I’m trying to replace as many of the plastic parts on my Brompton as possible. I don’t like plastic on my bikes. This doesn’t mean that plastic parts don’t do the job they are made for. It’s more a question of personal taste.
I found a custom chain tensioner from BikeFun. This one fits on 2/6-speed Bromptons. Brompfication copied the concept but their nice looking tensioner works only with 1/3/5-speed Bromptons.
Here it is – a large piece of plastic… no complains about it’s function, but the visual aspect stands back behind my expectations.
Easy to remove. We will need some parts of the old chain tensioner. The two wheels and the spring inside of the tensioner. The first thing to do is to remove the small caps on the wheel axis to get a look on the screws holding the wheels. Use a screwdriver to pull them out.
Unscrew both chain tensioner idler wheels and keep the washers you find too. If the wheels are outworn get new ones! If you remount them later use the washers in the same place as you found them here.
Remount both wheels on the new chain tensioner. Don’t forget the washers and do not overtighten the screws. I use Loctite threadlocker to secure the screws.
Now disassemble the two parts of the tensioner. You need the spring for your new beauty. The top of the spring is symmetric to the bottom.
Insert the spring in the new chain tensioner. Watch the nut for the spring – but it is nearly impossible to go wrong. Now screw on the other leg of the tensioner. Everything should move freely without any resistance.
What a nice piece of craftsmanship – isn’t it? With a quote from Heraclitus. Wow.
And here we have the new look of my Brompton. Again less plastic on the bike. I like the new chain tensioner a lot.
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12 responses to “A Custom Chain Tensioner”
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Detlef, that is quite beautiful! I wonder about the extra weight, though, when carrying the Brompton; Brompton’s use of plastic is driven, I’m sure, by the deisre to keep the weight down. But I can see that the improves aesthetics alone could justify the change!
oh – there is not too much added weight with the aluminum tensioner. You don’t feel it when carry it. Forget to put it on a scale before mounting it – but it could be less then the original part too.
BikeFun writes: 149g for their tensioner. The Bromtpon plastic part should have 151g (Brompton component weights table).
No difference at all then — wow!
And several grams less in my pocket ;)
Hi Detlef,
how did you order those parts of BikeFun? I did not find their web shop, where I could order in English.
Regards
Hartwig
Just send an email to the BikeFun guys – works fine that way.
You find the link to the website in my link collection in the right column.
Detlef
Beautiful piece; I just cannot get past the quote: “The only eternity in this world, but change.” That is just not correct.
Brompfication has just released an aluminium chain tensioner in 2/6 speeds:
http://www.brompfication.com/49-chain-tensioner-2-6-speed.html
I think that i like it better than the Bike Fun version, in part because it doesn’t have any logos or branding on it.
I like the finish of the Bike Fun version – including the text on the tensioner. But that’s a matter of taste.
Just found your blog and love it. Lots of good info.
I just got the Brompficaiton hinge clamps, Titanium extended seat post and nice wheels. Since they are going out of business, looking to get as much as I can while I can.
Just wondering how your bikefun chain tensioner is working three years later and did you notice an improvement in the shifting? I have heard the Brompification one imroves shifting, but haven’t run across any good reviews yet.
Thanks,
Ty Smith
San Francisco Bay Area
Hi Ty,
the tensioner still works fine – I don’t think any of the 3rd party tensioners improves the shifting at all. OK – it metal and no plastic anymore – but there are so many shifting components on the brompton that would need an improvement…
Best,
Detlef