Thwacking new freehub how should I approach

[brucelee]

I recently bought a new set of road wheels : shimano ultegra https://www.merlincycles.com/shimano-ul ... 92461.html. I've been riding XT hubs (760,780) for a little over a decade and had aksium wheels on my road bike all of which have small angles of engagement on the free hub. I can't recall ever having knackered a freehub, which given my gift for destroying other components is remarkable especially considering how many questions are posted by people having issues with them.
The new hubs have a much much larger angle between engagements and when spinning up I sometimes get a good loud thwack as the pawl engages causing the wheel to ring. Do I need to be wary of this ? Is it likely to be a cause of freehub failure and if so what's this best mindset for changing my spin up behaviour ?
Cheers,
Bruce.

[slowster]

I would take the wheel out of the frame and carefully count how many points of engagement there were. There should be at least 18 points of engagement on a Shimano road hub according to the link below, and according to SJS the corresponding model of stand-alone hub, FH-RS770, has 36 points of engagement, i.e. the same as the higher specification MTB freehubs such as XT.

https://bike.shimano.com/en-EU/technolo ... ement.html

https://www.sjscycles.co.uk/hubs-casset ... 2-x-142mm/

[the snail]

IME shimano freehubs should engage straight away, and there shouldn't be any significant noise. It sounds like the pawls are not engaging properly, and you need to get them freed up, or something will break sooner rather than later?

[brucelee]

Just measured them :
WH-RS770 (is printed on the hub) 18
T780 36 (with a double click on each click)
Aksium 40
They are strait pull hubs with low spoke count (20?) and look very different from the ones shown of SJS. The wheels are pretty new and have always been the same, there's no problem with them. The question is how to deal with the fact that the pawls get hit harder as a result of the additional momentum of the engagement hit. This sounds like a classic road bike problem.

[slowster]

Shimano's hubs have a good reputation, and 18 points of engagement is standard for their road hubs, which suggests that your hub should be OK.

The loud noise seems to be at the root of your concerns, and I wonder if it is the rest of the wheel that is making the freehub engagement sound noisy, i.e. acting as a form of soundbox and amplifying the noise.

[gregoryoftours]

I had this exact problem on a new wheel the other day. Alarmingly loud snapping 'clunk' intermittently when first applying power to the pedals. It was caused by too thick/much grease around the pawls and spring, which was sticking and not flicking the pawls out reliably. The awful snapping clank was the pawls settling properly into the ratchet under load.

The cure was to clean the grease off and apply thinner grease - in this case what I used was some designed for suspension forks.This was on a Nova freehub which has easy access to the pawls and spring, if yours is one of the Shimano models where the mechanism is hidden away inside the freehub body I'd be tempted to remove the freehub from the wheel, remove seals and flush from the back rather than fully dissemble a new freehub.

I'd say with a new Shimano wheel it's more likely to be that than bad manufacture or damage.

[brucelee]

The loud noise seems to be at the root of your concerns, and I wonder if it is the rest of the wheel that is making the freehub engagement sound noisy, i.e. acting as a form of soundbox and amplifying the noise.

This is what's happening, but I build all my wheels tight, and they all 'ring'. My concern here is that as a result of riding hubs with quick engagement for a long time, I might have developed a technique that is too heavy handed for road wheels. Guess I'll just have to be conscious of it and adapt.