Bluechip

I am currently in the process of converting and old Cannondale 3.0 criterium frame to a fixie. I am waiting on an Eno hub from Benscycle. I bought it on Ebay two weeks ago from them but after it had not arrived in about 10 days I contacted them and they said they oversold and are out of stock. I might have it by the end of this week. Maybe. So without the hub I am in limbo. I need to figure out what chainring I want to use. I am using an old 105 set of cranks from my wifes old bike. 165mm arms. It had Bioflex rings so they are useless. I have rings from an Ultegra cranset but they are 53/39's. I don't want to use the 39 because it just doesn't look right to have that small of a front ring. The 53 would be fine along with a 20 tooth cog to give me a 70 inch gear. Question is which side of the crankset inner or outer gives the best chainlne? The 53 won't fit on the inner so if I go that way I have to use the outer. By the looks of it I think the biggest ring that would fit on the inner would be around a 44.

bostontrevor

The 39t ring is probably a bad idea. I like to have more teeth in my 'train. As for which side of the crank, it really depends. If you want to get all scientific and junk, you can look at the specs for the hub and figure out the hub center to sprocket center distance and compare that with the BB center to spider distance. Or you could just wait until you build up your wheel and use a little trial and error to feel it out.

Bluechip

Thanks. I know the easiest solution would be to just wait until I had the hub in hand but I am a little impatient. Anyway I may have found my answer on Sheldon Brown's website.

These hubs feature an eccentric axle mount, finally allowing easy conversion of your existing mountain or road bike to singlespeed or fixed gear without the need for kludgy chain tensioners, even if you've got vertical dropouts!
They are available in 135, 130 and 126 spacings, and feature a 47.5 mm chain line (lines up with the middle ring of a standard MTB crankset, or with the cog flipped over, it will line up with the outer ring of a typical road double.

I also I looked at the Fixed-gear Gallery and it looks like all of the Cannondales that use an Eno hub use the outer cahinring. So I guess I can plan on using the outer position which will allow for larger rings.

roadfix

What I've done in the past was to use the larger ring on the outside and use a shorter BB to get the ring closer to the chainstay to achieve a decent chainline. This may or may not work with your particular frame.

filtersweep

A 39X14 gives you a steeper ratio in the rear than running a 53X20 (if I trust your math). A 20 is pretty large for the rear- I often run an 11-21 cassette on my racing bike.

Frankly, you really can't tell the difference between a 42 and 39 by just looking them.

BTW- it is in especially bad form (actually "illegal") for an ebayer to "sell" you something that is not in stock- definitely worthy of bad feedback. I'd at least negotiate free shipping.

jinx_removing

Agreed. Running the ring "outboard" will look a whole lot nicer, however this may not work for your chainline. Trial and error will work best when you have the wheel you are going to use. BB replacement is almost guaranteed in this situation or you could start messing with axle spacers or both. Measuring everything beforehand will really be the best way to go. Check this out:

https://www.sheldonbrown.com/gloss_ca-m.html#chainline

MKRG

I'm running a 39x13 on the inside of the spider and it's been good for me. RARRRR!
Of course, it's a different frame than yours.

jinx_removing

After further reading it seems that the eno hub should work pretty well with the outer ring according to Sheldon:

"47.5 mm

White Industries ENO hubs use this chainline, which lines up with the middle position of a typical MTB triple. It's also fairly close to the outer position of a typical "road" double."

Of course, this relies on the BB spindle length but it's a start.

Bluechip

The reason I like the larger front rings is purley asthetic. I just like the larger "slice of pie" look. Here are a coulple of examples of the 39 or 42 tooth.

https://www.fixedgeargallery.com/2004/e/barnes.htm

https://www.fixedgeargallery.com/2004/e/ferdinando.htm

Here is one with a 52.

https://www.fixedgeargallery.com/tetro.htm

I might go with the 53/19 which is a 73.7 inch gear. I'll test that combo out on my road bike tonight.


"BTW- it is in especially bad form (actually "illegal") for an ebayer to "sell" you something that is not in stock- definitely worthy of bad feedback. I'd at least negotiate free shipping"

Yeah. I was not too happy about that. I was even less happy when the day after I paid they listed a complete wheelset w/eno hub for only about $50 more than I paid for the hub alone. It was snapped up before I noticed it.

Bluechip

Whle looking further at Sheldon Brown's website I noticed that he is using a Biopace ring on one of his Eno hubbed fixies. I thought that would have been a definate no-no. The chain tension has to be very inconsistent.
https://sheldonbrown.org/rambouillet/index.html

ryan_c

With a larger front ring you have to cuff your pants more...

edit: Inside of the spider usually works with track cogs, I believe. Usually a 41mm chainline. That ENO sounds way out there! (like you said, obviously, outside of spider). I had more to say but it already got said above. I need to read better before I post.

HoboRandy

People are often astonished to learn that I ride Biopace chainrings on fixed-gear bikes. They imagine that there will be tremendous changes in chain tension as the chainring rotates. In practice, this is not the case. A 42 tooth chainring will generally engage 21 teeth against 21 chain rollers, regardless of its shape.

There is a sligth variation in tension resulting from the varying angle between the two straight runs of chain as the axis of the chainring rotates, but this has not generally been of a sufficient magnitude to cause any problem in practice for me.

Quoted from this page: https://sheldonbrown.com/biopace.html

I would have agreed with you, Bluechip, but I guess it works out for Sheldon.

BostonFixed

re: Biopace

Actually, no. Biopace was designed that two opposing sides of the ring would always be in contact with the chain, thus giving equal chain tension. The more oblong side of the ring would me in contact with the less oblong side of the chainring, thus creating equal tension at all times.
Biopace was (is?) a good idea for low rpm grunting, such a hill climbs on a SS MTB, But not so good for fast RPM spining.(>90 RPM)

HoboRandy

I have no experience myself, but Sheldon Brown does dismiss the cadence issue at the link I posted.

mwangarch

I went cheap with my 3.0 and just added a tensioner, new chain and 16T freewheel with a couple of spacers to get the chainline reasonably close.

Cynikal 

You will have better chain contact if you run the tensioner "pushing up". Plus it looks cleaner.

Bluechip

Here is a pic of how it looks right now. Just waiting on the Eno hub to build up the wheel and a few small bits from Loose Screws.

glomarduck

Nice I have one of those (10 speed no wheels and funky) sitting in my room right now. Not really a race bike more of a "health food bike". Nice job.

ImprezaDrvr

I have tried running my 44 on the inside and outside of the cranks with little noticeable difference. It was a bit noisier on the outside than the inside, but that could well have been my imagination. It indeed sucks to wait on parts; I've had a rim on order for two weeks now with my LBS. First time they've ever let me down and I'm sure that the discount will reflect the slow delivery. At any rate, I have a CAAD3 frameset that I converted to fixie with the ENO, just to show some relevance. I just put my D/A cranks back on the bike after running old RX100's for a while, so the chainring might end up on the outside. As for the appearance, it really doesn't make much difference, believe it or not, at least not to me. But then my fixie's more about form following function.

Bluechip

The hub got here this afternoon and I've already laced the wheel. It took me about an hour. Not to bad considering it's been about 15 years since I've built a wheel. I just used another wheel for reference and I even got the correct gap at the valve hole. I'll see if I have time to true it up tonight but I still don't have a cog or lockring. They are supposed to be here Tuesday. Maybe I might have to go and get another set locally and then I'll have differant gearing options. Like I said I am a little impatient.

smurfy

Great thread - I've been thinking of converting my C-dale R300 2.8 frame to fixed or SS, but I'm not sure which.