Vixar

Somebody told me that is impossible to maintain the proper chain tension in this case and a chain tensioner is mandatory. However, there are plenty of videos on YT with conversions using a chain link (92 links - too loose, 90 links
- too tight, impossible to mount the chain, 91 links - just perfect). What do you think ? What are the pros and cons of using this method vs chain tensioner ? Thanks ! …And happy new year !!!

wolfchild

It's only a temporary solution which doesn't last very long...Your chain will stretch after a couple of rides and it will be impossible to maintain proper tension...The proper way to do it is to use a chain tensioner or just buy a frame with drop outs designed for SS use.

Vixar

Anyone else ? Maybe somebody who has a SS bike with the chain link solution.

veganbikes

If a single speed use a chain tensioner. Chains really don't quite stretch so much as material wears out from the bushings and pins It is more a chain deformation or maybe elongation as the actual links don't change in size. Really though get a bike designed to be a single speed or fixed gear it will be way more fun and way more practical. Really my only reason to do a vertical drop out single speed is if I was desperate to get home and my derailleur was completely busted and unusable.

You can play around with magical ratios and sometimes get lucky but it just isn't worthwhile with so many different single speed and fixed gear bicycles out there plus a whole host of awesome dropouts that allow for both in so many different kinds of bicycles. Plus you have some really awesome chain tensioners out there from high end to bottom end and also if you set up a derailleur right it can also be a single speed tensioner.

wolfchild

Yes bushngs and pins wear out....but the term " chain stretch " is a very common term used to describe chain wear. Even bike shops and bike mechanics use that term. Many a time I have compared a worn out chain to a brand new one and there was a very noticeable difference in the overall length. IMHO magic gear ratios isn't a proper way to go about it when dong a SS conversion.

Sorcerer

Hello, in regard to SS and vertical dropouts the employ of a ghost ring comes to mind.

This is a technique I haven't personally tried - but I have seen it used successfully.

It entails the insertion of a chain-wheel (chainring) inside the chain loop next to the chainstay. The chain-wheel remains stationary and it's size tensions the chain.

Sorry I do not have a photo

Not having tried this I have a few misgivings about the concept. I hope some here can reply from experience.

One is that on most frames wouldn't the ghost ring rub in the chain-stay?

Two, can the ghost ring become dislodged and cause chain drop?

As the chain stretches how often does the ghost ring need to be swapped out for a bigger ghost ring?

veganbikes

Common but incorrect term. The links again don't stretch it is material wearing out and deforming which is changing the pitch of the chain but the links are still the same length the stuff inside is just deforming which will cause elongation (not of the links) and slop and then problems shifting or not in this case.

frankenmike 

Rear wheel built with an Eno hub is probably the best way. Very expensive however.

grant40

Here is one that I made very successfully. I never had any problems with it at all. The only thing is that you are forced to use a certain gear ratio whether you like it or not.

79pmooney

This isn't much more that playground talk. Everyone knows what you are talking about when you say"stretch". And in fact, it matters near zero whether it is actually stretch or is in reality wear. (Yes, it matters big time to the chain manufacturers, the OCD and the crowd here, but not on the road.)

To the OP's issue - 1) 1/2 links (female on one end and male on the other) work very well. I've only seen them in 1/2" by 1/8", the old single speed standard (and common in industry.) Easy to find and cheap. Some bike shops, especially those that cater to the fix gear crowd and any good hardware store. (Ace Hardware for one.) The bike shop ones use a screw that threads into the plate. I'd Locktite that. The hardware store ones use cotter pins with clevis pins. The clevis pins may cause clearance issues but are very secure. Mariners have been sailing the world's oceans with them the past century. I have many thousands of miles on half links. I replace them with the chain and remove them if needed with the surrounding links. (Driving and re-driving pins on 1/8" chains with real protrusion of the links past the plates can be done many times safely. One of those chains is the $25 Isuzu.)

I've heard nothing but good about using ghost rings. Granted, not many do it. Odd is not something we cyclists gravitate to. And I'd guess that it would be easy to move the ring back periodically to adjust for chain "stretch").

Another approach - use a hub with (or retro fitted to) a quick release. Cut the axle down to just short of the dropout. Now you have the skinny QR skewer in the much wider dropout slot and the adjustment ability to set proper chain slack. There's a thread going around now on this topic. Shouldn't be hard to find. Sheldon Brown also discusses it (and is how most learn of the concept).

Or, do what many of us do - go out and find an early 1980s bike. Horizontal dropouts were the rule for all but the highest end models then. Many old Japanese bikes (and the US and European near copies) make excellent single speed and fix gear rides. (Plus they are road bikes with good handling on roads, not velodromes and have the convenience of forward facing dropouts rather than backwards facing track ends; a blessing every time you take the wheel off.)

Ben - the guy who's been riding fix gears forever.

Vixar

What gear ratio ?

Eric F

That hasn't been my experience. I got really lucky on this bike that a 32 x 19 ratio works well for my terrain AND it's a magic ratio where the chain length works out to a full link, and a tensioner is not needed. It was a little too tight when the chain was new, but in a few rides, a little chain stretch and a little cog wear has resulted in perfect tension. I have over 300 miles on the same parts, and everything is still running great. At some point, I will need to replace the chain, and start the process over again, but I don't foresee that any time soon, especially since this bike is not get a ton of regular use.

wolfchild

Run it for 2000 miles and then let's see how the chain tension is and how the magic gear ratio works out.

79pmooney

That looks like a 52 x 17. If so, 3.06:1 or 83 gear inches. (The fact that you cannot shift doesn't change the fact that it is a gear train with a ratio.)

TomPalmer

Sweet Trek!

Tom

TugaDude

For those who haven't seen one, here's a pic I found on the interwebs of a ghost ring. It just goes along for the ride.

TugaDude

There are a lot of weird things that actually can work. For example, Biopace rings on fixed gear. I owned an IRC frame for awhile and when I bought it used it had a biopace ring installed and it ran perfectly. Although the ring is oval it maintained tension throughout the revolution.

The subject of "perfect" chain tension always comes up. I guess there may be such a thing, but that doesn't mean there cannot also be a degree of subjectivity. I read posts about perfectly round chainrings and such and it seems to me the pursuit of perfection can become a bit obsessive.

Eccentric hubs, eccentric bottom brackets, "magic gears", half-links, ghost rings, tensioners, all can work adequately.

But as Veganbikes said, just get yourself a frame built for the intended use and get on with it.

Eric F

No problem. My bike was built with the expectation of replacing the chain if things got too loose - it's $25 and a few minutes of work. Your previous post said that it would be impossible to maintain tension after a few rides. I have a few dozen rides on my bike, and after the initial settling in, there hasn't been a significant change in chain tension. If it goes 2000 miles before needing a change, that's great. At the rate my SS gets ridden, that'll be a few years away. I'm okay with changing a chain every few years.

I don't understand how a "magic" gear ratio would change. Maybe parts need to be refreshed if they're too worn, but that's just a maintenance issue. It doesn't change the fact that 32x19 on my bike works great without needing an additional tensioner.

TugaDude

Just relax and ride!

79pmooney

"Perfect chain tension". I prefer to say "slack" as there should never be tension when your feet are off the pedals. There's a range of acceptable. And if you use less than velodrome quality cranksets, BBs, hubs and cogs, it is quite unlikely that everything adds up to being round and uniform so as you pedal the chain goes tighter, then slacker.

I have two bikes set up with 110 BCD road cranksets. 1/8" fix gear chainrings. On both, there is real tension change. I have to pay attention to setting chain slack so it doesn't go fully tight or loose enough to throw off spinning fast downhill. Now, the bike of my avatar photo has the excellent Sugino 75 crankset. Adjusting the slack on that bike is a joy. I like to get it right on/perfect but I can miss by a mile and still never go too tight or loose. So @Vixar, one thing you can do is optimize your crankset to be as perfect as possible and make all the chain adjustment issues at the hub simpler. (Sheldon Brown has a piece on optimizing the roundness of chainrings on less than perfect cranksets. In his section on fix gears.)

Vixar

Thanks everybody for your input. I’m perfectly happy function-wise with the chain tensioner of my Focus Arriba pictured above, but I wanted to know if it’s a simple and cheap and reliable way to obtain that clean look and simplicity of a chainring-chain-cog system. I guess I’ll stick to current configuration, it’s not worth the hassle.

veganbikes

That looks like a fine set up I wouldn't change it at all.