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I have a "normal" short wheelbase highracer recumbent bicycle (Radius Hornet I) for about 20 years now, so I'm generally used to recumbent-specific things. But since recently I also own an older, pre-owned (adult) KMX recumbent trike from the estate of a deceased friend. (Seems to be an KMX X-Class from 2003 to 2007.)

On the first tour with the trike, I noticed that, if I forgot to shift down on the front derailleur (labeled "Shimano Altus") in time before going uphill, I can't shift down anymore when already going uphill, because if I push into the pedals quite strong due to going uphill with a high gear, the chain just pulls the derailleur back into the position behind the biggest front gear, making shifting the front gears impossible until the hill is less steep again. (And I don't think that I'm too heavy for that trike with my about 82kg. :-)

Questions (and potential answers, but I don't know which of them might be the right one):

  • Is this normal because maybe standard derailleurs just aren't made (or weren't made back then) for the heavy tensile load which can easily appear on the chains of recumbent bicycles and especially recumbent trikes? (If that's a nowadays solved issue, I wouldn't mind recommendations.)
  • Or is this just a cheap derailleur which can't cope with that tensile load on the chain at all? At least Shimano says that the current Altus M2000 series is for first timers, i.e. probably rather cheap and not heavy-duty. (In that case, I'd be happy about recommendations for alternatives, too.)
  • Or could it be a cheap and too stretchy bowden wire?
  • Or is this something I can fix by adjusting some spring tension in the derailleur or so?

Additional information added after the first answer as there were some questions in there:

  • The trike had a "service" at some local bicycle shop just before that tour. So I assume the derailleur is neither too dirty no missing lube nor defect in general. It also worked under other conditions, despite not always perfect.

  • I usually ride the recumbent bike not in hilly areas as steep ascents are generally difficult due to keeping the balance is more difficult. So I never noticed such an issue with the recumbent bike even though while riding I see the front derailleur there, too. With the trike there's no need to keep balance, so hills feel like no more being an issue as long as my legs keep pushing into the pedals.

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This is normal for front derailleurs - they can't shift under heavy load because you're putting pressure on the chain, and the front mech has to push the chain sideways with enough force to overcome your leg muscles.
The only way to get a good shift is to back off the chain/leg pressure, and that's not easy if it has already become steep.

I'm taking it that your existing bike doesn't show the same reticence to change gears at the front on a climb? Next time you're riding, have a think about when you change gear - I wonder if the added stability of the trike is letting you get further into the grade before you shift down, whereas the recumbent bike needs the lower gearing sooner to help maintain balance.

Adjusting spring tension anywhere won't help, although a good clean and degrease then relube may help. It is also possible that the existing front derailleur is damaged somehow.

Also check the "gear inches" value for both bikes - it may be that the trike has different gearing and combined with the smaller wheel rims it simply needs to be shifted earlier on the climb. Something like https://www.sheldonbrown.com/gear-calc.html can be very helpful here.

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    Thanks! Indeed, I've never noticed this before, even though I also see the FD on my recumbent bicycle while riding. But going uphill with the recumbent bicycle is much more difficult (even compared to a normal bicycle), because I need to maintain some speed to keep the balance — not just more pedaling speed. With the trike I can just sit there and go uphill in a rather slow fashion. I can even stop and pause without unmounting. With the recumbent bicycle I'd likely have used a different way. The trike just came from a service, so I assume no issue due to dirt, missing lube or defects. Jul 17 at 3:31
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    Now that you mention it, I might have experienced at least the problem itself with my (classic) road bicycle some 20 to 30 years ago… But I've never seen a bottom/front derailleur so clearly moving in relation to how much I push into the pedal. Well, with the road bike, I usually don't look down but forward. :-) Jul 17 at 3:50
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    @AxelBeckert well, my 20/26 HP has a broken FD - The previous owner tried to shift on a climb and it broke a wee peg off. So I just used the limit screws to lock it in the big ring and my commute is flat other than three overpasses which are pretty gentle and short. Try shifting the front sooner, or back off the pedal pressure during shifting (it can help to get up some speed first. I suspect the stability of the trike is distracting you from the gradient. Try riding both bikes up the same climb and see how you tackle them. Recumbent riders tend to spin over mashing so aim for 80+ RPM.
    – Criggie
    Jul 17 at 4:39
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    Yep, experienced an often spinning rear wheel for the first time on solid ground (cobblestone on a steep ascent) with the trike, too. But there the reason was more or less obvious. The tadpole configuration has not much weight on the rear wheel. Leaning my head more backwards actually made the situation better. On loose ground I even managed to spin the wheel while still being on the biggest gear on the FD. %-) Jul 17 at 5:14
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    When I got my velomobile (normal trike tech inside) I asked the seller, (who is very experienced in riding these things) what to do if I got stuck in the wrong gear. His answer was 'get out and get it sorted'. I have asked helpful people for a little push so I could get the gear right.
    – Willeke
    Jul 17 at 9:07

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