Pedals slipping/clunking when changing from small to big gear on BB

Mrdini

Regular
This is probably one for a LBS but thought I'd ask in here first to have a better idea whats going on & to understand how best to explain to the LBS (if its not something I can sort myself)...

So I have a Specialized Diverge with Tiagra gears. Sometimes when I change from the small cog up to the big cog on the front BB, the pedals feels like they're slipping/clunking for a few metres until it catches and changes gears. It doesn't always happen - changes seems a little better when on flats/downhill and if I freewheel a bit during changing gears. I suspect there's something going on in the rear derailleur but not sure what...

Or is this normal when shifting from small to big? I took my bike to the (not so local) LBS where I bought the bike for the bike's 6 weeks maintenance and mentioned it to them but although it was a little better afterwards, its still happening. I'm a little reluctant to go there again due to their location so would likely need to take it to a properly-local LBS if its an issue I can't resolve myself. (FWIW, they do have another more convenient store, but that location doesn't have a workshop as far as I know).

Thanks in advance for any thoughts!
 

mcshroom

Bionic Subsonic
If you mean that changing between from the little ring to the big ring at the front feels weird, then that sounds like the front derailleur is a little slack to me.

I doubt it's something at the back that's an issue. If you've got a barrel adjuster in the system, have a go at tightening it half a turn or so, and see if it makes a difference. This video might help you: -

View: https://www.youtube.com/watch?v=Ea03ChN-7Vg
 

alicat

Legendary Member
Location
Staffs
Yes, ease off a bit when changing at the front (especially when changing to the big ring). That means that going up a hill you should change to the small ring early or just tough it out and leave the front derailleur alone. You do know that most of your changing should be using the rear derailleur alone?
 
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Ajax Bay

Veteran
Location
East Devon
A tad more tension in the FD cable should make the small chain ring to large chain ring change crisper, and anyway ease off for just a moment while changing either front or rear.
 

nickAKA

Über Member
Location
Manchester
My tip changing into the big ring: as previously mentioned soft-pedal, don't try putting the power down, then keep the lever pressed in until the gear is properly engaged on the chain.
 
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boydj

Guru
Location
Paisley
Which cog you are on at the back can make a difference to the feel of the change at the front. Best to make the change before you get on to the smaller cogs so the angle of the chain is not too extreme.
 
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