Advice on building the rear GT500 hub into smaller rim

[Nicholas]

Hi All,

Apologies for my lazy question. I haven’t spent time researching building a wheel, but I am hoping there are some standards around hub to spoke and rim sizes.

I would like to fit a smaller rim to my GT500 using the original hub, figure its best to try and hold onto it for chain line compatibility and break pressure...

I'd like to go down to 16" or 17" if possible... The current is the stock 18" rim.

Has anyone done this before? Is it a straightforward process? Are there things I should consider? Is dressing the spokes important? I'd have a professional do the spokes for me...

Many thanks!
Nicholas

[H2RICK]

Please satisfy my curiosity as to why you'd want to go to a smaller rear wheel. If that's your bike in your avatar, I can't imagine changing the rear wheel on such a classic looking cafe bike.

[Nicholas]

Please satisfy my curiosity as to why you'd want to go to a smaller rear wheel. If that's your bike in your avatar, I can't imagine changing the rear wheel on such a classic looking cafe bike.

Oh, you will hate me for what I have done to it... I am almost finished with my build..I've done a complete rebuild and frame chop of the bike. I love the new look and the fiber glass tank and seat will be for sale...

I've decided to keep the wheel as a 18" for now and powder coated them in black and replaced the spoked with stainless steel.

[tz375]

This is really interesting. The bike was a period correct cafe racer style and even had the "right" color scheme. Now it has the standard DTT approach - tank sans paint, chopped frame with weld on loop, black rims. It is now a cookie cutter version of what some people think a Cafe Racer looks like. For the moment it still has all it's guts in place and no bare midriff with missing side covers and fenders, but is that on the menu too?

In other words it has changed from a Cafe Racer to a parody of itself.

I didn't mean that to read as harshly as it came out and it is your bike to do with as you see fit, but seriously Whiskey Tango Foxtrot?

Of course I have no idea if was as nice in reality as it looked in your avatar. Do you have any other pictures of it before the "build" by any chance? Are the new pipes from Titan?

[H2RICK]

Oh, you will hate me for what I have done to it...

Well, "hate" is a little strong considering I don't know you......but it's sad to see a classic cafe bike (which many, many people would sell their first born for) made over into......um....er.....something else (I'm being polite here ).

In other words it has changed from a Cafe Racer to a parody of itself.

+1

Sad, really......

[pearljam724]

As much as I like stock and dislike customization. I can see the need or desire to want to go smaller on the front. I very much, don't like 19 inch front rims. But, I can't see wanting to go smaller on the back other than the need for more room to customize the tail. I'll be following this thread, as I'm interested in hearing some of the replies of how and if it can be done with the stock hubs. Nicholas, were your previous gold rims on your bike those Thailand made sold on Ebay ? If so, what do you think of them ? Quality, fitment, looks, etc.

[Nicholas]

I’ll report my findings on the RIM.

In principal it is possible to build the rear wheel onto a smaller rim, but it would have required much thicker spokes and a specific dressing technique onto the hub. The hub is quite large in diameter, so there wouldn’t be a lot of play… but it would be possible.

The other issue is that if you want taller (or higher) tyres, you need to go wider on the RIM which then starts to create problems with clearance on your swing arm and possibly obstruct your chain line.

Based on these constraints, you would really need to have the bike assembled and with the wheel builder to find the right size of rim.

In the end I decided to stick with the stock Japanese rims that came with the bike as they fit and my battle axe tyres are much safer than the nicer looking firestone deluxe.

About the style:
well that is a matter of preference. One could argue that someone ruined a stock GT500 and turned it into a Café Racer…and it does seem the popular fashion on the custom circuit.
I bought the bike with the intention of keeping it as is…but found a number of mechanical issues so things started to come off…I then found myself inspired about motorcycles and wanted to learn as much as I could and decided that perhaps I could transform the bike into something that appeals to my style and perhaps my generation.

In the end I am proud of what I have been able to achieve, this is my first bike and I think the outcome will be so much better than where I started…it is quite easy to buy and off the shelf body kit…but a completely different experience fabricating rear fenders, retrofitting a gas tank onto a frame, rebuilding and engine taking care to find the right NOS engine parts. I studied exhausts and felt that the JEMCO pipes were the best and so I ordered them from Texas and had them nickel plated, I cannot wait to hear the sound!

It’s been a long journey and I cannot wait to ride my bike. Fingers crossed it is finished in 3 weeks, I am now battling the task of applying an anti-corrosive clear coat on my tank followed by a fuel resistant clear coat to keep it sealed….hope that POR15 Glisten PC lives up to the hype!

[tz375]

I like stock restored bikes, but my preference is to start with something incomplete and then turn it into something completely different. I have restored a few bikes and I always sell them off because I don't have much of a desire to ride one. Odd but true. I like things that are different.

You raised an interesting point that the current fashion is to cut and weld and "make it your own" and whatever the outcome, it's typically called a cafe racer. It's an odd development and the story is that cafe racers had to be built that way back in the day because the lads could not afford the good stuff, so they had to make it. There's more than a touch of historic revisionism in that.

Back in the day, none of us made or fabricated much of anything. There was no internet or books to tell us how and welders were not sold to the general public and besides, who could afford them. Fiberglass resin and mat were hard to get and most of us only had a basement or small unheated shed to work out of.

What we have in the UK was a great industry form which to choose parts. Crooks sold all sorts of race parts. So did Padgets. Read Titan, Bill Chuck, Dunstall, Dresda, Sondel, Wassell, Burton Bike Bits etc all had tanks and sets and fenders and lights and swept back pipes and rear sets and clip ons, so we paid to get printed catalogs and we bought all the parts we needed and did very little to the frames. The way we customized was to carefully (if we were lucky or had taste) the parts we wanted to buy and when we had saved enough we'd buy the next part.

Very few of us did much real modification. That was the exception rather than the norm back then. A full rebuild of a bike was rare as most of us used our bikes for transport. So to me, the whole Cafe Racer scene is a bit of a game of dress up and part of the fantasy is playing the role of the financially poor but talented lad. That's why almost every "build" thread includes pictures of the "builder" with an angle grinder making sparks playing at being a worker. It's part of the role play fantasy.

Back to your bike. We are working under what may be a huge misconception that the bike in your avatar is the one you are working on but that sounds like it's not the case.

Good call on keeping good tires on the bike. Those Firestone/Cocker tires are essentially a copy of what would be found on a Model T FORD and have no place on a motorcycle. They are not very safe and handle very poorly and that's matched with a lack of grip. They are vaguely reminiscent of an AVON Safety Mileage but they are not suitable for any bike that will be ridden.

Carry on.

[titan performance]

My 2 cents worth.....Nicholas, your cafe bike looked very nice indeed, and I would have been pretty pleased to have produced it. So to me it seems a little sad to have torn it down, when buying a tatty old shitter to start afresh with could have been an option. However, if it wasn't your style, and you didn't build it, then the choice was yours to do as you please....
I'm not into the bobber look at all, but shall watch your progress with interest none the less. It's always good to see other people's work come together.

[tz375]

So I'm confused. Is the picture in the avatar the starting point and if so was it much worse that it looks in that small picture or was it just not to your liking? We seem to be lacking a frame of reference for our comments and observations.

[Nicholas]

You’ll all have to wait until I am finished. I should have some pictures in three or so weeks.

The good news for most of you is that that the kit from my avatar will fit a stock GT500 and will be for sale in the following month. I have the pipes too...with some repair to the holes, they seem to be original allspeeds.

My new bike isn’t a bobber, I will be making a seat for it that will cover the whole rear end around the loop and the tank and most bits will be polished and clear coated...much nicer than fiberglass.

[tz375]

So that neat bike in the avatar is the starting point and you are changing that into a cookie cutter steam punk/post industrial satin steel art project. Each to their own.

So it goes from something unique to just another "Make it your own - follow the crowd" build. The other (more positive) way to look at it is that it is being transformed from a nice collection of parts from a past era into a modern interpretation of the genre. From and old vision of what a cafe racer was to a modern interpretation.

[Zunspec4]

Hi Nicholas,

To an extent, although very tasty, your original was not a lot different from many other takes on the Café Race (Triton like).

On the other hand (and far more intriguing), what's going on with that Boxer BMW in the background of your latest photo. Monoshock conversion? Do tell.

Cheers Zunspec

[Nicholas]

I am surprised how passionate people have been about voicing their disapproval of my work.

With the exception of the braced frame, the rest of the modifications were bolt-on. In my opinion, no drastic innovation and I could certainly repeat the look by fitting the parts onto another bike. If you want one, I’ll sell you the kit.

I don’t feel as though I should justify my actions, I have created a bike that I feel is beautiful and represents the characteristics of me, personalised for me, by me.

I don’t see the point in criticising someone’s work so passionately, it isn’t going to miraculously change things...so perhaps some thought into a desired outcome before posting would help? It is disappointing to see such close minded comments towards someone who appreciates vintage engineering and has re-purposed it for everyday use. Most people greedily acquire such bikes, store them to never be seen and then sell them off in “clearances”…right….

For the record, the bike was not fit for purpose. It had serious engine problems and as a whole was poorly assembled. The heads were finger tight, the pipes covered in filler and a splash of fuel on the casings washed off the paint. So I am sorry, the bike you are seeing in the avatar was merely built for show and not function. But truth be told, it would have eventually happened even if it was mechanically sound, this is my personality...

I bought this to become my primary bike, I love the engine and wanted to use it as the framework for my motorcycle. I have read other enthusiasts say they love old bikes, but wouldn’t ride them? I don’t get that...

I’m not upset by all of this and will still be posting my questions, hopefully you will still answer as some of you have provided good information.

But more importantly…in about three weeks I’ll be the happiest guy in London riding my own modern piece of history!

[Zunspec4]

Hi Nicholas,

In my usual incomplete use of English what I was saying was that the original format for your bike has been done hundreds of times before, nothing new. They great look when executed nicely (I like Café Racers) but at least your current intentions aim at a less used route. It's not like you a making a chopper out of the Lawrence of Arabia Brough .

What is that BMW all about, come on fess up.

Cheers Zunspec