question on internal hubs and Downtube

[NJfolder]

I'm thinking of buying a Downtube and saw this on their site: You should never shift an internal hub bike under load, in other words back off the pedals when you shift. Can someone explain what that means? I'm guessing it means you shouldn't pedal as you shift, but I'm not sure. I have no experience with internal hub bikes. Thanks....

[Tovar]

That's right, to change gears you need to stop pedaling, good for people reduce gears on stop lights.

But not so good when you are climbing since you lost momentum.

Regards

[jur]

Internal hub gears do not shift well under pedalling torque: The torque holds the various gears and internal parts against each other with some pressure, making movement difficult.

The Sturmey Archer hubs will not shift under pressure at all (with the exception of 2 gears in one direction). To allow the internal bits to move, pressure on the pedals must be relaxed.

[Sammyboy]

In practise, you can *pre-select" the next gear you want, then back off the pressure for a moment so it shifts.

[NJfolder]

Thanks everyone for explaining. So then, what is the advantage of an internal hub if you can't shift while pedaling? Like Tovar said, you lose momentum up hills so I'm not seeing the advantage of this. I have a cheapo folder I bought off eBay about a year ago and it has just the usual dérailleur which hangs down kind of low so I can see where the internal hub would solve that problem, but is that the only advantage?

[Dynocoaster]

Advantage is no cassette or derailleur to get full of dirt or water and have to constantly clean. Chain maintenance is easier. I think it was stated better for city riding.

[Sammyboy]

You only lose a tiny bit of momentum, and you CAN shift when stopped - quite handy at lights.

[Tovar]

That's way I was thinking to upgrade my Downtube 8FS to a SRAM dualdrive, so with 3 internal speeds I can change at stop lights, get a better gearing for hills climbing and a better gearing for speeding.

Redards

[Richbiker]

Actually, this is good shifting technique for most cassette/derailleur systems as well. Backing off on the pedalling pressure while shifting reduces tension on the chain, and allows for a smoother, quieter shift, instead of a loud "crunch". Some folks drop their chain off the crankset while downshifting, because they wait too long until there's enormous tension on the chain and a very slow cadence. Only the top-end derailleur systems work well with a lot pedalling torque, because they are designed for racing.

[bicyclridr4life]

... pressure on the pedals must be relaxed.

But only for an instant. If you preselect the next gear you want the shift takes place faster than you can say "Quidditch". (Yea, I am 54 and a Harry Potter fan, so what?)