Shimano Revoshift twist grip unusably tight

I assume your daughter was able to operate the gears fine before the bike was serviced. In that case, the shop broke your bike and it's absolutely their responsibility to fix it. Since you've had no joy from the mechanic, I suggest you speak to the manager about it: your key contention is that your daughter could operate the bike before they worked on it, and now she can't.

Unfortunately, if they still refuse to do anything about it, you probably can't do much more than leave bad reviews, and go to another bike shop: it's unlikely to be financially viable to sue, for example. I'd also note that $100 sounds like a lot of money to replace a low-end Shimano shifter, assuming you mean US dollars. The shifter itself costs $15-20, and fitting it shouldn't be anything close to $80 worth of labour.

As per AndyP’s comment, I have also heard anecdotally that these styles of shifters can be stiff for children’s hands, but then again some thumb push trigger shifters can feel quite stiff to my adult thumbs.

As you mention it is most difficult for your daughter to access first gear, I would investigate or have the shop check the Lower Limit screw on the derailleur. If this is set a fraction too tight then the shifter is trying to pull tension against this limit. If this screw is set too tight then the shop should adjust it to the correct position as part of the labour you’ve already paid for. It’s probably only a fraction of a turn.

Otherwise, changing to a trigger shifter unit needn’t be very expensive, but I would try models out and find which suits your daughter’s hand strength the best. if you’re quoting AUD price then maybe it includes the part cost and a minimum labour charge and that’s how much it costs to have work done on bikes where you are.

It has been suggested by an anonymous edit, from a person who had a similar problem, to double check the cable placement at the derailleur fixing bolt. For example this extract from the Shimano Tourney Dealer's manual

The fact that the shifter was operable before the service implies something was changed in the set up of the shifter or derailleur that has made it stiff.

You can do some quick checks to see if the shifter itself is stiff, or the cable or derailleur are preventing it from moving somehow.

With the shifter in the top gear, hold the rear wheel off the ground, pedal, and manually push the derailleur cage towards 1st gear (you'll probably need someone to help you do this, and be careful not to catch you fingers in the chain). The derailleur should go all the way to first gear easily.

With the derailleur pushed all the way to first gear - which takes all the tension out of the cable - does the shifter turn more easily?

My suggestion:

See if the cable routing at the derailleur has been changed - sharp turns / kinks could affect the shifting.

I'd also take a look at page 9 of this dealer document:

https://si.shimano.com/pdfs/dm/DM-SL0002-03-ENG.pdf

While this may not be the identical shifter, and the adjustment procedure describe pertains to the front, cable tension might be a factor for the rear, as well. Keep in mind that adjusting cable tension may change the indexing (where it cleanly shifts into gear), so you may need to adjust this as well.

You may want to pick this up, too: https://www.amazon.com/Bicycling-Complete-Bicycle-Maintenance-Repair/dp/160529487X

Very useful book, has saved me hundreds of dollars doing my own routine maintenance, and not having to run to the shop for every minor thing.

Best of luck - let us know how it goes!

I had a similar experience with my son's bike. The front derailleur gripshift was so stiff, he couldn't change gears without getting off the bike and then using 2 hands to twist the gripshifter!

The tip above from Swifty made me look carefully at the cable routing. I realised that my son's bike's cable was routed UNDER the metal protrusion rather than over it. This shifted the moment of leverage closer to the axis and hence made it harder to move the derailleur.

Once I rerouted the cable to go OVER this metal protrusion, whilst I wouldn't say shifting was EASY per se, it was a lot better and my son was able to shift his front derailleur again.

Follow the gear cable to the back of the bike until you come to the nut that holds it, pinch the cable with a set of pliers and undo slightly the nut. Let it off a tiny bit and retigten the nut to hold the cable.

Try the gear shifter on the handlebars, if it is still tough to shift, repeat the process. If it's too easy, tighten the cable a touch.

Worked for me,

Hope this helps!

I would contact Shimano. I've used Shimano for decades and this problem surprises me. Shoddy assembly and incompetent, uneducated, service personnel can derail the best of equipment.

My usual approach is to obtain the mailing address of the Corporate Office, and the name of the CEO. This has always resulted in the outcome I want. This should be an excellent bike, not the high end IBOC MONGOOSE of the 80's and early 90's but still a cut above comparably priced bikes.

My 5yo daughter has the same issue with tourney / revoshift. Tourney I bought new and revoshift is clean, correctly routed and lubed. As recommended I bought for 5€ this and I recommend you to.do the same.