Dechaining on the front cog

[Croydonian]

Anyone got any ideas for a small problem on my new Rapid 2 (just done about 250 miles) - I change up to the top front cog and the chain happily slips past the teeth and off.

It has happened twice - on my last two journeys. It is a pig to replace, as - no matter what I do when I feel the chain go, it wedges itself between the crank (?) and the cog. It is also making a fair mess of the face of the cog.

Should I just bring forward the promised first service to adjust the cables or am I doing something wrong in changing up?

 

[bobones]

You just need to tighten the top limit screw so that the cage doesn't move too far out. According to Google you have a Shimano R453 front derailleur in which case the top limit screw is the one farthest out from the frame. Put the chain in the smallest cog at the back and the largest at the front. The chain should just clear the outside plate of the derailleur so tighen this screw to push the cage back toward the frame so it's clearing the chain just and no more (< 0.5mm). See the Shimano Techdocs for full details. The principle is exactly the same even if you don't have a R453 FD, but you might have to identify which limit screw is which.

 

[Banjo]

+1 To what bobo said ,I find its best to release the cable from the clamp first ,adjust the screws so you have just enough clearance without the chain rubbing on the derailleur arm you can move the derailleur mech with your fingers to check its travelling thje full distance ,reconnect the cable and adjust the cable tension so theres no slack when on small cog as a start point then adjust the tension until it shifts up and down nicely.

If you live close to the shop you bought it from they would probably do it for you in about a minute. Leave the first service as long as youi can to give the cables chance to stretch and bed in before the final adjustment.

 

[Croydonian]

Thanks for the help, both. I am and probably always will be nervous about those little adjustment screws on derailleurs. If I can't stop by the shop on the next commute (Friday) I'll have a bash at the weekend.

 

[mickle]

Anyone got any ideas for a small problem on my new Rapid 2 (just done about 250 miles) - I change up to the top front cog and the chain happily slips past the teeth and off.

It has happened twice - on my last two journeys. It is a pig to replace, as - no matter what I do when I feel the chain go, it wedges itself between the crank (?) and the cog. It is also making a fair mess of the face of the cog.

Should I just bring forward the promised first service to adjust the cables or am I doing something wrong in changing up?

You are not doing anything wrong, it's a clear case of incorrect front derailleur set up. It's covered by warranty, including the scratches. Do not touch a thing and stop riding it immediately (or at the very least stop shifting) and take it back to the shop. You are completely entitled to have the damaged parts replaced.

If you fanny about with the front mech limit screws - particularly if you don't know what you are doing - the shop could, quite reasonably, refuse to honour the warranty.

And if you have any trouble with them refer them to me. Seriously.

 

[mickle]

Thanks for the help, both. I am and probably always will be nervous about those little adjustment screws on derailleurs. If I can't stop by the shop on the next commute (Friday) I'll have a bash at the weekend.

Can I just say again. Do not touch it, take it back to the shop and glare at them until they agree to adjust the mech correctly and replace the damaged parts. Their assembly failure damaged your bike (and could have put you under a bus) don't let them fob you off.

 

[Croydonian]

Thanks Mickle. I have spoken to the shop. I am not on the bike today but was planning to use it tomorrow. If I do, I will simply stick on the middle cog. Thank you for the advice. I fear that is all too easy to think I must have been causing the issue/problem by dint of poor technique or mis-use.