Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Feel of pairing more-ovalized 28t with less-ovalized larger biopace chainrings

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Feel of pairing more-ovalized 28t with less-ovalized larger biopace chainrings

Old 10-02-18, 11:28 AM
  #1  
TallRider
Senior Member
Thread Starter
 
TallRider's Avatar
 
Join Date: Oct 2005
Location: Fresno, CA
Posts: 4,432
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Feel of pairing more-ovalized 28t with less-ovalized larger biopace chainrings

I'm a fan of biopace chainrings. Not looking to debate their merits here.
Shimano produced biopace chainrings with different degrees of ovalization. My understanding is that the more-ovalized rings were usually for mountain bikes, and sometimes the smaller rings were more ovalized than the larger.

Based on parts I have sitting around, I'm thinking of pairing a more-ovalized 28t biopace granny gear with less-ovalized 42-52 biopace chainrings produced for road bikes.

I'm wondering how awkwardly different pedaling is likely to feel when shifting from 42t into the 28t granny. Biopace rings feel somewhat different while pedaling.

I can see two reasons to not worry about this:
1) some people run a biopace granny chainring with round larger, to get the benefits on long climbs at lower RPMs.
2) I'm setting up the gearing with a wide range cassette, so the 26t granny gear would only be used as for long climbs - that is, I wouldn't be frequently shifting between 42 and 28, so would have few times getting used to the different pedal-stroke feel of biopace.

But if people have matched biopace granny gears with round larger chainrings, or more-ovalized biopace granny with less-ovalized biopace larger rings, and found this substantially annoying, then I'll avoid it.

I could always just buy a Biopace SG chainring (the less-ovalized version) 26t or 28t on eBay.

EDIT: the 28t granny gear that I have is more ovalized than the SG versions I've seen, but its profile doesn't look *that* different from the less-ovalized 42 road ring (52 is the same profile) that it'll be paired with. I'm going to try it anyway, but am less worried after this direct visual comparison.


Last edited by TallRider; 10-02-18 at 04:21 PM. Reason: uploaded photo
TallRider is offline  
Old 10-02-18, 11:57 AM
  #2  
dsbrantjr
Senior Member
 
dsbrantjr's Avatar
 
Join Date: Sep 2010
Location: Roswell, GA
Posts: 6,227

Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 654 Post(s)
Likes: 0
Liked 47 Times in 43 Posts
Since you have the parts in hand you have little to lose but some time to find out. I suspect it will be a non-issue. I had Biopace and non-Biopace bikes and never noticed any difference.
dsbrantjr is offline  
Old 10-02-18, 12:17 PM
  #3  
bnewberry
Senior Member
 
Join Date: Oct 2017
Posts: 182
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 59 Post(s)
Liked 0 Times in 0 Posts
Your feet go around in a circle because the cranks don't change length as you pedal! You won't notice the difference in the degree of oval at all.
bnewberry is offline  
Old 10-02-18, 01:14 PM
  #4  
3alarmer
******
 
3alarmer's Avatar
 
Join Date: Nov 2010
Location: The Big Tomato
Posts: 17,280

Bikes: old ones

Mentioned: 226 Post(s)
Tagged: 0 Thread(s)
Quoted: 14545 Post(s)
Liked 74 Times in 63 Posts
...I have some practical experience with this. It was (at least at one time) a common hack for touring bikes that would be heavily loaded and aimed uphill to install a Biopace granny ring.

I have two bicycles set up this way (with regular round Shimano rings in the two larger positions). There is a distinct neutral position on every crank stroke that feels almost like the freewheel is slipping until you get used to it. It does make for easier uphill grinds with a heavy load (at least it does for me). I have heard from others they don't like the feeling, so as in all things, YMMV.
3alarmer is offline  
Old 10-02-18, 01:26 PM
  #5  
Crankycrank
Senior Member
 
Join Date: Jan 2009
Location: San Diego, CA
Posts: 1,340
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 184 Post(s)
Likes: 0
Liked 11 Times in 8 Posts
This seems like a question that nobody can answer for you. Everyone would probably have a different experience as far as liking it or not. Chainrings are pretty simple to switch out. Just try it and judge for yourself.
Crankycrank is offline  
Old 10-02-18, 01:28 PM
  #6  
prathmann
Senior Member
 
Join Date: Nov 2008
Location: Bay Area, Calif.
Posts: 7,260
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 657 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Never had any issues with switching back and forth between bikes with Biopace vs. round chainrings, so I wouldn't expect any issues with your arrangement.
prathmann is offline  
Old 10-02-18, 02:29 PM
  #7  
TallRider
Senior Member
Thread Starter
 
TallRider's Avatar
 
Join Date: Oct 2005
Location: Fresno, CA
Posts: 4,432
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by 3alarmer View Post
...I have some practical experience with this. It was (at least at one time) a common hack for touring bikes that would be heavily loaded and aimed uphill to install a Biopace granny ring.

I have two bicycles set up this way (with regular round Shimano rings in the two larger positions). There is a distinct neutral position on every crank stroke that feels almost like the freewheel is slipping until you get used to it. It does make for easier uphill grinds with a heavy load (at least it does for me). I have heard from others they don't like the feeling, so as in all things, YMMV.
Thanks for the response. This is what I'm looking to get info on. I have biopace rings on two different bikes, and am comfortable with the feeling.
The main thing I'm curious about is how different it feels to shift between biopace and non-biopace (or in my case, very biopace and less-biopace) on the same bike. How much of a feeling of adjustment is/was there for you, when shifting back and forth between biopace and round while riding?
TallRider is offline  
Old 10-02-18, 03:40 PM
  #8  
3alarmer
******
 
3alarmer's Avatar
 
Join Date: Nov 2010
Location: The Big Tomato
Posts: 17,280

Bikes: old ones

Mentioned: 226 Post(s)
Tagged: 0 Thread(s)
Quoted: 14545 Post(s)
Liked 74 Times in 63 Posts
Originally Posted by TallRider View Post
Thanks for the response. This is what I'm looking to get info on. I have biopace rings on two different bikes, and am comfortable with the feeling.
The main thing I'm curious about is how different it feels to shift between biopace and non-biopace (or in my case, very biopace and less-biopace) on the same bike. How much of a feeling of adjustment is/was there for you, when shifting back and forth between biopace and round while riding?
...took about ten minutes to adjust to the feeling of having a neutral (no load) moment in each pedal stroke.
Once you assure yourself that nothing in your gear train is slipping or disconnected, it makes pedaling up a steep gradient with a load easier.
3alarmer is offline  
Old 10-02-18, 04:19 PM
  #9  
TallRider
Senior Member
Thread Starter
 
TallRider's Avatar
 
Join Date: Oct 2005
Location: Fresno, CA
Posts: 4,432
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by 3alarmer View Post
...took about ten minutes to adjust to the feeling of having a neutral (no load) moment in each pedal stroke.
Once you assure yourself that nothing in your gear train is slipping or disconnected, it makes pedaling up a steep gradient with a load easier.
I'm not sure if you're talking about the general feeling of riding a biopace crank for the first time, vs the feeling of shifting from the round ring to the biopace granny gear on a given bike.
I have biopace rings on two different bikes, so I'm fine with the feeling.

My question is specifically, when riding a bike with a biopace granny and round larger chainrings, how weird does it feel to shift back and forth between the biopace and the round rings? If it's a 10-minute adjustment each time I shift between chainrings, that would be pretty bad. I imagine the 10 minutes you refer to is just the first time riding a bike with biopace chainrings, though. Can you clarify? Thanks.

Last edited by TallRider; 10-02-18 at 04:22 PM.
TallRider is offline  
Old 10-02-18, 04:53 PM
  #10  
3alarmer
******
 
3alarmer's Avatar
 
Join Date: Nov 2010
Location: The Big Tomato
Posts: 17,280

Bikes: old ones

Mentioned: 226 Post(s)
Tagged: 0 Thread(s)
Quoted: 14545 Post(s)
Liked 74 Times in 63 Posts
...just the first time. The feeling of a neutral, unloaded spot is more pronounced on the smaller Biopace rings I use. Once you expect it, it's not a problem.
3alarmer is offline  
Old 10-02-18, 05:08 PM
  #11  
TallRider
Senior Member
Thread Starter
 
TallRider's Avatar
 
Join Date: Oct 2005
Location: Fresno, CA
Posts: 4,432
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by 3alarmer View Post
...just the first time. The feeling of a neutral, unloaded spot is more pronounced on the smaller Biopace rings I use. Once you expect it, it's not a problem.
Thanks! I'll try it out.
TallRider is offline  
Old 10-02-18, 08:19 PM
  #12  
tcarl
tcarl
 
Join Date: Dec 2010
Location: St. Louis, MO
Posts: 536

Bikes: Roark, Waterford 1100, 1987 Schwinn Paramount, Nishiki Professional, Bottecchia, 2 Scattantes, 3 Cannondale touring bikes, mtn. bike, cyclocross, hybrid, 1940's era Schwinn

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
If your question is specifically "how weird does it feel to shift back and forth between the biopace and the round rings", I wouldn't worry about it. First of all, a 42 to a 28 is a pretty big jump. You're going to feel the (weird) difference in cadence and resistance (or pedaling ease) between the two size chainrings more than the difference between round and "not round". Second, you're probably only going to switch to the 28 at or just before a major hill (i.e. lots of pedaling effort and pressure). You'll probably be more concerned about climbing the hill than about how "different" the biopace feels. Plus, as you already know, the biopace will feel nicer on that hill than a round ring. How long will it take to adjust to the biopace granny from a round ring? Pick an answer: 1 - you won't care. 2 - pretty or real quickly. 3 - within a few minutes at most. 4 - by the time you're really into the big hill you won't be thinking about it. I base all these comments on my still having bikes with both round and biopace chainrings; having used both the "less biopace" 42/52 road biopace and the "more biopace" 28/38/48 mountain/touring bike set; and having in the past a touring bike with a mixture of round and biopace chainrings. Actually, based on my experience I kinda get the sense you're overthinking it. It's not that there isn't a difference (in feel) between them, you just use them - ride them, and your legs and feet adjust. Really, the 42 - 28 gearing drop will probably be "weirder" than the round to biopace.
tcarl is offline  
Old 10-03-18, 02:03 AM
  #13  
TallRider
Senior Member
Thread Starter
 
TallRider's Avatar
 
Join Date: Oct 2005
Location: Fresno, CA
Posts: 4,432
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by tcarl View Post
If your question is specifically "how weird does it feel to shift back and forth between the biopace and the round rings", I wouldn't worry about it. First of all, a 42 to a 28 is a pretty big jump. You're going to feel the (weird) difference in cadence and resistance (or pedaling ease) between the two size chainrings more than the difference between round and "not round". Second, you're probably only going to switch to the 28 at or just before a major hill (i.e. lots of pedaling effort and pressure). You'll probably be more concerned about climbing the hill than about how "different" the biopace feels. Plus, as you already know, the biopace will feel nicer on that hill than a round ring. How long will it take to adjust to the biopace granny from a round ring? Pick an answer: 1 - you won't care. 2 - pretty or real quickly. 3 - within a few minutes at most. 4 - by the time you're really into the big hill you won't be thinking about it. I base all these comments on my still having bikes with both round and biopace chainrings; having used both the "less biopace" 42/52 road biopace and the "more biopace" 28/38/48 mountain/touring bike set; and having in the past a touring bike with a mixture of round and biopace chainrings. Actually, based on my experience I kinda get the sense you're overthinking it. It's not that there isn't a difference (in feel) between them, you just use them - ride them, and your legs and feet adjust. Really, the 42 - 28 gearing drop will probably be "weirder" than the round to biopace.
Thanks. Glad to have drawn out another person who has experience along these lines.
And yeah, since I expect to only use the 28 on significant climbs, it probably won't bother me much to have the pedal stroke become a bit more biopace-y.
I didn't feel like bringing up another strange thing in my original post, since I had a specific question, but this bike will actually be a sub-compact double. I'm running a 42/28 with an 11-32 cassette. The 42-11 is the same big gear as a 46-12, and I'll stay in the 42 ring for most riding, just shifting over the wide-range cassette. And for longer and/or particularly steep climbs, I'll shift into the 28 front ring. My introduction to this approach originally came from Jan Heine at Bicycle Quarterly, who rides a 46/30 crankset, mounted a bit inboards from a typical double since most of the time is spent in the big ring and the small is just for climbs. Here's a recent post where he reiterates the reasons for this setup.
And here's a pic of the crankset now that I put it together. Using a triple but with a chainguard mounted in the outer ring's place.
TallRider is offline  
Old 10-03-18, 04:34 AM
  #14  
dsaul
Senior Member
 
Join Date: Jan 2013
Posts: 1,043
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 235 Post(s)
Liked 28 Times in 22 Posts
I currently have an oval(modern version/not biopace) 34t and a round 48t chainring on my gravel bike. In shifting down from the round ring to the oval, I don't notice any difference other than the fact that it is easier to maintain my cadence when climbing. When I shift from the small oval chainring to the larger round chainring, i notice that the pedal stroke feels "lumpy". It feels harder to get the pedals back over the top on each side. This feeling only lasts for a short time and then it feels normal again. I would prefer to have an oval large chainring, but I can't find one smaller than a 50t to fit my 5 bolt 110bcd crankset.
dsaul is offline  
Old 10-03-18, 09:18 AM
  #15  
tcarl
tcarl
 
Join Date: Dec 2010
Location: St. Louis, MO
Posts: 536

Bikes: Roark, Waterford 1100, 1987 Schwinn Paramount, Nishiki Professional, Bottecchia, 2 Scattantes, 3 Cannondale touring bikes, mtn. bike, cyclocross, hybrid, 1940's era Schwinn

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by TallRider View Post
Thanks. Glad to have drawn out another person who has experience along these lines.
And yeah, since I expect to only use the 28 on significant climbs, it probably won't bother me much to have the pedal stroke become a bit more biopace-y.
I didn't feel like bringing up another strange thing in my original post, since I had a specific question, but this bike will actually be a sub-compact double. I'm running a 42/28 with an 11-32 cassette. The 42-11 is the same big gear as a 46-12, and I'll stay in the 42 ring for most riding, just shifting over the wide-range cassette. And for longer and/or particularly steep climbs, I'll shift into the 28 front ring. My introduction to this approach originally came from Jan Heine at Bicycle Quarterly, who rides a 46/30 crankset, mounted a bit inboards from a typical double since most of the time is spent in the big ring and the small is just for climbs. Here's a recent post where he reiterates the reasons for this setup.
And here's a pic of the crankset now that I put it together. Using a triple but with a chainguard mounted in the outer ring's place.
I think that sounds like a pretty good set-up, I like your logic, and I think it'll work well for you.
tcarl is offline  
Old 10-03-18, 10:41 AM
  #16  
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 29,292

Bikes: Catrike 559 I own some others but they don't get ridden very much.

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1162 Post(s)
Liked 32 Times in 24 Posts
Originally Posted by dsbrantjr View Post
Since you have the parts in hand you have little to lose but some time to find out. I suspect it will be a non-issue. I had Biopace and non-Biopace bikes and never noticed any difference.
That's what I think too. If you try it and you like it, does it matter what anybody else thinks? Another thing to experiment with is the orientation of the oval axis. Some riders report liking different orientations. I've got a 28t biopace on my recumbent trike (with circular bigger rings). I set the oval axis one hole off because I'm pedaling horizontally rather than vertically. I don't really have a subjective opinion because I use it so seldom.
__________________
My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
Retro Grouch is offline  
Old 10-03-18, 12:08 PM
  #17  
TallRider
Senior Member
Thread Starter
 
TallRider's Avatar
 
Join Date: Oct 2005
Location: Fresno, CA
Posts: 4,432
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by tcarl View Post
I think that sounds like a pretty good set-up, I like your logic, and I think it'll work well for you.
I can't claim responsibility for the logic, it's something I got from Jan Heine of Bicycle Quarterly. Heine is a very strong rider with a racing background, but now he rides long distances over varied terrain, which has different demands than racing. A 46-12 high gear (or 42-11 in my case) is plenty for everything except group rides or races where you need to be able to hang on to a paceline on a slight downhill or with a tailwind.

While the 50/34 "compact" crankset has thankfully become more common on road bikes than the pure racing gearing of a 53/39 double crank, the 50/34 is still bigger than riders need for general riding. Having a slightly bigger gear barely matters for average speed, because when you're descending really fast you are probably tucking without pedaling anyway. But having a lower gear for more comfortable climbing (in my case a 28-32, below 1:1 ratio) is totally worth it.

A double crank is also more convenient than a triple, for both shifting and chainline considerations.
TallRider is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
sloar
Classic and Vintage Sales
2
07-29-17 04:27 AM
Johnny 831
Bicycle Mechanics
22
02-10-15 04:10 AM
Joe New
General Cycling Discussion
2
01-16-14 04:19 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.