

I do have a 38T Surly ring in good nick, with about 4500 kms on it, if anyone wants one.

RobertL

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Re: What is the ideal ratio transmission
« Reply #21 on: March 02, 2018, 07:18:39 AM »
My original Thorn 38T was worn at around 10,000 miles. My bike guru advised rotating the chain ring 90 degrees at every change of the chain, and then reversing the chain ring. The theory is that the wear is associated with the power stroke and in this manner you spread exposure to this across the whole ring.

martinf

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Re: What is the ideal ratio transmission
« Reply #22 on: March 02, 2018, 08:38:52 AM »
I thought i heard chainring is very strong and can easily endure thousands kilometers .. but how many thousands exactly ?

My experience:

- minimum 2400 kms for a 34T ring used as a single (DualDrive hybrid hub/derailleur gearing), with quite a lot of use in wet/mucky conditions.
- maximum so far 20000 kms for a 50T outer ring used on a derailleur bike used mainly in clean, dry conditions.
- a 44T 1/8" width single ring used without a Chainglider on an all-weather hub gear commuter lasted 17000 kms.

All these examples are without reversing the chainring.

I expect to get much better wear from my bikes fitted with Chaingliders, as the transmission stays much cleaner.

When possible, I also now fit Surly stainless-steel chainrings, which should help reduce wear (steel is harder than most aluminium alloys). The Surly chainrings are also reversible, unlike most of the other chainrings I have. And they fit the Chainglider better than my old TA aluminium alloy rings.

julio

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Re: What is the ideal ratio transmission
« Reply #23 on: March 02, 2018, 12:39:59 PM »
Surly chainring seems to be a good choice, i remember Dan advised me this one too, but unfortunately it is only in silver color, i prefer black ! as the Thorn reversible chainring.. but doesn't matter, for travel a long distance better to have something strong and reliable   :)

As well, can i adapt the Surly chainring without difficulty ? with the same chainring bolts ? (currently i have on my bike the Thorn reversible chainring)

geocycle

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Re: What is the ideal ratio transmission
« Reply #24 on: March 02, 2018, 12:48:56 PM »
Surly chainring seems to be a good choice, i remember Dan advised me this one too, but unfortunately it is only in silver color, i prefer black ! as the Thorn reversible chainring.. but doesn't matter, for travel a long distance better to have something strong and reliable   :)

As well, can i adapt the Surly chainring without difficulty ? with the same chainring bolts ? (currently i have on my bike the Thorn reversible chainring)

You might need spacers for the chainring bolts as the Surly is quite a lot thinner than the Thorn. These also help with getting it central on the spider.
 

mickeg

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Re: What is the ideal ratio transmission
« Reply #25 on: March 02, 2018, 04:58:33 PM »
.... I had heard/read that Surly's rings can be less than perfectly round, so creating a tighter-than-usual tight spot on the chain. This one creates a tight spot, but not unusually so....

On an IGH bike when I put on a new chainring, I usually leave the chainring bolts only slightly tight.  Turn the crank and look for tight spots.  There often is a bit of space between the chainring bolts/nuts and the chainring or crank spider.  I often find that shifting the position of the chainring slightly can make a big change in chain tightness.  Sometimes I have to even loosen up the bolts slightly to be able to shift the ring on the spider, I want them tight enough to hold position but loose enough that if I tug on the chain they can shift position.  When I get it the way I want it (which is never perfect but better than when I started) I tighten up all the bolts.

Derailler bikes, does not matter.  Just put the rings on and tighten.


..., but unfortunately it is only in silver color, i prefer black ! as the Thorn reversible chainring.. ..

Both the chainring and the bashguard in the photo were originally silver, I sprayed them black.  Lighting for the photo was not very good but the spray job does not look bad.

That bash guard started off as a 52T chainring, I cut the teeth off of it, filed the cut marks till it was round and sprayed it.



Andre Jute

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Re: What is the ideal ratio transmission
« Reply #26 on: March 02, 2018, 05:33:43 PM »
I like the Surly chainrings, though in my present setup, which requires a dished chainring to straighten the chainline, I can't use them. However, on the way to the Surly, I had a cheap steel ring and cranks (Amar, from India, supplied by a German dealer) fitted on a new bike as a placeholder until I decided which cranks with more class I wanted. Eventually it took me years to find cranks that weren't aesthetically repulsive, and at this point I fitted the Surly stainless ring.

I was hugely impressed with the service the steel ring gave.

Because of changes in other components, I had to take off the Surly and fit a dished steel ring (cost $9 in China...) to preserve the chainline and about 5K later I'm again very impressed: the ring is barely marked and looks like it will march on forever.

Both these steel rings are black. So, if black is aesthetically important to you, you can save some money and get a good steel ring. Or you can have the Surly blackened by the platers and anodisers in your town (use the yellow pages); when I turned old Bentleys into sports cars, I used to have stainless steel trim polished and then black-chromed for a lovely, permanent deep, deep shine without looking like hotrodder bling, and of course total corrosion resistance.

julio

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Re: What is the ideal ratio transmission
« Reply #27 on: March 03, 2018, 11:26:24 AM »
Ok

And if i add this chainguard fixed to my new Surly chainring,  might i need spacers ?

https://www.sjscycles.co.uk/chainsets/thorn-high-quality-alloy-chainguard-for-110-pcd-rings-up-to-38t-black/



« Last Edit: March 03, 2018, 12:06:37 PM by julio »

mickeg

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Re: What is the ideal ratio transmission
« Reply #28 on: March 03, 2018, 12:03:38 PM »
Ok

And if i add this chainguard fixed to my new Surly chainring,  might i need spacers ?

https://www.sjscycles.co.uk/chainsets/thorn-high-quality-alloy-chainguard-for-110-pcd-rings-up-to-38t-black/



Should not need spacers but are the bolts long enough?

Putting a bashguard/chainguard on the outside and the chainring on the inside changes your chainline.  Assuming your chainline was near optimum to start, that difference should not be a problem.  That is the way I run mine and my chainline is off by about 5mm, which I consider to be close enough.

PH

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Re: What is the ideal ratio transmission
« Reply #29 on: March 03, 2018, 01:23:10 PM »
I wouldn't disagree with mickeg, except if there's the possibility of running a perfect chainline, I'd chose to do so. 
I use a similar ring (Similar enough that it's probably the same one without the branding) and to maintain perfect chainline it requires a 10mm longer bottom bracket.  In fact, this is the reason I use it as I ride a bit duck footed and it helps avoid heel strike. Other than that, I'm unconvinced it does much to protect the chainring or my trousers.

Chainline - what it is, why it matters and how to work it out, all you ever wanted to know and probably a bit more:
 https://www.sheldonbrown.com/chainline.html
You might decide not to read any further than this
Quote
The worse the chainline, the worse the mechanical efficiency of the drive train, though research has shown the loss to be minor, at least with modern, flexible chains.


Re chainring choice - Another vote for the Surly. mine lasted and lasted and was only retired when I needed different gearing, it'd done at least 30,000 miles. It's a shame the new size required wasn't available in a Surly, but it's no big deal, on a bike with good chainline they all last really well, so it's not high on my list of priorities. 
« Last Edit: March 03, 2018, 01:24:44 PM by PH »