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Why not cogs outside of drops?

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Why not cogs outside of drops?

Old 05-13-24, 06:49 PM
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Why not cogs outside of drops?

This may be a silly question, but why are no bicycles with cogs outside of the rear dropouts? I know carbon belt drives are a thing, and the frame has to have a break to use them. So why no cogs outside of the rear drop out?
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Old 05-13-24, 07:26 PM
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Like outside the frame? Well, how would the chain run THROUGH the seatstay when you go from outside the dropout to inside?
Maybe a waxed chain might glide through the frame with all it's lubricity but a generic chain won't......

Just get a FD and a 2 speed hub with 12 gears if you want more.
Me? I actively search for lower gear count bikes so I don't have to double or triple shift.
At this rate I will be a sturmey archer guy.
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Old 05-13-24, 07:32 PM
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Why not rims outside of tires while you’re at it?

In all seriousness, I can think of many drawbacks, but what benefits can you imagine from this setup?
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Old 05-13-24, 07:43 PM
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Originally Posted by bboy314
Why not rims outside of tires while you’re at it?

In all seriousness, I can think of many drawbacks, but what benefits can you imagine from this setup?
not having to use a frame that breaks.
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Old 05-13-24, 07:45 PM
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There have been a few over the years, like this English:

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Old 05-13-24, 08:11 PM
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And of course the greatest bike designer of all time, Mike Burrows, was probably the innovator:

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Old 05-13-24, 08:45 PM
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The late Mike Burrows again:

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Old 05-13-24, 10:07 PM
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I hope no designer of "concept bikes" reads this.
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Old 05-14-24, 02:10 AM
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Originally Posted by icedmocha
This may be a silly question, but why are no bicycles with cogs outside of the rear dropouts? I know carbon belt drives are a thing, and the frame has to have a break to use them. So why no cogs outside of the rear drop out?
Because then, instead of the hub rotating around a fixed axle, the axle has to rotate, which makes for a trickier dropout to support a bearing for that, which describes a typical "semi-floating" car or truck axle. Or, a fixed axle that is hollow and the driveshaft fits through it and transmits torque only, does not take bending loads; I just described a "full floating" truck axle. It can be done, just at greater cost.
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Old 05-14-24, 02:10 AM
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Figure out exactly how to secure the wheel to the frame, while at the same time allowing the cogs on the outside of the frame to turn easily, and you're golden.

Sure, it could be done, but there would be a lot of compromises, and it would add complexity. And imagine the Q factor for cranks matched up to an outboard ten speed cassette.
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Old 05-14-24, 07:02 AM
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It should be much easier to make a carbon belt that easily comes apart and back together without compromise.
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Old 05-14-24, 07:18 AM
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I am sure the OP could order a custom frame .... because belt drives represent such a small proportion of the market, making a variety of complex frames for belt-drive bikes doesn't make a lot of business sense.
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Old 05-14-24, 07:33 AM
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Why can't I have a handlebar on the back of my seat?
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Old 05-14-24, 07:38 AM
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Originally Posted by RH Clark
It should be much easier to make a carbon belt that easily comes apart and back together without compromise.
Such belts already exist, but I have no experience of them.

https://www.veercycle.com/products/s...20worry%20free.
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Old 05-14-24, 09:01 AM
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Likely because the cogs outside the dropouts on a conventional bike will require a much wider chain line. And that would mean a much wider q-factor (pedals being further apart). Or there'd have to be additional drive train components to bring the q-factor back to reasonable spacing and then there'll be more loss of energy in the drivetrain that probably wouldn't be desired. Nor would the increased cost to manufacture the bicycle with those extra drive train components.
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Old 05-14-24, 09:18 AM
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Originally Posted by Iride01
Likely because the cogs outside the dropouts on a conventional bike will require a much wider chain line.
I don't see why there would have to be any increase in chain line. Just moving the stays inboard of the cassette would only increase the chain line by the width of the dropouts (so a few millimeters), but the hub could be narrowed to account for that so the chainlink would be the same.
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Old 05-14-24, 09:30 AM
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Originally Posted by asgelle
I don't see why there would have to be any increase in chain line. Just moving the stays inboard of the cassette would only increase the chain line by the width of the dropouts (so a few millimeters), but the hub could be narrowed to account for that so the chainlink would be the same.
I think you'll find that the parts of the hub that retain the free hub will have to be recreated on the outside of the drop and that's going to add more width to the chain line. The narrowing of the stays won't get much narrower than what we had on single speed bikes BITD.

Changing the wheel will take some additional engineering too. And when we get things like this to outside the norm, then manufacturing costs will be high because so few will buy one. Even if it proved to be overwhelmingly superior in several aspects. So manufacturer's willing to make it will change their minds when they don't see a large market share going that way.

I think there have been some bikes with a single stay. However those concept bikes were also too outside the norm for enough people desiring them to make it worth manufacturing them. Perhaps some still are out there in a niche market.
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Old 05-14-24, 09:46 AM
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meh, just put the drive side on the left side....
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Old 05-14-24, 10:22 AM
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I'd prefer that the crank arms be mounted to the handlebar stem with a chain going to the front wheel.
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Old 05-14-24, 11:02 AM
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Originally Posted by prj71
Why can't I have a handlebar on the back of my seat?
Get a tandem!👍🏼
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Old 05-14-24, 01:09 PM
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Originally Posted by Reynolds
I hope no designer of "concept bikes" reads this.
Maybe a Lefty with one chainstay?...
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Old 05-14-24, 01:12 PM
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Originally Posted by Iride01
Likely because the cogs outside the dropouts on a conventional bike will require a much wider chain line. And that would mean a much wider q-factor (pedals being further apart). Or there'd have to be additional drive train components to bring the q-factor back to reasonable spacing and then there'll be more loss of energy in the drivetrain that probably wouldn't be desired. Nor would the increased cost to manufacture the bicycle with those extra drive train components.
And what is the plan for transferring the torque from the cog(s) to the hub body?
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Old 05-14-24, 01:17 PM
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Originally Posted by wheelreason
And what is the plan for transferring the torque from the cog(s) to the hub body?
Beats me, this isn't my idea of a viable option for other reasons. Ask the OP.
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Old 05-14-24, 03:16 PM
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My Gary Fisher Montare (early 90s) had elevated chainstays, so the chain was external to the frame, but not outside the dropout.

Otto
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Old 05-14-24, 06:55 PM
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Originally Posted by Iride01
Beats me, this isn't my idea of a viable option for other reasons. Ask the OP.
Yes, sorry, quoted the wrong post cause I was laughing so hard...
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