How to stop chain slap (on a 20' Giant)????

[mtbdh_girl]

I am hoping someone here can help -

We have started doing a lot of off road riding - trails with lots of roots/bumps. My 5yo daughter is having a huge amount of trouble with chain slap - every time she hits a bump the chain really bounces around - enough to bounce her off the pedals at times.

Her bike is a stock 20' Giant MTX150 (boys version) w/ Shimano SIS derailleur etc (I can post a pic if this would help). What can we do to stop the cain moving so much? Is a new derailleur going to fix the problem? Are there any other options?

Thanks,
Cindie

 

[Turner_rider]

When you say that the chain is boucing her off the pedals do you mean that it is skipping accross the cassette (i.e. jumping between gears) and that is causing her to loose her feet when pedalling?

A different derailleur may fix the problem, but it may also be something she'll just have to get used to as she gains experience (i.e. she is only 5 and pedalling technique across roots bumps etc is bound to improve). Maybe a quick tune up to ensure the derailleur has the chain properly in gear and not on the edge of a change could also help, as well as some grippier pedals.

Good to see she's on the bike too

 

[alchemist]

The chain too long perhaps?

 

[takai]

What is the B-tension like on the derailleur? I had some issues on my old bike with the chain kicking back when the B-tension was too low.

 

[mtbdh_girl]

When you say that the chain is boucing her off the pedals do you mean that it is skipping accross the cassette (i.e. jumping between gears) and that is causing her to loose her feet when pedalling?

A different derailleur may fix the problem, but it may also be something she'll just have to get used to as she gains experience (i.e. she is only 5 and pedalling technique across roots bumps etc is bound to improve). Maybe a quick tune up to ensure the derailleur has the chain properly in gear and not on the edge of a change could also help, as well as some grippier pedals.

Good to see she's on the bike too

No, it's not skipping accross the cassette, just bouncing up and down - not changing gears or anything. The bike just had it's first service which didn't fix the problem either. Technique is not going to fix the problem - she's got front suspension and stands up to pedal through anything not flat - she gets bounced off the pedals whether she is standing or sitting. Pedals are already pretty grippy - bigger pins would just rip her legs/ankles up.

We got her riding early because it means we can ride more too!!!

The chain too long perhaps?

Will have a look at whether the chains too long but looking at the derailleur it is already sitting further forward than it does on our bikes.

What is the B-tension like on the derailleur? I had some issues on my old bike with the chain kicking back when the B-tension was too low.

What do you mean by B-tension? and how do I look/check that??



Thanks for your suggestions everyone.

 

[DWN-HLR]

this may sound a bit advanced for a 5yr old but most 60% of feet slippage is failure to use your legs as shocks as well like keeping them stiff wont help you need to be loose

 

[mtbdh_girl]

Fair enough, but she does bmx as well and gets some air - her feet don't slip when she lands that.

Also, riding behind her- you can actually see the chain tensioner on the rear derailleur bounce when riding over tree roots etc. When that happens, it lets the tension out of the chain and affects her pedaling.

 

[takai]

http://www.sheldonbrown.com/gloss_ba-n.html

That defines B-tension far better than i can. When i had the issue basically it was jamming into the casette and locking the chain up, which put pretty much the right amount of tension on the freehub to lock that up too, and thereby kicking back through to the pedals.

 

[LLuLukLuke]

Slapping

Take a link out of the chain. The derailleur will inevitably be pulling harder on the chain, thus tensioning it more.

 

[LJohn]

try pulling the wheel back a bit to put more tesion on the chain it will stop the bouncing around
and you should put a chain stay protector on to stop scratches

MTX150s are a small alloy hardtail with vert dropouts. Very popular bikes.

Chain slap sounds bad but won't bounce anyone off pedals.

dwn-hlr got it spot on. A BMX landing isn't repetitive bumps. Its one solid shock. Think of your legs as a damping system. You have to self adjust rebound and compression 'damping' to match the terrain. It is a little advanced for a 5 year old and unless you step up to a dually, your daughter is either gonna have to learn to absorb the shocks or ride less rooty terrain. And grippy pedals don't resist against vertical travel. That's for clipless. But if you put her on clipless, not absorbing the vibrations puts immense stress on knees.

So try to explain to her to keep her legs bent a little.

That's why people can ride downhill on a hardtail.

 

[stabbsy]

umm this thread is over six months old so i guess the problem has already been solved