Chain Tensioner advice needed

[gds58]

I'm in the process of building a single speed fixed gear bike using an aluminium road bike frame. The frame has the now common place short vertical dropouts so there is no fore and aft adjustment on the wheel position in order to get the correct chain tension. I've been told that I will need to fit a chain tensioner and I've found a number for sale on ebay but I wanted to hear from all you guys on what you think is the best type and if they work properly on a fixed as opposed to a single freewheel. I don't suppose that it will make much difference but I'll be running a 42 x 15 set-up with an option to go to 39 x 15.

I'll look forward to the floods of replies!!

Graham

 

[wheres_my_beard]

I have a singlespeed with a Tension Seeker (similar to the Surly Singleator) chain tensioner, and it just about does the job but it a total PITA to set up.

I would reccomend getting one that is not tensioned using a "spring", but one that fixes firmly in position bolted to the deraileur hanger. (The "spring" i got with my tensioner (which wasn't cheap) was shocking; under tension it did not properly resist the tension and spring back, it just bent. This was during initial installation.)

This is the Gusset Bachelor Tensioner which is very reasonably priced.

I don't know how well any chain tension devices stand up to use on a fixed gear, but should be up to the job, depending on how hard and far you ride.

As suggested on other threads, there are other options with varying costs and challenges linked to them;
- eccentric bottom brackets and hubs to take up slack;
- filing the dropout to allow some lateral movement to take up slack;
- finding the "magic" gear ratio * (front and back cogs) so that the chain length magically fits your (specific) frame with minimal effort.
- Half link chains can help with any of these solutions to allow more control of the spare chain length.

Hope this helps

* You can acheive the same gear ratio/ gear inches using varying cogs to acheive a chain length that works for you.
for example, 52 x 20 may produce a more convenient chain length than 39 x 15 (both have ratio of 2.6 and gear inches of 70.2).

 

[MacB]

My understanding, and other may correct me here, is:-

Fixed - chain tensioner is a no-no as are the mini EBBs(Excentriker, Forward Components and Phil Wood) that fit standard bottom bracket shells. You can try to get the right ring/cog combo using this:-
http://eehouse.org/fixin/index.php
and there's also the ghost(I think) ring, so you set ring/cog and chain as close as you can and then have a floating chainwheel in between the chain, it will move forward and backwards to adjust tension....I've never tried this but have seen piccies. I've also seen Sheldon Brown stuff on filing the dropout to give some tension ability.

SS - any tensioner(or an old rear derailler), the Surly or the Pauls Engineering Melvin get good reviews, or one of the mini EBB's, these require an Outboard Bearing Crankset and provide about half the adjustment of a full eccentric, but you can use a half link in the chain if need be - I use the Forward components one for a hub gear and has been excellent, but not cheap. However it's currently out of production pending a new model which is meant to be able to work with square taper as well. As is the, seen and reviewed, but not appeared Phil Wood Lil Phil eccentric. There's also an eccentric hub but I have no experience of that, it seems to be a bit of a marmite thing though, either loved or hated.