CHANGING 50T TO 60T ON COMO (PROBABLY APPLIES TO LEVO, KENEVO, VADO)

[WilliamBenner]

Hi everyone,

I'm a mechanical engineer, but completely new to e-biking.

I recently purchased a Turbo Como 5.0 with Gates Carbon Drive. It came with 50 tooth front sprocket, but felt like the bike was geared too low and figured I'd change the sprocket to 60 tooth. Unfortunately the 60 has 5-spoke and 130BCD, while the original 50 has 4-spoke and 104BCD. See the picture below where I'm holding the 60 tooth in front of the 50.

I found, and then purchased an adapter from Ti Cycles:

104mm to 130mm BCD Adapter — TI CYCLES FABRICATION

104mm to 130mm BCD ADAPTER This one was a tough nut to crack! Ideal for pairing larger 130BCD Gates Carbon Drive rings with wider 104BCD cranks for optimal performance on Rohloff Speedhub's outboard drive line. * Available as adapter only or as adapter with 7-piece SS chainring bolt set.

www.ticycles.com

I think for some applications this adapter would be perfect as they designed it, but I had to modify both the adapter and sprocket to get it to work perfectly. It was a little bit tricky, but I figured it out. Below is a picture of the bike with the 60-tooth sprocket installed.

As I mentioned, it was a little bit tricky. Since the information about this isn't available anywhere, I decided to make a video that discusses all of the issues and what I had to do to fully implement it. You can see the video here:

Let me know if you have any questions about this. I'd bet curious to hear what you experienced folks think of this.

Best regards,

William Benner

 

[WilliamBenner]

WOW, changing from 50-tooth to 60-tooth had a bigger impact on my top speed than I imagined!

Actually, some kind of GPS error, but it was funny...

 

[Stefan Mikes]

How did the swap affect the climbing ability of your Como, William?

(PROBABLY APPLIES TO LEVO, KENEVO, VADO)

Only Como IGH, Vado IGH, and Como SL are IGH/carbon belt e-bikes. Levo and Kenevo are e-MTBs, and these use the chain/derailleur. Other Specialized e-bikes such as Tero and all SL e-bikes save Como are derailleur e-bikes, too.

 

[WilliamBenner]

How did the swap affect the climbing ability of your Como, William?

Well the point is that the Enviolo can have lower (virtual) gears too, so anything that was possible with the 50 is still possible with the 60, but the reverse is not true. Now it's easy for me to go 25, and possible to go 28. Before it was hard to go 25 and nearly impossible to go 28. Only 20 was "easy"...

Only Como IGH, Vado IGH, and Como SL are IGH/carbon belt e-bikes. Levo and Kenevo are e-MTBs, and these use the chain/derailleur. Other Specialized e-bikes such as Tero and all SL e-bikes save Como are derailleur e-bikes, too.

AHA thanks for the info. I've seen some MTBs that use Carbon Drive so I assumed Specialized had some too.

 

[Stefan Mikes]

Well the point is that the Enviolo can have lower (virtual) gears too, so anything that was possible with the 50 is still possible with the 60, but the reverse is not true.

Now, it is hard to understand for me. Enviolo has some gearing range (380%?) If you (dramatically) increased the chainring size then yes you have improved the high-end but you had to degrade the low-end at the same time. While it is very easy to determine the gearing ratio or gear-inches with the derailleur system, it is not clear to me what it means for the IGH.

Let us discuss the chainring size effect for my Vado 5.0 with a 11-46T cassette (gearing range of 46/11 = 4.18 (418%)) equipped with 29x2" (50-622) wheels.

Mountain gearing, a 38T chainring

• The granny gear, 38-46T. Gearing ratio: 0.83. Gear-inches: 23.6.
• The top gear, 38-11T. Gearing ratio: 3.45. The speed achieved at the cadence of 80: 23.4 mph

Road gearing, a 48T chainring

• The granny gear, 48-46T. Gearing ratio: 1.04. Gear-inches: 29.6.
• The top gear, 48-11T. Gearing ratio: 4.36. The speed achieved at the cadence of 80: 29.6 mph (theoretically, or downhill)

By increasing the chainring size, the top-end has dramatically improved (23.4 vs 29.6 mph). However, the climbing capability had dramatically degraded. For your information, the MTB-worthy granny gear starts at 20 gear-inch (the lower the better for climbing). Also, gearing ratio below 1 is where you are getting the leverage of gearing for steep climbs. (The 48T chainring here makes the bike not really good for steep hills).

Even if Enviolo has some "virtual gears" William, you as a mechanical engineer know that it is not possible to cheat the laws of physics; improving the top-end always degrades the low-end of gearing, Enviolo or a derailleur, as both are geared solutions. Do you agree with me now?

I've seen some MTBs that use Carbon Drive

No respected MTB brand offers Carbon Drive/IGH as it has been not embraced by the MTB community. And Specialized is a world leader in MTB, and especially in e-MTB.

Main reasons for not using the Carbon Drive/IGH on a Mountain Bike are:

• Typically, lower gearing range of the IGH
• The heavy weight of the IGH, not only making an MTB heavier but also shifting the centre of gravity rearwards
• Difficult to remove the rear wheel for a field-repair
• Susceptibility to twigs and pebbles.

 

[Cavalo]

Now, it is hard to understand for me.

Let me attempt to clear up the confusion… signature says he lives in Orlando FL. There is nothing resembling a hill for 300mi in any direction from where he lives. It was a subjective statement about going to larger primary ratio making no difference for climbing... because there is no climbing in that part of the world outside of elevated bridges, just head winds. So raising the lowest ratio 20% is unnoticeable. ;-)

 

[Sefutau2020]

Hi everyone,

I'm a mechanical engineer, but completely new to e-biking.

I recently purchased a Turbo Como 5.0 with Gates Carbon Drive. It came with 50 tooth front sprocket, but felt like the bike was geared too low and figured I'd change the sprocket to 60 tooth. Unfortunately the 60 has 5-spoke and 130BCD, while the original 50 has 4-spoke and 104BCD. See the picture below where I'm holding the 60 tooth in front of the 50.

View attachment 132925

I found, and then purchased an adapter from Ti Cycles:

104mm to 130mm BCD Adapter — TI CYCLES FABRICATION

104mm to 130mm BCD ADAPTER This one was a tough nut to crack! Ideal for pairing larger 130BCD Gates Carbon Drive rings with wider 104BCD cranks for optimal performance on Rohloff Speedhub's outboard drive line. * Available as adapter only or as adapter with 7-piece SS chainring bolt set.

www.ticycles.com

I think for some applications this adapter would be perfect as they designed it, but I had to modify both the adapter and sprocket to get it to work perfectly. It was a little bit tricky, but I figured it out. Below is a picture of the bike with the 60-tooth sprocket installed.

View attachment 132926

As I mentioned, it was a little bit tricky. Since the information about this isn't available anywhere, I decided to make a video that discusses all of the issues and what I had to do to fully implement it. You can see the video here:

Let me know if you have any questions about this. I'd bet curious to hear what you experienced folks think of this.

Best regards,

William Benner

Well done. I agree, the 50t is too small....it should have come with a 60t for greater top speed.

 

[sanyata]

Assuming the splines on the motors are the same between the Como IGH and other derailer models, not necessarily just Como's, would it have been possible to just buy the 5 spoke, 130 BCD spyder from Specialized and replace the 104 BCD? I don't know the Como specs, so I'm just spit balling' here.
The Specialized 5S, 130 BCD spyder (a Creo part) was $25 USD last summer when I bought one to replace the 4S, 104BCD on my Vado SL. It was a straightforward swap and more elegant than using an adaptor.

 

[scrambler]

Changing from 50T to 60T without reducing the rear sprocket increases the belt path length, and Gates only has a discrete number of sizes.

You may want to clarify if you had to get a longer belt that fitted within the wheel adjustment available.