Powder coating DaHon aluminium frames?

[HenryC]

Hi guys, this is my first post here. I'm new ish to folding bikes, but used to commute on a Raleigh 20 Stowaway (which was very fun, but very heavy). I've just got an old DaHon Vybe off eBay and I've stripped it down completely for rebuilding/ modifying.

I'm just curious if anyone has sand/shot blasted down and powder coated any DaHon 'Dalloy' aluminium frame before? If so, did it go well?


The current paint job is in pretty poor condition. I've got a quote from a car alloy repairer near me for £50 for shot blasting and powder coating. They've told me the powder is baked on at 180C for 20 minutes. I'm a bit worried about affecting the strength of the frame by heat treating it.

I've tried to read all I can about the risk of heat treatment on aluminium bike frames, but it seems like it really depends on the tempering of the specific grade. From what I can tell, the Dalloy grade sounds like it is tempered to increase hardness, and I've read that tempering (artificial ageing) of some grades can be at temperatures as low as 100C. I tried sending an email to DaHon, but I doubt I'll get a response (not least because it's their IP).

Since it's a budget bike, I'd rather not pay hundreds for a proper paint job. The powder coating is tempting because of how durable it would be too.

Plan B would be to just ask them to do the shot blasting, then paint the thing myself with a rattle can I guess.

Has anyone been down a similar road to this?

Thanks, Henry

 

[Fastpedaller]

Rattle can........ It would depend if you can make the paint stick long-term. I'd suggest you'd need an etch primer for a start, but I'm no expert.

 

[MichaelW2]

Do you paint the locking surfaces ? On my Dahon they are unpainted.

 

[u_i]

You need to get special paint for alu. My experience stems from 2 projects, a box for an electric circuit on a bike and a chain guard I made out of alu. In the first case, it was a paint in a can, declared to be for alu, and it held poorly. In the second case, it was a 2-component system, a paste that you treated the surface with and then removed it fully + the coating itself. The latter held reasonably well.

 

[midlife]

This mob think its OK.....

https://ctc-powder-coating.co.uk/our-work/bicycles/

 

[Drago]

Not likely to be an issue. I think Dahon use 7005, which if I recall is heat treated at two different temps for something like 10,p or 12 hours rather than aged like 6061 and the temps used in powder coating won't affect it.

 

[bonzobanana]

Dalloy is a marketing term nothing more, it's not a special aluminium in anyway. Dahon buy their bikes mostly from other factories and such factories may use 6061 or 7005 or maybe even other aluminium alloys. The Dahon dual suspension 20" folding bike (I forget the name) is a fuji-ta bike which I think they have exclusive rights to sell outside Asia although I think I've seen the same frame on a ebike with a different brand. In Asia it would be mainly sold under the 'Battle' brand. The Dahon bikes sold in Europe used to be assembled in Bulgaria by Max.com from parts from various Asian factories. It was the same situation with Trek I think who give their aluminium fake names like Alpha etc. There was one bike that was made by various Asian factories so some were 7005 and others were 6061 but both were described using Trek's fake alloy name despite being different aluminiums. There are true special aluminium alloys but there are also many fake aluminium alloys just for marketing purposes. It's perfectly legal to call aluminium whatever you like 'JimBowen180 Xtra light' etc.

 

[Fastpedaller]

This mob think its OK.....

https://ctc-powder-coating.co.uk/our-work/bicycles/

But they call them Pushbikes! not pedal cycles Grr

 

[HenryC]

Thanks so much for the replies guys, I knew I'd find some knowledgeable people here!

Good to know about pitfalls of the rattle can approach. Feels like more trouble than just living with an old paint job.

Yes - the locking surfaces (the faces which sit against eachother) are painted on mine, along with the outside surfaces of the hinges. I guess I'll have to make sure the extra mm from thick powder coating doesn't affect the folding.

And really great to know about Dalloy! I have completely fallen for the marketing. I assumed it was some secret recipe

Given these answers, and since it's a cheap frame, I think I'll risk the powder coat and report back here on results. I might give that CTC outfit a quick call too to check prices and see what they recommend.

 

[Drago]

'JimBowen180 Xtra light' etc.

Is it any good?


They'll mask the bits you don't want coated if you ask nicely.