I have a much loved titanium bike I use for day rides. I want to convert it to be an electric gravel bike ( it has big tyre clearance ). Like all road frames up until recently it has 130 mm rear drop outs. As I would prefer to use a rear hub motor this is a problem - they don't seem to exist ! I have done a limited amount of research and it seems that respacing a titanium frame is likely to be very difficult and I cannot find any reference to anyone who claims to have done it. So this is an appeal to the experts on this forum - is the 'magic motor' out there, or could one be tailored by deleting some spacers? I would want to retain an 8 speed cassette.
Motor for 130 mm rear drop outs
- Thread starter Babsbike
- Start date
Cassette motors are mainly wider than 135mm, but freewheel motors are rarely wider as long as you fit a 7-speed frewheel (or less). The 5mm between 130mm and 135mm is not noticeable when it comes to installing the motor. You won't have any problem installing or running with a 135mm wide motor.
My recommendation would be that you fit a 7 speed freewheel motor and change your shifter and derailleur to 7 speed. That adds about £25 to the cost of conversion if you buy new parts or about £10 for used ones.
The difference between 8-speed and 7-speed is insignificant when you have a motor.
You don't mention cost, but there are some more expensive cassette motors that would probably fit OK. Also, you don't give any idea about usage or performance characteristics required, so it's impossible to give you an exact recommendation.
My recommendation would be that you fit a 7 speed freewheel motor and change your shifter and derailleur to 7 speed. That adds about £25 to the cost of conversion if you buy new parts or about £10 for used ones.
The difference between 8-speed and 7-speed is insignificant when you have a motor.
You don't mention cost, but there are some more expensive cassette motors that would probably fit OK. Also, you don't give any idea about usage or performance characteristics required, so it's impossible to give you an exact recommendation.
Thanks for replies so far. I am going to simulate a 135 hub tomorrow and see how I get on. I am a bit sceptical it will be as easy as suggested because I had a similar issue last year fitting an XF08C ( 40mm nominal oln ) into a Cannondale that measured 137mm. I took out a washer to save 1mm and it just about worked but is a real pita to get in and out. The titanium chain stays seem pretty chunky so I am not optimistic but nothing ventured...as they say. I will report back.
You may be better off going with a crank drive bottom bracket motor like the TSDZ2. It's not heavy.
Well, today must be my lucky day ( makes up for this week's puncture ). I got an old MTB wheel, checked it was 135 and it was an easy fit with minimal stretch on the chain stays. My drop outs actually measure 131 but I was atonished how easy it was to fit compared with the battle I had ( and have) with my alu Cannondale. So the hunt is on - a 135 hub motor with 9 speed cassette. All suggestions welcome.
Thank you Woosh for your suggestion. A TSDZ2 from you was actually where I started from ( and I sent you a customer enquirey on this related to the bag battery option just before Xmas). However I have been so pleased with my XF08C that I thought that if a similar option existed in an appropriate size I would prefer to replicate this on my road/gravel bike. Just for fun (?) I might try and get my XF08C wheel in but I am pretty sure that is a stretch too far and could bring other alignment issues that I do not want.
Thank you Woosh for your suggestion. A TSDZ2 from you was actually where I started from ( and I sent you a customer enquirey on this related to the bag battery option just before Xmas). However I have been so pleased with my XF08C that I thought that if a similar option existed in an appropriate size I would prefer to replicate this on my road/gravel bike. Just for fun (?) I might try and get my XF08C wheel in but I am pretty sure that is a stretch too far and could bring other alignment issues that I do not want.
We have the new DWG2NC which is a rear motor with 135mm dropout but in 20in rim only at the moment. I will stock more sizes in late spring.
What do you mean? Both the XF08C and DWG2NC take standard 8,9,10 cassettes. 7 speed cassette needs a 2mm spacer.
Why would you want a 10 speed cassette on a lightweight e-bike. You will never need to use all of those ratios.
Conversion kits need to be compatible with a large range of cassettes.
for ready made bikes, I usually put 8 speed 11T-32T on my bikes with hub motors, 9-speed with crank motors. Bikes with 7-speed tend to have screw on freewheels. If you look closely, you can see that the rear sprockets on the freewheel wobble. This is sub optimal for the chain. Also, freewheels usually start with 13 teeth instead of 11 teeth for cassettes. Older cyclists would appreciate 11 teeth which lets them lower their cadence.
Well, I am definitely an older cyclist. Self powered Alpine ascents are but fading memories but I have recently rediscovered the pleasures of hilly terrain thanks to my Cannondale conversion. I really only use e power as hill assist, the rest of the time I ride 'powerless' and at relatively high cadence. I need all my gears , currently 3 x 9 on my road bike. I will probaley ditch the triple chainset when I get my road bike conversion but I will certainly keep 9 on the back! We all have different requirements.
My old boss from the 1940's would turn in his grave. I still remember when the first 5 speed rear only derailleur appeared in the shop.
"Ridiculous" he said, "who could ever want more than three gears?
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I remember well my first move from Sturmey Archer 3 speed to 5 speed, my father too questioned the need having been a fixed wheel commuter in his earlier years. 14 miles each way for an 8 hour day labouring in a brick yard and probably all on a cheese sandwich. The days of you did what you had to do and kept quiet about it.
Personally I run 3x8 on my bike and, living in hilly West Wales, I need 'em all. Especially with panniers full of shopping.
Personally I run 3x8 on my bike and, living in hilly West Wales, I need 'em all. Especially with panniers full of shopping.
True, but utility cycling in the 1940s and before was very different. Almost none of today's head down over drop handlebars inputting lots of effort at 20mph or more, plus cycling up steep hills.
Then it was upright, almost universally at around 10 mph and getting off and walking up hills of any steepness. Even we youngsters often walked up hills pushing our bikes.
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It may depend on how much motor power one uses? I nearly only ever use 3 out of my 8 gears because I hardly expend any effort, over mixed terrain, but I can well imagine people capable or desirous of getting exercise being more frugal in their use of motor assistance needing smaller changes of gear ratio and more of them.
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