adding chainring to Trek 400

[Alonzo Lewis]

On an old Trek 400 series sport-tour bicycle, I want to install an additional chainring (somewhere
in the low 30t range) so the bicycle can be used for moderate touring. Is installing only one
chainring to the existing rings possible or will installing a whole arrangement be necessary? If
possible, what type of technical issues do I need to be cognizant of? For instance, will the front
derailleur be of concern? bottom bracket? gear cluster?

Your insight is much appreciated.

 

[Dan Brussee]

In article <[email protected]>, [email protected] says...
> On an old Trek 400 series sport-tour bicycle, I want to install an additional chainring (somewhere
> in the low 30t range) so the bicycle can be used for moderate touring. Is installing only one
> chainring to the existing rings possible or will installing a whole arrangement be necessary? If
> possible, what type of technical issues do I need to be cognizant of? For instance, will the front
> derailleur be of concern? bottom bracket? gear cluster?
>

If it is possible, the following will need to be considered:

1. Is there holes (threaded?) to mount the new inner chainring?
2. Is there room between the existing inner chainring and the frame to put another chainring? You
may need to install a longer bottom bracket.
3. Will your front derailleur move inward enough to shift to the new chainring (assuming you use the
existing BB)?
4. Will your rear derailleur handle the extra chain that will be spooled off when shifting to the
new chainring?
5. Will your current shifter handle the extra cable needed to swing your front derailleur the
extra distance?
6. Will your current front derailleur handle the difference in chainring size without dragging along
it's crosspiece?

--

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[Paul Southworth]

In article <[email protected]>, alonzo lewis
<[email protected]> wrote:
>On an old Trek 400 series sport-tour bicycle, I want to install an additional chainring (somewhere
>in the low 30t range) so the bicycle can be used for moderate touring. Is installing only one
>chainring to the existing rings possible or will installing a whole arrangement be necessary?

It is probably not possible/practical to add a third ring to the existing crankset.

> If possible, what type of technical issues do I need to be cognizant of? For instance, will the
> front derailleur be of concern? bottom bracket? gear cluster?

I think what you'll need are a crankset, a bottom bracket that matches it, a front derailleur
designed for the size chainrings you intend to use, derailleur cable. If the rear derailleur is a
short cage design, you'll probably need to replace that as well. Chain is a possible requirement as
well depending on the gearing you end up with and the rear derailleur.

You're probably looking at around $125 in new parts at the very minimum (ie, discount mail-order
purchase) and probably over $200 if you have a bike shop supply all necessary parts and labor.

--Paul

 

[Alonzo Lewis]

Guys, thanks for your input. The information is very helpful.

Alonzo

"Dan Brussee" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>, [email protected] says...
> > On an old Trek 400 series sport-tour bicycle, I want to install an additional chainring
> > (somewhere in the low 30t range) so the bicycle
can be
> > used for moderate touring. Is installing only one chainring to the
existing
> > rings possible or will installing a whole arrangement be necessary? If possible, what type of
> > technical issues do I need to be cognizant of?
For
> > instance, will the front derailleur be of concern? bottom bracket? gear cluster?
> >
>
> If it is possible, the following will need to be considered:
>
> 1. Is there holes (threaded?) to mount the new inner chainring?
> 2. Is there room between the existing inner chainring and the frame to put another chainring? You
> may need to install a longer bottom bracket.
> 3. Will your front derailleur move inward enough to shift to the new chainring (assuming you use
> the existing BB)?
> 4. Will your rear derailleur handle the extra chain that will be spooled off when shifting to the
> new chainring?
> 5. Will your current shifter handle the extra cable needed to swing your front derailleur the
> extra distance?
> 6. Will your current front derailleur handle the difference in chainring size without dragging
> along it's crosspiece?
>
>
>
> --
>
> Remove NOT from email address to reply. AntiSpam in action.