My brother in law has just bought a Charge Plug from Wiggle. When pedalling it gets noticeably stiffer at the same point each rotation of the cranks.
If you look directly down on the chain ring when pedalling it seems to wander a little – a couple of mm perhaps.

What’s it likely to be? A bent bottom bracket or a bent spider maybe?

Chances are he’ll send it straight back as it’s brand new but it’s a a hassle and wondered if it was there was an easy remedy.

Sounds like the BB might not be fitted straight. Could be cross treaded or frame needs facing. I’d send it back, or see if wiggle will pay for you to get it sorted at a LBS as may be cheaper / easier than sending back

Thanks, yeah I wondered if Wiggle might be willing to do that – worth asking to save sending it back.

The most obvious cause of that would be a bent chainring. Take it off and lay it on a flat surface, if it’s flat you’ll know it’s something else.

It’s a single speed or hub gear?

Apart from ring that has been bent in the post cChainrings often do not run fully concentric so you can get a point on a single speed/fixie/hub gear where the chain gets tight. Unlike a bike with an rear dérailleur where the spring absorbs any run out.

First thing to do is take the back wheel out and drop the chain. Check the BB is not binding. Put the wheel back in and check the wheel bearings (shouldnt be the wheel or a stiff chain link as you say it happens once per crank revolution).

Then use a cable tie on the frame as point of reference and check how concentric the chainring is running. You can always try undoing the bolts and re-seating it or rotating it on the spider.

Obviously also check the BB is in correctly and what kind of BB is it? If an external BB then make sure there is not too much pre-load.

Good shout andyl.
We loosened the back wheel and the stiffness disappeared. The chain must have been too tight at one point. All good now. Thanks.

Double post