[gexas]

I believe since this is probably a technical question I'd try and post it here. I have an '06 GT Avalanche that has a Shimano M475mm hub. Whenever it gets below 32 degrees the hub doesn't engage so I can peddle. This happens after I back peddle or just coast on the bike. I have a feeling that moisture is in the hub and once the pawls or whatever they are are in their disengaged position when I'm coasting or backpeddling then they freeze there. I have never taken the hub apart to investigate because I don't have the tools for it.

Does anyone agree with this and if so how can I fix it? I have other friends that have other hubs which don't do this even when they have ridden through the same creeks, rain,etc. that I have.

All help is appreciated.

Eric

 

[jonKranked]

Might not be moisture, might be the grease. As the temperature drops the viscosity in some greases will increase, resulting in increased friction. The higher velocity will slow the pawls down from engaging immediately, resulting in skipping engagements. Try a teflon based grease, or something thin. I've had really good luck with Phil Wood grease (although its not teflon based). Should run you about $12 at your LBS.

edit: Or, if it hasn't been serviced recently, it might just be dirty and need to be cleaned and regreased. Try that first.

 

[gexas]

hmmm, didn't think about the grease thickening up but that is a great point. I will give it a try. Do you know if those hubs are decent or should be replaced? That is, in the event it isn't the grease and it is moisture or just a sub standard hub. These are the second set up hubs that I've had since I bought the bike brand new this year in March. GT replaced the first hub as the bearings were shot after a short amount of riding.

Thanks for any info.,

E

 

[sanjuro]

Most Shimano hubs are crap. The advantage is that the freehubs are easy to replace and not too expensive.

I use a few Shimano hubs, and they work ok. I also have a DT and Chris King, which costs $300+, and the quality is much higher.

 

[gexas]

When you say "freehub" what does that mean?

Thanks,
E

 

[sanjuro]

The old school method of "freewheeling", when the cogs engage when you pedal and spin freely when you aren't, was the freewheel. The pawls and springs was internal to the freewheel.

One major problem with freewheels compared with modern systems is that since you screwed the whole mechanism onto the hub and it tightened when you pedaled, it could be difficult to remove. Also freewheels are heavier than what we use today, freehubs.

The freehub system is the freewheeling mechanism is attached to the hub, and then splined cogs are mounted on the freehub with a lockring. The cogs are easy to remove since they are not torqued on, and the Shimano freehub is not particularly hard to replace either.

Chris King and DT have also moved away from the classic pawl/spring combination, resulting in an even lighter and more reliable system. Other companies like Industry 9 use higher quality parts and better designs than Shimano.

 

[johnbryanpeters]

I have ridden a lot with temperature in the teens and twenties and while the freehub gets a little sluggish, it does not fail to engage.

I suspect that your idea about moisture may be correct.

The best approach is probably to get a bike shop to clean and lubricate the hub.

You could try heating it with a heat lamp to drive the moisture out, but you might also melt the grease and/or the seals...

Take it to a shop and don't let them sell you a tony hub. Shimano parts are reasonably priced and generally available.