I have two singlespeed 20" folders with BMX freewheels and do a lotta back wheel pulling to fix flats, etc. One of these is a real mother--on reinstalling a new rim the axle won't stay put in the dropout. So i always end up with wheel uncentered / chain slack.
So in desperation i tried turning the seatpost backwards, sitting on the bike, & tightening the axle nuts with my whole weight on the back wheel while holding the wheel straight in the frame w. the other hand. It worked, but i still have no control over the chain slack.
Am i missing something here? Some savvy move or technique?
This is usually due to the drop outs being damaged, either the slot has opened up or the plate is bent, or the face of the nuts are damaged.
If it's the drop out, careful use of a hammer can usually correct it, gently tap the plate back into place as required, do not do this on a cold day, or preheat the metal slightly, a hair dryer will do.
I have done this many times and never had a breakage, but it is possible.
I would replace the nuts in any case, with good quality track nuts with an integral washer, you can also fit tensioners like these if you have BMX style drop outs.
Note thread size can be either 3/8" or 10mm, you need to be careful about this as 10mm will fit on 3/8" and appear Ok but will fail under load, 3/8" will not fit on 10mm, so I always try a known 3/8" first, if it fits, OK, if it doesn't then you need a 10mm.
Sounds like great info. The two black axle tensioners shown on the right look interesting but my frames are non-BMX folding bikes. Now i'm off to ebay in search of axle tensioners assuming that's what they're officially called. If not, i'll be back to ask for the right search word. Thanx a bunch!
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
In the meantime i found 2 secondhand but flimsy tensioners that fit non-BMX. On these, a single horizontal adjustment bolt butts up directly against the rear frame, without the clamp as pictured above. So this seems to be the general way to go.
Another question--(shd. i B staring a new thread?)-- This new rim is threaded on both sides, so i cd. theoretically mount another freewheel on the other side. The active one is a 16 tooth as the chainring is only 32. I'd like a 15 since an 18 moves too slow. But Sheldon Brown says the 15s have offset ratchets due to the smaller diameter. Does this change the chain line to where i'd need spacers?
OK, looks like i can forget that. Front chainrings are too expensive.
All the chain tensioners i've asked about on ebay are for BMX rear-facing dropouts only. Even the ones with forward-facing adjust bolts have come back as BMX only (the scans don't show both sides.)
is there any such thing as a tensioner that will work on a forward-facing dropout frame?
![[-]](https://forums.bikeride.com/images/flatty/collapse.png "[-]")
