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Stock gearing on a Co-Motion Speedster too high?

Old 03-14-18, 06:14 PM
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Stock gearing on a Co-Motion Speedster too high?

We have recently gotten a brand new Co-Motion Speedster, and are finding the gearing too high (hard). Moderate hills (5-7% grade) have us in the bottom gear and wishing we had another...and this is unloaded, on short hills.

On our last bike, a 15-year-old used model, we swapped out the rear cassette to get a couple of additional gears for climbing and used them frequently while touring with full panniers on rolling hills. We didn't mind the hassle/expense because it was an older bike and not designed for the way we were using it.

However, we're a little disappointed to be considering switching out a brand-new cassette on a bike that is billed as a touring bike. We're small and fit, so we wouldn't expect to need more gears than the average buyer. Before we make the switch, I wanted to see if 1) this is a common experience and 2) if there's something we might be missing.

Thoughts appreciated!
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Old 03-14-18, 07:19 PM
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What exactly is the lowest gear on your new bike? The Comotion website lists the Speedster with 34/40 lowest gear , is this what you have? That seems reasonable for many teams and conditions. Our tandems with triples have low gears of 30/34 (actually higher than 34/40), and I have lowered our Speedster with a triple to 26/34. At that ratio we are climbing steep hills at less than 4 mph.
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Old 03-14-18, 07:19 PM
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The Speedster is listed as having 50/34 chainrings and 11-40 cassette. Is that whatís on your bike?

We currently have tandems setup with 52/34 x 11-42 and 52/42/28 x 11-34. Iíd say that we would want wider range than the stock offering, too.
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Old 03-14-18, 07:36 PM
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A 34/40 combo is 23 gear-inches. The lowest gear on our triple is 26/34, which is 21 gear inches, so a little lower than the stock Co-Mo but not much. We tour loaded comfortably with our gearing. Could be higher if we stayed out of the mountains.
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Old 03-14-18, 07:39 PM
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If your not happy call Co-Mo up to see if they will work with you, maybe cost on components, gearing is clearly listed on there web site. You should have addressed your concerns before hand on the gearing that was provided. You will need a Wolf Tooth Road Link to accommodate larger gearing on the rear cassette, plus a few more links on existing chain, or a new chain.
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Old 03-14-18, 08:08 PM
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If it were a triple, would be relatively easy to just swap out for a smaller inner ring. But it's not.
If moderate hills - unloaded - have you wishing for a lower gear, sounds like something needs to change.
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Old 03-14-18, 10:17 PM
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Then change it.. the parts choice is yours. now..

"Speedster " suggests going fast so they geared for speed.
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Old 03-15-18, 06:37 AM
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The interesting thing here to me is that CoMotion has gone to 2x setups for all of their higher end, non touring tandems.

While this may be where the market is going, it doesn't appear to be the best answer for all teams.

That said, 34/40 is a pretty low gear. If you're struggling up short 5-7% grades, unloaded in that gear, you're using a different definition of "fit".
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Old 03-15-18, 06:54 AM
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Originally Posted by fietsbob
Then change it.. the parts choice is yours. now..

"Speedster " suggests going fast so they geared for speed.
Actually I don't think they did. They spec'd a 2x system with the belief that this is what their customers want, and which is now more viable with wider range 11-40 cassettes.

IMHO, however, the problem with Co-Mo's current specs is that they do not work as well for fast riding.

The 50x11 top end is low for a tandem. (It would definitely be a limiter doing a TT, particularly with downhill or downwind segments).

More importantly, the 11-40 cassette leaves big gear jumps which are more noticeable when you are riding fast.

The 3x10 setup on our older Co-Mo Robusta, in my opinion is a better setup for fast riding. With chain rings of 53/39/26, and an 11-28 cassette, it has a higher top end, as low a low end, and better spacing, than the way they now spec their bikes with a 2x setup including the Speedster.
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Old 03-15-18, 07:10 AM
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If you have a triple crank set it is an easy fix by swapping out the 30 tooth small chain ring to a 28 but if it is as now showing on the website a double chain set it will be a little more challenging. I was surprised to see that they have gone to double chain rings on so many of the bikes now. Especially as they switched-out the Speedster from a sport bike to a touring bike when they went to the open frame design a few years age. A call to your shop or Co-Motion might be in order. You should find out what the maximum large cog your rear derailleur will handle to see if it can handle a 42. If not the Wolf Tooth Road Link, which was mentioned above, is a good option to get lower gearing by expanding to capability of your rear derailuer. Check out those options before a major overhaul to convert to a triple chain rings crank and new shifter and derailleur. Good luck and I'm so sorry you are experiencing this.
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Old 03-15-18, 08:44 AM
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Thanks for the thoughts, everyone! We talked to the dealer last night, and we figured out the issue: According to his records, our rear cassette is 11/32. I think 11/40 would give us plenty of range. (The dealer also said what our front triple ring is and now I forget...)

The dealer offered to swap out either the rear cassette or the small chainring for the cost of the part, no labor. But now that I see that 11/40 is listed as stock on the web site, and we didn't discuss making any changes, I'm wondering if we should have to pay for the part. The bike has less than 100 miles on it, so it really is a brand new cassette. In any case, it's a full day's drive for us to go get it swapped out.

I'd appreciate any thoughts or suggestions on what's fair to expect. Thank you again!

Last edited by Kiramarch; 03-15-18 at 08:52 AM.
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Old 03-15-18, 08:53 AM
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~2016 and earlier Speedsters had 52/39/30 x 11-32 gearing, which is pretty reasonable. It's worth looking at your bike and counting teeth on the smallest chainring and largest rear cog.
Was your bike a floor model that theoretically has all stock components?
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Old 03-15-18, 10:09 AM
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It's a 2017 that was built up just for us, and we asked for the stock components for everything except my handlebars, so I would have expected it to match what was billed on the web site. But if the 11/32 was standard until recently...hmm.
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Old 03-15-18, 10:25 AM
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Rohloff 36 hole hubs work well on tandems , both cranks can be right side drive.. now they have an electronic shifting option .
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Old 03-15-18, 10:50 AM
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In any case, it's a full day's drive for us to go get it swapped out.
A new cassette online is $50+- plus a new chain $35+- (for longer length) will probably be less cost than a days drive with gas and wear/tear on your car. Any decent LBS can swap out a chain and cassette.

I would change it out myself or go to a local shop instead of driving a day to pay him for replacement parts.
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Old 03-15-18, 11:54 AM
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I’m still unclear: does your bike have 2 chainrings or 3? How many teeth on the chain rings? If the bike is leftover from last year and has a triple, the easiest solution is to swap the smallest chain ring for one with fewer teeth.
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Old 03-15-18, 12:08 PM
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As this topic of double vs triple has been discussed many times on this forum, your bike is in sort of no mans land with a common cassette for a triple but no so great for a double. A 11-40 and 50/34 has become a very common setup for tandems. It will give you a very wide range and will shift very well. You need to check which length cage was installed on the rear derailleur as using a 40 on the rear usually requires a road link or K-edge for optimum shifting. We have used this combo for a number years and climbed many passes with it including all the major passes in Colorado and many climbs in Europe. We recently used this also on a loaded self supported tour last fall. Change it out and enjoy your new tandem. If you ever decide to race you can always go to mid compact on the front with 52/36 chainrings to get a higher top end.
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Old 03-15-18, 12:20 PM
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If you're going to have something custom built, it's a good idea to specify the components so that you get what you want.

We still don't know exactly what you have, so it's hard to give sensible advice. Up front, you must have a 10-speed crankset either with 53-39-30 or 50-39-30 rings. Except for the 30, those rings are not interchangeable, but what you want is the former, not the latter, which might mean a stoker BB change, too. Although the 50T big ring might be fine for you.

In the back, if you indeed have a 10-speed system, you have the choice of 11-32, 11-34, or 11-36. The 40T cassette is only offered in 11-speed. If you have a triple up front, it's very unlikely that you have an 11-speed system.

My advice is to create a spread sheet with gearing tables. Y axis - chainring teeth. X axis - cassette teeth. You can find the teeth for various cassettes here:
2018-2019 SHIMANO Product Information Web

Each cell should contain the formula: (chainring teeth)/(cassette teeth) * 27. This formula expresses gearing ratios as Gear-Inches (GI). GI * Pi = approximate forward travel of bike for each pedal revolution.

Have a table showing the gearing of your old tandem, which apparently you liked.
Then have a table(s) showing gearing options for your new bike. This is a very easy way to get the gearing you want without trial and error.

In the new tandem tables, look at the difference between a 30T and 26T inner ring combined with the various available cassettes. We prefer a 26T with an 11-34 cassette to get closer low ratios.
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Old 03-15-18, 12:27 PM
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This is what a gearing table for a 10-speed might look like:
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gearing table.jpg (17.4 KB, 237 views)
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Old 03-15-18, 02:18 PM
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Originally Posted by Kiramarch
Thanks for the thoughts, everyone! We talked to the dealer last night, and we figured out the issue: According to his records, our rear cassette is 11/32. I think 11/40 would give us plenty of range. (The dealer also said what our front triple ring is and now I forget...)

The dealer offered to swap out either the rear cassette or the small chainring for the cost of the part, no labor. But now that I see that 11/40 is listed as stock on the web site, and we didn't discuss making any changes, I'm wondering if we should have to pay for the part. The bike has less than 100 miles on it, so it really is a brand new cassette. In any case, it's a full day's drive for us to go get it swapped out.

I'd appreciate any thoughts or suggestions on what's fair to expect. Thank you again!
So according to Co-Mo web site set up for drive train 50/34-11/40 the dealer can not possibly switch out your front 34 tooth chain ring with BCD of 110 for a smaller CHain ring that's as low as you can go. Call Dawn at CoMotion the owner @ 866 282 6336 explain the difference of what was specified on the website and the difference between what you've got. There is no reason for why you should be out any expense.
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Old 03-15-18, 03:45 PM
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Finally got home so I can verify what we have:

Triple in front: 52/39/30 (web site says double 50/34)
In the rear: 11/32 (web site says 11/40)

Our older bike has 26" wheels and is substantially heavier, so it's probably not an ideal comparison to the new bike, at least without doing more complicated math...

And I looked back at our paperwork...I have an email showing that we requested the stock cassette and chainring, but then on the actual order sheet it says 11/32. I don't know why it changed in between, and clearly we didn't catch it when the order was submitted.

I might call the Co-Motion folks just to talk it through, esp. the double vs. triple, but at this point, I'm thinking that our LBS is perfectly capable of doing the change (the dealer suggested not trusting others with the bike, but we have a mechanic who is a bit of a tandem nut so I think it would be okay).

Again, thanks so much for all the questions and advice -- this is all extremely helpful!
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Old 03-15-18, 04:54 PM
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That was the standard gearing for a speedster until recently. I think the 2017 still used the 10 speed triple. I would rather have that gearing then the newer 11 speed double. With your setup you can go to a smaller small ring cheep. When I changed mine I figured I've never wished my gearing wasn't so low so I put on a 24 tooth. Iv'e never regretted it. I don't use it very often but when I do I'm glad I have it. I have 2 Speedsters a 2010 tandem and a 2011 triplet. Booth years had 52/39/30 cranksets as stranded in 2010 an 11/28 cassette was standard in 2011 they went to an 11/32 as standard. I think they stayed with the 52/39/30 11/32 through 2017.
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Old 03-15-18, 06:39 PM
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Originally Posted by Kiramarch
Finally got home so I can verify what we have:

Triple in front: 52/39/30 (web site says double 50/34)
In the rear: 11/32 (web site says 11/40)

Our older bike has 26" wheels and is substantially heavier, so it's probably not an ideal comparison to the new bike, at least without doing more complicated math...

And I looked back at our paperwork...I have an email showing that we requested the stock cassette and chainring, but then on the actual order sheet it says 11/32. I don't know why it changed in between, and clearly we didn't catch it when the order was submitted.

I might call the Co-Motion folks just to talk it through, esp. the double vs. triple, but at this point, I'm thinking that our LBS is perfectly capable of doing the change (the dealer suggested not trusting others with the bike, but we have a mechanic who is a bit of a tandem nut so I think it would be okay).

Again, thanks so much for all the questions and advice -- this is all extremely helpful!
I would call this good news. Buy a 24 tooth ring and use it to replace your 30. Easily and inexpensively done by you or LBS. You will then have a very wide dynamic range with reasonable spacing, ideal for a tandem. Better than what Comotion or most other manufacturers offer today. It will still shift fine. Then go climb some hills and enjoy the descents.
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Old 03-15-18, 06:51 PM
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+1 on keeping the triple and getting a smaller granny gear. Youíre looking for a 74 bcd 5-bolt inner chainring - 24, 26, or 28T depending on how much lower you want to go. Itís a painless change compared to getting lower gears with a double.
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Old 03-15-18, 10:32 PM
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FWIW I doubt you could get the 11-40 to work with a triple. Too much chain to take up.
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