Shimano 105 gears ... help

[narrowangle]

Hi... me again. Sorry. Right... went out again yesteray on my new road bike. Much better now seat down and forward a bit though still slip backwards (How do i tilt my sadle?).

Ok main question.... Twice yesterday my chain came off. This is a brand new Dolan Mythos with drop bars. Never experienced it with old flat handlebar road bike. Both occasions i noticed i was going from front big cog to smaller cog and on back cog i was on the big cog. (Confusing??)

Am i right in thinking it was because i went from big gear with low to low low??? That sounds stupid but i know what i mean. I discussed it with hubby tonight and basically i reckon that if u see a big hill and you know ur going to have to go to smaller front cog then u should anticipate that and swop the big cog to a smaller cog before uv gone all the way up to a big cog on the back gear.
I WISH I KNEW THE CORRECT TERMINOLOGY. Sorry but please help. Am i right???

 

[gavintc]

Having the chain in big ring at the front and the lowest gear (largest sprocket) is ill advised. Your chain is at an awkward angle and I suggest that when you change to a more conventional chain line that the deraileur is having problems with the angles. I propose that you only use the top 7 sprockets (the smallest 7) when on the big ring and the 7 biggest sprockets when in the small ring.

 

[narrowangle]

Thanks. Despite my jumbled post, you've confirmed what i meant. Great help. Thanks again.

 

[narrowangle]

Plus i have now learnt the word 'sprocket'

 

[fossyant]

You've hit the nail on the head there !

 

[peanut]

also you need to re-adjust your front mech. Even with the bad chain alignment mentioned by gavintc the chain shouldn't come off ever.!
Stick your bike upside down in the kitchen or somewhere warm and dry.
Put your chain onto the big chainring Adjust the front mech until the front face of the cage is exactly parralel to the big ring and precisely above the teeth.
Now make sure the cage is within 1-2mm max from the teeth of the big ring. Adjust accordingly.
Now spin the cranks and put the chain onto the small chainring..It shouldn't come off .If it does adjust the front mech stop screw in a bit until the chain will just about change down from the big ring to the small ring.
Hope this is helpful. Easier to do that to describe

 

[narrowangle]

Hmmmm. Right. Thanks. I am doing my first work commute on friday and then a triathlon the week after. But after that i will be taking it back for a service. So if i mention it they should sort it??? Not sure i can follow your instructions and im a real newbie so daren't. But your responce is helpful. So in the meantime i should do as Gavintc suggests. Don't want y chain coming off in dark whilst commuting or even worse during my sprint tri!!
Cheers folks. Great forum this. Very quick and friendly.

 

[gavintc]

We have all been there - there is no such thing as a silly question. It just takes time to absorb the nuances and detail. I have only been riding a road bike for about 4 years and am very much still learning.

 

[Scoosh]

Hi narrowangle and welcome to the marvellous and (often ) mysterious world of road bikes

Here's a link to a video tutorial site which is pretty good for explaining things - and showing you how to do them. On the same page there are links to Adjusting your derailleurs, so most things should be covered there.

Don't want y chain coming off in dark whilst commuting or even worse during my sprint tri!!

If in doubt, definitely take it along to the LBS and ask them to sort it before the tri, explaining why it is kinda important. I'm sure they'll understand