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Genesis Flyer Fixed Chainline - Madison's reply

jhclarejhclare Posts: 19
edited September 2007 in Road general
Hi all, I have recently had a fixed sprocket fitted to my Flyer and the chainline is way off. Below is a response to an email I sent to Madison, the parent company of Genesis.

I'm stll not clear what I need to do to fix the problem, but I've included it here for others that may be having the same problem.

Regards,

John

--

Hi John-

The fixed sprocket was included with the last batch of 07 models due to
an error at the factory - it is supplied as standard with the hub so
they included it in the box. We asked them to leave it out - a 3/32 18T
option wasn't available from the supplier. So the forum's aren't quite
correct, this won't affect chainline - it simply won't work, but we
didn't intend this part to be supplied with the bike. Apologies for any
confusion caused.

The chainline isn't perfect to the millimetre partly due to the chainset
supplied - a perfect chainline would mean fitting the ring to the
central position of the tabs on the Sugino chainset. For pricing reasons
we (and other manufacturers) use a double with a single ring attached,
but the 1-2mm this puts the ring out is no problem. The chain will only
be liable to unship if run too slack, a mm or so +/- won't cause this in
itself.
We have found the hub to be sensitive to differing fixed sprockets -
using the one mistakenly supplied puts the chainline out, but other
models such as Surly seem to give a better line, as if it is at the edge
of, rather than the middle of, the varying positions a fixed sprocket
sits (can vary by a few mm). The hub positions the sprockets differently
dependant on which side, I think this is to do with tolerances between
hub, freewheel and fixed sprockets.

What brand of fixed sprocket do you have fitted currently?

Regards,

James Olsen

Product Manager



Original Message
From: John Clare [mailto:[email protected]]
Sent: 09 September 2007 14:12
To: Contact
Subject: Re: Ridgeback Message - Tue 29 May 07 - 16:24


Hi,

An update to this issue...

It seems that the Flyer is supplied with a 1/8 fixed cog, when the
rest of the drive train is 3/32. It seems a general consensus on
numerous bike forums that this could play a part in an imperfect
chainline with the Flyer.

I finally got my bike shop to fit a fixed sprocket (not the Genesis-
supplied one, as Evans didn't supply it due to above issue), and
indeed, the chainline is at least 4mm out, which is quite a lot, and
very noticeable. The chainwheel is further out than the sprocket.

Fixed riders have stressed the importance of a perfect chainline,
particularly when riding fixed, and I'm very disappointed with this
bike, seeing at it advertised as being fixed-ready.

As it is, I understand that the drive train will wear out much
quicker, and that the chain could even come off in some instances,
something that is very dangerous when riding fixed!

The chainline is perfect on the freewheel side, so I cannot
understand how such a basic requirement could have been overlooked on
the fixed side. Maybe the problem is the flip-flop hub?

I would appreciate a solution to this problem, and some form of
compensation for the time, money and effort spent in trying to
resolve this. The bike should work on both sides of the hub, as
advertised.

Regards,

John Clare

Posts

  • I agree you shouldn't be expected to do this out of the box, but moving washers around on the rear axle is a start, possibly a skinny spacer under the cog, also consider all the different cog brands which have slightly different dimensions...

    see http://www.businesscycles.com/tr-refspec.htm for a fairly comprehensive set of dimensions to help you get your chainline right.....

    Good luck!
    If you're as fat as me, all bikes are bendy.
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