Carrera Blast - chainset/bottom bracket resistance?

mattrixdesign2

Hi

Just been out on a wet and muddy 10mile ride with my lad, he recently got a Carrera Blast for his birthday...

http://www.halfords.com/webapp/wcs/stor ... yId_165602

I have just spent the last half hour cleaning the bikes, when I was working on his chain I noticed when turning the pedals backwards there was a lot of resistance (it wasn't smooth and easy), I thought this was odd, so I dropped the chain off the chainset, tried it again, and it was still stiff, a quick spin, let go and it stops!

This can not be right - any ideas what it could be (overly tight BB?).

It is about to go back to Halfords for its 6wk check up, and I will insist it is put right, but I would like to know what the problem could be.

supersonic

I can't see what type of bottom bracket is has - may be an old cup and cone type, in which case it probably needs readjusting.

heez29

supersonic wrote:

I can't see what type of bottom bracket is has - may be an old cup and cone type, in which case it probably needs readjusting.

It is but you'll need a BB tool to do so. Sometimes the driveside can be a pain (even on new bikes) so dont be afraid to give it some elbow grease.

Chunkers1980

So is it old Cup and cone?

Is the Axel bent?

If it's only cup and cone you can sometimes get away with a hammer and screw driver to undo the lock ring and undo the whole thing a bit.

First I'd check it's not bent tho.

mattrixdesign2

Not sure what the BB type was, some sort of plastic (grey) sealed unit. The chap at Halfords (Leigh) was very helpful, and sorted it, no hassles. Even the new one is slightly slow to turn when spinning it, but I think it may just need some bedding in?

diy

Opening up an old thread, but my kid has the same bike and his has jammed solid. Any guides to these cup and cone systems?

The Rookie

Read the last post, his wasn't cup and cone but a sealed item, remove old one, buy new one to same dimensions (written on it) and fit.

poah

the BB on my son's carrera blast is a mix of a sealed and cone BB very odd unit. it was never that smooth and there was a major difference when I fitted an UN55.

diy

did you have to replace the crankset when you swapped for the UN55?

The Rookie

No, he won't, just get the same width axle.

poah

diy wrote:

did you have to replace the crankset when you swapped for the UN55?

yes but that was the reason for the new BB, I needed a thinner axle size to fit the low profile crank. you can just swap it out for the same sized axle though ~ 68 X 122.5mm I think

diy

thanks unfortunately I don't have any 7 speed cranksets kicking around.

The Rookie

A 5,6,8 are the same and a 9 will work fine.

diy

thanks, in which case I have an 8 speed and 9 speed I can try.

poah

I wrote a small article about kids cranks which you might find useful. I changed the crank on Lewis's blast because it was way too long for his leg length. http://wp.me/p4HYH0-v

diy

Thanks in the end I had an old square taper BB kicking around. It had a shorter shaft, but was within the limits and just meant reindexing the gears. Surprised how utter poo the original components were. The SRAM parts are just the headline parts. But then the bike costs about the same as a decent crankset and pedals, so can't complain too much.