clunking gear

lauren

I have a new hybrid bike with 14 gears, which I'm pleased with for my
needs. However, gear number 7 'clunks'.

I took it for its 6 week check and when I mentionned the 'clunk' they
told me it is due to the chain being on the smallest cog at back &
largest at front, the cogs are furthest apart so it causes the chain
to become slightly twisted. The answer is to switch up or down to find
a similar ratio.

I asked whether the bike had a design fault and the answer was that
all bikes do this on a similar cog combination. Is this right - should
I just accept this or am I being fobbed off...?

Mark Tranchant

lauren wrote:

> I have a new hybrid bike with 14 gears, which I'm pleased with for my
> needs. However, gear number 7 'clunks'.
>
> I took it for its 6 week check and when I mentionned the 'clunk' they
> told me it is due to the chain being on the smallest cog at back &
> largest at front, the cogs are furthest apart so it causes the chain
> to become slightly twisted. The answer is to switch up or down to find
> a similar ratio.
>
> I asked whether the bike had a design fault and the answer was that
> all bikes do this on a similar cog combination. Is this right - should
> I just accept this or am I being fobbed off...?

This is correct. On older 5-speed machines, the chain offset in the
extreme gears was less, and all gear combinations may have been useable.

With today's wider cassettes, this is no longer the case. I can hear the
chain complaining in 7 of my 27 (3x9) gears: 7-9, 18, 19-21.

Have a read through this:

http://tranchant.plus.com/cycling/gears/

--
Mark.

David Kerber

In article <a3685b88.0405170200.2399f27d@posting.google.com>,
elaine@taylorr.com says...
> I have a new hybrid bike with 14 gears, which I'm pleased with for my
> needs. However, gear number 7 'clunks'.
>
> I took it for its 6 week check and when I mentionned the 'clunk' they
> told me it is due to the chain being on the smallest cog at back &
> largest at front, the cogs are furthest apart so it causes the chain
> to become slightly twisted. The answer is to switch up or down to find
> a similar ratio.

The big front/small rear has no similar ratio; it's the highest hear you
have. However, what do you mean by "clunk"? Mine always "clunk" once
going into gear (as the chain seats itself on the cog), but they should
be quiet after that.


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newsgroups if possible).

MikeYankee

>due to the chain being on the smallest cog at back & largest at front

That should not cause a problem if the bike is properly adjusted. However, the
way you describe it makes me think you may have misunderstood. Perhaps you
were using the BIG chainring in front with the BIGGEST (closest to the hub,
lowest gear) cog in back. That would quite possibly cause the drivetrain to
clunk in protest. It is unwise to use 'extreme' gear combinations. Using the
big ring with one of the bigger cogs puts too much tension on the chain,
degrades the chainline (pulls the chain at an angle), may damage the rear
derailleur, cause premature wear, etc. Using the small ring with the one of
the smaller cogs gives you too little chain tension, with less risk of damaging
components but more risk of dropping the chain.

If you have a '14-speed' bike you will find that roughly 10 of the gear
combinations are usable, which is plenty. Bikes are usually engineered so that
the extreme gear combinations are pretty much redundant anyway.


Mike Yankee

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To reply, delete everything after "com".)

Mark Tranchant

Mark Tranchant wrote:

> lauren wrote:
>
>> I have a new hybrid bike with 14 gears, which I'm pleased with for my
>> needs. However, gear number 7 'clunks'.
>>
>> I took it for its 6 week check and when I mentionned the 'clunk' they
>> told me it is due to the chain being on the smallest cog at back &
>> largest at front

Sorry to reply to my own post - gear 7, as you are defining it, is
smallest front and rear.

Smallest rear / largest front is "14th", and should not present any
problems.

--
Mark.